LDraw.org Wiki - User contributions [en]

LDMakeList

2014-07-26T04:17:17Z

Timgould: /* Mac */

{{Software
|developer=Tim Gould
|function=Library utility
|version=2.01
|platform=Windows
|website=[http://code.google.com/p/ldmakelist/ LDMakeList]
}}
'''LDMakeList''' is a tool created by [[Meet Tim Gould|Tim Gould]] as a replacement for the default '''mklist.exe''' that is included with LDraw.

LDMakeList has a number of advantages over mklist.exe, including:
* The ability to disregard parts whose names begin with certain characters, by using the -h command, meaning that colour aliases and other parts that are defined with leading character such as _ or ~ are not listed.
* Different sorting options (eg. -d for description, -n for filename, -p to leave patterns at the end)
* The ability to shorten long descriptions to ensure compatibility with older LDraw software

==Mac==
Instructions for Mac (NB. you probably require Maverick to run this)

# Save <code>LDMakeList-2.14-Mac.tar</code> ([https://drive.google.com/folderview?id=0B1sfkk_j3usWdEYzNkNaNW5PbjA&usp=sharing|from here]) without changing its filename into your LDraw directory
# Double click on it in <code>Finder</code>, then go into the directory it creates
# Double click on <code>RunLDMakeList</code>, it will run with -d in the parent directory
# If you extract to anywhere else, first copy <code>LDMakeList</code> and <code>RunLDMakeList</code> into your LDraw directory, and then run[1]

'''NB''' Mac power users may also use <code>Terminal.app</code>, then cd into the LDraw directory, then run <code>LDMakeList</code> with any of the command line arguments listed below.

[1] This strips <code>LDMakeList-Mac</code> off the end of the script's directory
if present, and runs there. If not present, it simply runs in the
script's directory.

==Usage==
By running the executable file, the following information is supplied:

<pre style="overflow:auto;">LDMakeList
Use -? for help, -v for version
Valid options are:
-d or -D : sort by _D_escription (default)
-n or -N : sort by file_N_ame
-p or -P : sort by description (_P_atterns at end of file)
-s or -S : use _S_hort descriptions*
-m or -M : include pri_M_itives in the list
-u or -U : include _U_nofficial part directory
-a or -A : exclude _A_liases from the list
-r or -R : _R_emove duplicate entries (experimental)
-o or -O : Include _o_fficial parts only
-l[DIRNAME] or -L[DIRNAME] : Read from _L_Draw director DIRNAME
-h[C] or -H[C] : -H_ide descriptions starting with character(s) [C]
-i[C] or -I[C] : str_I_p leading character(s) [C] from descriptions
-x or -X : do not write parts._x_ml file

eg. "LDMakeList -d -h=_ -i~" will generate a parts.lst file sorted
by description (-d), excluding colour = and some parts _ (-h=_),
and removing the ~ character (-i~) from the start of descriptions

The -L tag lets you select the base directory for your LDraw
installation (defaults to environment variable LDRAWDIR)
eg. "LDMakeList -d -L." sorts by descriptions in the present
directory

eg. "LDMakeList -u" will look in [LDRAWDIR]/Unofficial/Parts
as well as [LDRAWDIR]/Parts for part files

The -m tag is not recommended for beginner LDraw users

* The old limit for part descriptions is 64 characters and it is
possible that descriptions longer than this might break some
old software. This ensures that the output filenames are no
longer than 64 characters. Use if programs are giving errors.

Sort by [D]escription or [N]umber?</pre>

Selecting either D or N will arrange the data in the outputted parts.lst file in a certain order. The option to select D or N will not appear if the option -d or -n or -p is selected.

By running the application from the command line, the other switches can also be enabled or disabled.

==External links==
*[http://code.google.com/p/ldmakelist/ LDMakeList] on Google Code Project Hosting

[[Category:Software]]

LDMakeList

2014-07-25T23:44:06Z

Timgould:

{{Software
|developer=Tim Gould
|function=Library utility
|version=2.01
|platform=Windows
|website=[http://code.google.com/p/ldmakelist/ LDMakeList]
}}
'''LDMakeList''' is a tool created by [[Meet Tim Gould|Tim Gould]] as a replacement for the default '''mklist.exe''' that is included with LDraw.

LDMakeList has a number of advantages over mklist.exe, including:
* The ability to disregard parts whose names begin with certain characters, by using the -h command, meaning that colour aliases and other parts that are defined with leading character such as _ or ~ are not listed.
* Different sorting options (eg. -d for description, -n for filename, -p to leave patterns at the end)
* The ability to shorten long descriptions to ensure compatibility with older LDraw software

==Mac==
Instructions for Mac (NB. you probably require Maverick to run this)

# Save <code>LDMakeList-2.14-Mac.tar</code> ([https://drive.google.com/folderview?id=0B1sfkk_j3usWdEYzNkNaNW5PbjA&usp=sharing|from here]) without changing its filename into your LDraw directory
# Double click on it in <code>Finder</code>, then go into the directory it creates
# Double click on <code>RunLDMakeList</code>, it will run with -d in the parent directory
# If you extract to anywhere else, first copy <code>LDMakeList</code> and <code>RunLDMakeList</code> into your LDraw directory, and then run[1]

[1] This strips <code>LDMakeList-Mac</code> off the end of the script's directory
if present, and runs there. If not present, it simply runs in the
script's directory.

==Usage==
By running the executable file, the following information is supplied:

<pre style="overflow:auto;">LDMakeList
Use -? for help, -v for version
Valid options are:
-d or -D : sort by _D_escription (default)
-n or -N : sort by file_N_ame
-p or -P : sort by description (_P_atterns at end of file)
-s or -S : use _S_hort descriptions*
-m or -M : include pri_M_itives in the list
-u or -U : include _U_nofficial part directory
-a or -A : exclude _A_liases from the list
-r or -R : _R_emove duplicate entries (experimental)
-o or -O : Include _o_fficial parts only
-l[DIRNAME] or -L[DIRNAME] : Read from _L_Draw director DIRNAME
-h[C] or -H[C] : -H_ide descriptions starting with character(s) [C]
-i[C] or -I[C] : str_I_p leading character(s) [C] from descriptions
-x or -X : do not write parts._x_ml file

eg. "LDMakeList -d -h=_ -i~" will generate a parts.lst file sorted
by description (-d), excluding colour = and some parts _ (-h=_),
and removing the ~ character (-i~) from the start of descriptions

The -L tag lets you select the base directory for your LDraw
installation (defaults to environment variable LDRAWDIR)
eg. "LDMakeList -d -L." sorts by descriptions in the present
directory

eg. "LDMakeList -u" will look in [LDRAWDIR]/Unofficial/Parts
as well as [LDRAWDIR]/Parts for part files

The -m tag is not recommended for beginner LDraw users

* The old limit for part descriptions is 64 characters and it is
possible that descriptions longer than this might break some
old software. This ensures that the output filenames are no
longer than 64 characters. Use if programs are giving errors.

Sort by [D]escription or [N]umber?</pre>

Selecting either D or N will arrange the data in the outputted parts.lst file in a certain order. The option to select D or N will not appear if the option -d or -n or -p is selected.

By running the application from the command line, the other switches can also be enabled or disabled.

==External links==
*[http://code.google.com/p/ldmakelist/ LDMakeList] on Google Code Project Hosting

[[Category:Software]]

LDMakeList

2013-10-06T10:31:07Z

Timgould:

{{Software
|developer=Tim Gould
|function=Library utility
|version=2.01
|platform=Windows
|website=[http://code.google.com/p/ldmakelist/ LDMakeList]
}}
'''LDMakeList''' is a tool created by [[Meet Tim Gould|Tim Gould]] as a replacement for the default '''mklist.exe''' that is included with LDraw.

LDMakeList has a number of advantages over mklist.exe, including:
* The ability to disregard parts whose names begin with certain characters, by using the -h command, meaning that colour aliases and other parts that are defined with leading character such as _ or ~ are not listed.
* Different sorting options (eg. -d for description, -n for filename, -p to leave patterns at the end)
* The ability to shorten long descriptions to ensure compatibility with older LDraw software

==Usage==
By running the executable file, the following information is supplied:

<pre style="overflow:auto;">LDMakeList
Use -? for help, -v for version
Valid options are:
-d or -D : sort by _D_escription (default)
-n or -N : sort by file_N_ame
-p or -P : sort by description (_P_atterns at end of file)
-s or -S : use _S_hort descriptions*
-m or -M : include pri_M_itives in the list
-u or -U : include _U_nofficial part directory
-a or -A : exclude _A_liases from the list
-r or -R : _R_emove duplicate entries (experimental)
-o or -O : Include _o_fficial parts only
-l[DIRNAME] or -L[DIRNAME] : Read from _L_Draw director DIRNAME
-h[C] or -H[C] : -H_ide descriptions starting with character(s) [C]
-i[C] or -I[C] : str_I_p leading character(s) [C] from descriptions
-x or -X : do not write parts._x_ml file

eg. "LDMakeList -d -h=_ -i~" will generate a parts.lst file sorted
by description (-d), excluding colour = and some parts _ (-h=_),
and removing the ~ character (-i~) from the start of descriptions

The -L tag lets you select the base directory for your LDraw
installation (defaults to environment variable LDRAWDIR)
eg. "LDMakeList -d -L." sorts by descriptions in the present
directory

eg. "LDMakeList -u" will look in [LDRAWDIR]/Unofficial/Parts
as well as [LDRAWDIR]/Parts for part files

The -m tag is not recommended for beginner LDraw users

* The old limit for part descriptions is 64 characters and it is
possible that descriptions longer than this might break some
old software. This ensures that the output filenames are no
longer than 64 characters. Use if programs are giving errors.

Sort by [D]escription or [N]umber?</pre>

Selecting either D or N will arrange the data in the outputted parts.lst file in a certain order. The option to select D or N will not appear if the option -d or -n or -p is selected.

By running the application from the command line, the other switches can also be enabled or disabled.

==External links==
*[http://code.google.com/p/ldmakelist/ LDMakeList] on Google Code Project Hosting

[[Category:Software]]

LDMakeList

2013-05-15T06:53:11Z

Timgould:

Meet Michael Heidemann

2013-02-13T21:47:54Z

Timgould:

Michael is currently a member of the LDraw Steering Committee (SteerCo) and author of DatHeader.
{{PersonPic|Name=Michael "Mike" Heidemann|Username=mikeheide|Age=49|Country=Germany|Roles=Software author|ImageSource=}}

'''Name:''' Michael "Mike" Heidemann (Username: mikeheide)

'''Age:''' 49 (in 2012)

'''Gender:''' Male

'''Location:''' Bielefeld, Germany, Europe

'''History with LDraw:''' Michael found LDraw while he was searching for building instructions for a set his wife had bought for his son. Since he already had a little experience with POV-Ray his interest in makeing some old sets in LDraw was piqued. Soon he discovered that there were some/many pieces missing from the LDraw parts library and he started making them himself.

'''Related interests:''' He is also a passionate collector. His first complete range of LEGO sets was the ZNAP theme. Using his experience in computer programming with visual basic he also wrote some programmes which deal with LDraw files.

'''Unrelated interests:''' Michael is a sales manager by education and became a computer programmer by interest. He also likes sports - especially badminton.

Meet Michael Heidemann

2013-02-13T21:44:39Z

Timgould: Created page with "Michael is currently a member of the LDraw Steering Committee (SteerCo) and author of DatHeader. '''Name:''' Image:michaelheidemann.jpg Michael "Mike" Heidemann (Use..."

Michael is currently a member of the LDraw Steering Committee (SteerCo) and author of DatHeader.

'''Name:''' [[Image:michaelheidemann.jpg]] Michael "Mike" Heidemann (Username: mikeheide)

'''Age:''' 45 (as of 2008)

'''Gender:''' Male

'''Location:''' Bielefeld, Germany, Europe

'''History with LDraw:''' Michael found LDraw while he was searching for building instructions for a set his wife had bought for his son. Since he already had a little experience with POV-Ray his interest in makeing some old sets in LDraw was piqued. Soon he discovered that there were some/many pieces missing from the LDraw parts library and he started making them himself.

'''Related interests:''' He is also a passionate collector. His first complete range of LEGO sets was the ZNAP theme. Using his experience in computer programming with visual basic he also wrote some programmes which deal with LDraw files.

'''Unrelated interests:''' Michael is a sales manager by education and became a computer programmer by interest. He also likes sports - especially badminton.

Meet Travis Cobbs

2012-12-06T22:42:18Z

Timgould:

Travis is currently a member of the LDraw Standards Committee (LSC), and the author of [http://ldview.sourceforge.net/ LDView].

{{PersonPic|Name=Travis Cobbs|Username=tcobbs|Age=38|Country=USA|Roles=LSC,JJMA Recipient|ImageSource=File:TravisCobbs.jpg}}

'''Name:''' Travis Cobbs (Username: tcobbs)

'''Age:''' 38 (as of 2011)

'''Location:''' San Diego, CA, USA

'''History with LDraw:'''
Travis started using LDraw in 2000, and immediately decided that a real-time 3D viewer for LDraw models would be very useful. On 03 June, he released L3DView 0.1, a very rudimentary proof-of-concept. This was shortly renamed LDView to avoid confusion with Lars C. Hassing's programs with an L3 prefix (L3Lab and L3P). On 17 Oct, 2000, he release LDView 1.0, and has been releasing new versions ever since. Travis was elected to the LDraw Standards Committed starting in 2006 and has been reelected in each term up through 2011.

'''Related interests:'''
Travis's LEGO dark age ended in 1996, and he's been an AFOL ever since. Even though his career is as a software engineer, he still enjoys computer programming as a hobby. He saw LDView as a way to merge this hobby with his LEGO hobby.

[[Category:People]]

Meet Steffen Lohse

2012-12-06T22:31:57Z

Timgould:

{{PersonBox|Name=Steffen Lohse|Username=Steffen|Age=38|Country=Germany|Roles=JJMA Recipient,Parts Author|ImageSource=}}

'''Name:''' Steffen Lohse (Username: Steffen)

'''Age:''' 38 (as of 2012)

'''Gender:''' Male

'''Location:''' Hamburg, Germany, Europe

'''History with LDraw:'''

I had discovered LDRAW around late 2002 and immediately fell addicted to it for the simplicity and elegance of its principle.
It allowed me to revive long lost child memories of LEGO, and I immediately started re-building many of my favourite sets.
At that time, I was using [[L3Lab]] and [[MLCad]] to create 3D scenes, which I then converted to [[POVRay]] format using [[L3P]].
I quickly discovered that still many parts were missing and found fun in creating them, thus quickly became a parts author.
As a child I had loved the [http://peeron.com/inv/sets/7740-1 12V Trains] and thus found it necessary to create the
track parts for that system, which were missing at that time:

[[Image:12V Slotted.jpg|640px]]

The most complicated part of that set was the the train point part <code>73696c04.dat</code>,
which still needs improvement. At the time of creating it, [http://philohome.com/ldraw.htm Philo's fabulous LDRAW authoring tools]
didn't exist yet. I also carefully checked that the newly created 12V train track parts were properly integrated into [[BlueBrick]],
so you now can elegantly create a train track layout using that software, and then export to <code>.ldr</code> format,
then do a [[POVRay]] render.

[[Image:Collection of 12V Train Parts.jpg|640px]]

In the meantime, I've created some 400+ parts now.
My favourite LEGO themes are the 12V trains, Fabuland, Classic Legoland City and Technic.
Nowadays, I am just using [[LDView]] to export my LDRAW scenes to [[POVRay]] format, adding just some custom lighting setup.

'''Related interests:'''

I work as a software developer in the automotive industry, play the piano and am
addicted to Lindy Hop, so we can meet at [http://www.herrang.com Herräng Dance Camp] in Sweden.

'''Contact:'''

My mail address for LDRAW purposes is <code>muchelchupser(AT)web.de</code>.
(It is a word play of a German term for people living in Hamburg.)

[[Category:People]]

Category:HowTo

2012-11-13T20:24:53Z

Timgould: Created page with "Various How To guides"

Various How To guides

Fix Winding in DATHeader

2012-11-13T20:22:45Z

Timgould: Created page with "=How to fix a portion of wrong winding in a file with DATHeader= If you have for example a file where at some point the winding is changed: <pre> 0 BFC CW 1 16 5.899 86 -55.1..."

=How to fix a portion of wrong winding in a file with DATHeader=

If you have for example a file where at some point the winding is changed:
<pre>
0 BFC CW
1 16 5.899 86 -55.174 1.029 -0.751882 0 0 0 2 1.1735 1 0 rect2p.dat
5 24 4.8702 88 -56.347 4.8702 84 -56.347 6.9282 88 -54 2.0705 88 -57.7273
5 24 6.9282 88 -54 6.9282 84 -54 4.8702 88 -56.347 10.9282 88 -47.0718
4 16 -4 88 -56.9282 -2.0706 88 -57.7274 -2.0521 88 -55.6382 -3 88 -55.1962
4 16 2.0706 88 -57.7274 4.8702 88 -56.347 3.6526 88 -54.7603 2.0521 88 -55.6382
4 16 4.8702 88 -56.347 6.9282 88 -54 5.1961 88 -53 3.6526 88 -54.7603
0 BFC CCW
</pre>
Go to the Editor Tab. Mark the lines between both BFC statements. Click the right mouse button and choose from the context menu „Reverse Winding“.

You will got the following code:
<pre>
0 BFC CW
1 16 5.899 86 -55.174 1.029 -0.751882 0 0 0 2 1.1735 1 0 rect2p.dat
5 24 4.8702 88 -56.347 4.8702 84 -56.347 6.9282 88 -54 2.0705 88 -57.7273
5 24 6.9282 88 -54 6.9282 84 -54 4.8702 88 -56.347 10.9282 88 -47.0718
4 16 -3 88 -55.1962 -2.0521 88 -55.6382 -2.0706 88 -57.7274 -4 88 -56.9282
4 16 2.0521 88 -55.6382 3.6526 88 -54.7603 4.8702 88 -56.347 2.0706 88 -57.7274
4 16 3.6526 88 -54.7603 5.1961 88 -53 6.9282 88 -54 4.8702 88 -56.347
0 BFC CCW
</pre>
Now delete both BFC statement lines.
<pre>
1 16 5.899 86 -55.174 1.029 -0.751882 0 0 0 2 1.1735 1 0 rect2p.dat
5 24 4.8702 88 -56.347 4.8702 84 -56.347 6.9282 88 -54 2.0705 88 -57.7273
5 24 6.9282 88 -54 6.9282 84 -54 4.8702 88 -56.347 10.9282 88 -47.0718
4 16 -3 88 -55.1962 -2.0521 88 -55.6382 -2.0706 88 -57.7274 -4 88 -56.9282
4 16 2.0521 88 -55.6382 3.6526 88 -54.7603 4.8702 88 -56.347 2.0706 88 -57.7274
4 16 3.6526 88 -54.7603 5.1961 88 -53 6.9282 88 -54 4.8702 88 -56.347
</pre>
Now hit the "commit code changes" button. You can now save the file.

Finished.

[[Category:HowTo]]

Software Downloads

2012-08-21T23:39:13Z

Timgould:

Here you can find various software for download. It is an interim solution to the old download page until we can bring it back to life.

=LDraw Viewers=
{{SoftwareDownload|Name=LDView|Size=<2Mb|URL=http://ldview.sourceforge.net/|Description=The most popular LDraw viewer for Windows (also available for Mac and Linux). Very versatile and customisable}}

=LDraw Editors=
{{SoftwareDownload|Name=MLCAD|Size=<2Mb|URL=http://mlcad.lm-software.com/|Description=Most popular editor for Windows.}}

=Miscellaneous Software=

[[Category:Software]]

Template:SoftwareDownload

2012-08-21T23:37:42Z

Timgould:

{| style="text-align: left; width: 60%; background: #C3D7FA; border: solid 1px;"
|-
|'''Name''': || {{{Name}}} ||'''Size''': || {{{Size}}}
|-
||'''Link''': ||colspan="3"| [{{{URL}}} {{{URL}}}]
|-
|colspan="4"| {{{Description}}}
|}

Software Downloads

2012-08-21T23:36:31Z

Timgould:

Template:SoftwareDownload

2012-08-21T23:34:25Z

Timgould:

{| style="text-align: left; width: 100%; background: #C3D7FA; border: solid 1px;"
|-
|'''Name''': || {{{Name}}} ||'''Size''': || {{{Size}}}
|-
||'''Link''': ||colspan="3"| [{{{URL}}} {{{URL}}}]
|-
|colspan="4"| {{{Description}}}
|}

Software Downloads

2012-08-21T23:34:02Z

Timgould:

Here you can find various software for download. It is an interim solution to the old download page until we can bring it back to life.

=LDraw Viewers=
{{SoftwareDownload|Name=LDView|Size=~2Mb|URL=http://ldview.sourceforge.net/|Description=The most popular LDraw viewer for Windows (also available for Mac and Linux). Very versatile and customisable}}

=LDraw Editors=

=Miscellaneous Software=

[[Category:Software]]

Template:SoftwareDownload

2012-08-21T23:31:41Z

Timgould:

Template:SoftwareDownload

2012-08-21T23:31:07Z

Timgould:

{| style="text-align: left; width: 100%; background: #C3D7FA; border: solid 1px;"
|-
|'''Name''': || {{{Name}}} ||'''Size''': || {{{Size}}}
|-
||'''Link''': |colspan="3"| [{{{URL}}} URL]
|-
|colspan="4"| {{{Description}}}
|}

Template:SoftwareDownload

2012-08-21T23:30:04Z

Timgould: Created page with "{| style="text-align: left; width: 100%; background: #C3D7FA; border: solid 1px;" |- |'''Name''': || {{{Name}}} ||'''Size''': || {{{Size}}} |- |colspan="3" align="center"|'''L..."

{| style="text-align: left; width: 100%; background: #C3D7FA; border: solid 1px;"
|-
|'''Name''': || {{{Name}}} ||'''Size''': || {{{Size}}}
|-
|colspan="3" align="center"|'''Link''': || [{{{URL}}} URL]
|-
|colspan="3" align="center"| [[{{{ImageSource}}}|frameless]]
|}

Software Downloads

2012-08-21T23:27:08Z

Timgould: Created page with "Here you can find various software for download. It is an interim solution to the old download page until we can bring it back to life. =LDraw Viewers= =LDraw Editors= =Mis..."

Here you can find various software for download. It is an interim solution to the old download page until we can bring it back to life.

=LDraw Viewers=

=LDraw Editors=

=Miscellaneous Software=

[[Category:Software]]

T-Junction

2012-08-10T01:18:02Z

Timgould:

T-Junctions in LDraw parts can often lead to unavoidable rendering artifacts, so it's best to avoid them when possible.

By Travis Cobbs.

==Definition==

A T-junction is a spot where two polygons meet along the edge of another polygon, like so: [[Image:T_Junction1.png]] If these occur in a random location along a diagonal edge, it's often the case that the precise coordinates of the junction cannot be put into the DAT file. Many people would agree that that would be bad. However, when they occur at precise coordinates, it's tempting to say that there's nothing wrong with them, since there shouldn't be any round-off problems. Unfortunately, when you go to arbitrary 3D views, this turns out not to be the case.

It turns out that a 3D rendering engine can only guarantee that a closed polygon mesh is tight (no visible gaps) if the mesh does not contain any T-junctions. The reason for this is that once you start rotating things in 3D, the precise coordinates stop being precise.

The following illustrates this problem:

[[Image:T_Junction2.png]]

Notice the white dots. If you view the file in wireframe, you'll see that these dots occur along the seams between polygons. Please note that the actual coordinates of all the points in the file are fine (as far as I know; I haven't checked, but I believe Mike). The dots are there because from that point of view, the edges are diagonal, and diagonal edges require rounding. Essentially, the rounding cannot be guaranteed to be the same on the polygons along the edge if those polygons don't share common end-points on both ends.

This may be difficult to understand. Hopefully the following will illustrate the point:

[[Image:T_Junction3.png]] [[Image:T_Junction3a.png]]These images were done in Microsoft Paint (then blown up by 800%), with two sets of lines that are designed to be right next to each other. The image on the left represents the T-Junction case. The one on the right represents the case without a T-junction. As you can see, there are gaps in the image on the left. This isn't quite the same as T-junctions in a part file, since the above sets of lines were drawn with 1 pixel difference. However, since 3D renderers are representing adjoining polygons with an infinitely thin edge between them, it actually works out to a very similar problem. (Note that the red line in the left image was actually drawn starting at the bottom-most green pixel, and the green line was then drawn with the same end-point.)

==Getting rid of T-junctions your LDraw part==

As far as I know, a T-junction in a triangle or quad can always be removed by the addition of one triangle. This can be tedious, but I don't know of any automated solution. Also, there are often better ways to get rid of T-junctions than adding a triangle. For example:

[[Image:T_Junction4.png]] [[Image:T_Junction5.png]] [[Image:T_Junction6.png]]

Notice that the bottom version is made up of 4 quads, while the middle version has 3 quads and 2 triangles. That makes the bottom version better, sort of. Most renderers will at some point divide all the quads into triangles, and both versions result in the same number of final triangles, so it's not necessarily as much better as it might look. (I mention this, because things get a whole lot more complicated as the shapes become more complex, and it's really not worth trying to figure out the configuration with the fewest number of lines in the LDraw file. The differences are just too minor for that to be worth it.)

So the most basic way to get rid of a T-junction is to add a new triangle inside an existing quad or triangle. One thing that you DON'T want to do is convert a triangle into a quad in order to avoid a T-junction. This won't actually work right.

[[Image:T_Junction7.png]]In the example at the left, the correct thing to do is split the triangle into two separate triangles: A•B•D and B•C•D. If you create a quad A•B•C•D, the tracker might reject the part (degenerate quad), but even if it doesn't, it's bad. As I said above, the renderer will likely split the quad into two triangles. The thing is, there's no way to know how that split will go. So it could choose A•B•D and B•C•D, or it could choose A•B•C and A•C•D, which ends up being a triangle with a T-junction and a degenerate triangle (line). LDView will actually pull the D point out of the quad at load time and treat it as a triangle (and spit out a warning).

This all gets much more complicated when the T-junctions happen along the edges of primitives like disks. Sometimes it's not even possible to get rid of the T-junctions when using primitives, and at least with circular primitives, I think that it's better to use a circular primitive with a T-junction that can't be removed than it is to avoid the circular primitive in order to avoid the T-junction.

[[Category:Tutorials]]

Avoiding T-Junctions

2012-08-10T01:17:48Z

Timgould: moved Avoiding T-Junctions to Avoiding T-Junctions in LDraw parts: Using full tutorial name

#REDIRECT [[Avoiding T-Junctions in LDraw parts]]

T-Junction

2012-08-10T01:17:48Z

Timgould: moved Avoiding T-Junctions to Avoiding T-Junctions in LDraw parts: Using full tutorial name

T-Junctions in LDraw parts can often lead to unavoidable rendering artifacts, so it's best to avoid them when possible.

By Travis Cobbs.

=Avoiding T-junctions in LDraw parts=
==Definition==

A T-junction is a spot where two polygons meet along the edge of another polygon, like so: [[Image:T_Junction1.png]] If these occur in a random location along a diagonal edge, it's often the case that the precise coordinates of the junction cannot be put into the DAT file. Many people would agree that that would be bad. However, when they occur at precise coordinates, it's tempting to say that there's nothing wrong with them, since there shouldn't be any round-off problems. Unfortunately, when you go to arbitrary 3D views, this turns out not to be the case.

It turns out that a 3D rendering engine can only guarantee that a closed polygon mesh is tight (no visible gaps) if the mesh does not contain any T-junctions. The reason for this is that once you start rotating things in 3D, the precise coordinates stop being precise.

The following illustrates this problem:

[[Image:T_Junction2.png]]

Notice the white dots. If you view the file in wireframe, you'll see that these dots occur along the seams between polygons. Please note that the actual coordinates of all the points in the file are fine (as far as I know; I haven't checked, but I believe Mike). The dots are there because from that point of view, the edges are diagonal, and diagonal edges require rounding. Essentially, the rounding cannot be guaranteed to be the same on the polygons along the edge if those polygons don't share common end-points on both ends.

This may be difficult to understand. Hopefully the following will illustrate the point:

[[Image:T_Junction3.png]] [[Image:T_Junction3a.png]]These images were done in Microsoft Paint (then blown up by 800%), with two sets of lines that are designed to be right next to each other. The image on the left represents the T-Junction case. The one on the right represents the case without a T-junction. As you can see, there are gaps in the image on the left. This isn't quite the same as T-junctions in a part file, since the above sets of lines were drawn with 1 pixel difference. However, since 3D renderers are representing adjoining polygons with an infinitely thin edge between them, it actually works out to a very similar problem. (Note that the red line in the left image was actually drawn starting at the bottom-most green pixel, and the green line was then drawn with the same end-point.)

==Getting rid of T-junctions your LDraw part==

As far as I know, a T-junction in a triangle or quad can always be removed by the addition of one triangle. This can be tedious, but I don't know of any automated solution. Also, there are often better ways to get rid of T-junctions than adding a triangle. For example:

[[Image:T_Junction4.png]] [[Image:T_Junction5.png]] [[Image:T_Junction6.png]]

Notice that the bottom version is made up of 4 quads, while the middle version has 3 quads and 2 triangles. That makes the bottom version better, sort of. Most renderers will at some point divide all the quads into triangles, and both versions result in the same number of final triangles, so it's not necessarily as much better as it might look. (I mention this, because things get a whole lot more complicated as the shapes become more complex, and it's really not worth trying to figure out the configuration with the fewest number of lines in the LDraw file. The differences are just too minor for that to be worth it.)

So the most basic way to get rid of a T-junction is to add a new triangle inside an existing quad or triangle. One thing that you DON'T want to do is convert a triangle into a quad in order to avoid a T-junction. This won't actually work right.

[[Image:T_Junction7.png]]In the example at the left, the correct thing to do is split the triangle into two separate triangles: A•B•D and B•C•D. If you create a quad A•B•C•D, the tracker might reject the part (degenerate quad), but even if it doesn't, it's bad. As I said above, the renderer will likely split the quad into two triangles. The thing is, there's no way to know how that split will go. So it could choose A•B•D and B•C•D, or it could choose A•B•C and A•C•D, which ends up being a triangle with a T-junction and a degenerate triangle (line). LDView will actually pull the D point out of the quad at load time and treat it as a triangle (and spit out a warning).

This all gets much more complicated when the T-junctions happen along the edges of primitives like disks. Sometimes it's not even possible to get rid of the T-junctions when using primitives, and at least with circular primitives, I think that it's better to use a circular primitive with a T-junction that can't be removed than it is to avoid the circular primitive in order to avoid the T-junction.

[[Category:Tutorials]]

Category:Tutorials

2012-08-10T01:16:52Z

Timgould:

Collection of tutorials for LDraw. Feel free to improve these or add your own.

Also check out the [http://www.ldraw.org/article/58.html tutorials on the website] for links to other tutorials around the web.

[[category:Menu]]

Getting Started - Linux

2012-08-10T01:16:05Z

Timgould: /* Step 3: Dive in */

==Step 1: Download and Install the LDraw Library==

* Go to the [http://www.ldraw.org/downloads-2/downloads.html LDraw.org download page] and download the latest <code>complete.zip</code>
* Unzip <code>complete.zip</code> in the directory of your choice - we recommend <code>~/ldraw/</code> if you don't want to worry about file permissions.

==Step 2: Install LDCad==

* Go to [http://www.melkert.net/LDCad http://www.melkert.net/LDCad] and download the Linux version of LDCad
* Unzip the package into the directory of your choice
* Run LDCad
* When asked for the location of the LDraw Library, use the directory where you unzipped <code>complete.zip</code>.

==Step 2b: Other editors==

* The [http://konstruktor.influx.kr/ Konstruktor] editor is also under development and may offer an alternative to LDCad.

==Step 3: Dive in==

Learning how to use your new editor or understanding the LDraw file format may be a challenge, but with a little practice you will get the hang of it. Check out the tutorials [[:Category:Tutorials|on the wiki]] or [http://www.ldraw.org/article/58.html on the main website].

==Help!==

Need help with any of this? Visit the [http://forums.ldraw.org LDraw.org Forums] and ask a large group of users for help.

[[Category:Linux]]
[[Category:Tutorials]]

Getting Started - Linux

2012-08-10T01:14:01Z

Timgould: /* Step 2: Install LDCad */

==Step 1: Download and Install the LDraw Library==

* Go to the [http://www.ldraw.org/downloads-2/downloads.html LDraw.org download page] and download the latest <code>complete.zip</code>
* Unzip <code>complete.zip</code> in the directory of your choice - we recommend <code>~/ldraw/</code> if you don't want to worry about file permissions.

==Step 2: Install LDCad==

* Go to [http://www.melkert.net/LDCad http://www.melkert.net/LDCad] and download the Linux version of LDCad
* Unzip the package into the directory of your choice
* Run LDCad
* When asked for the location of the LDraw Library, use the directory where you unzipped <code>complete.zip</code>.

==Step 2b: Other editors==

* The [http://konstruktor.influx.kr/ Konstruktor] editor is also under development and may offer an alternative to LDCad.

==Step 3: Dive in==

Learning how to use your new editor or understanding the LDraw file format may be a challenge, but with a little practice you will get the hang of it.

==Help!==

Need help with any of this? Visit the [http://forums.ldraw.org LDraw.org Forums] and ask a large group of users for help.

[[Category:Linux]]
[[Category:Tutorials]]

Getting Started - Linux

2012-08-10T01:10:39Z

Timgould:

==Step 1: Download and Install the LDraw Library==

* Go to the [http://www.ldraw.org/downloads-2/downloads.html LDraw.org download page] and download the latest <code>complete.zip</code>
* Unzip <code>complete.zip</code> in the directory of your choice - we recommend <code>~/ldraw/</code> if you don't want to worry about file permissions.

==Step 2: Install LDCad==

* Go to [http://www.melkert.net/LDCad http://www.melkert.net/LDCad] and download the Linux version of LDCad
* Unzip the package into the directory of your choice
* Run LDCad
* When asked for the location of the LDraw Library, use the directory where you unzipped <code>complete.zip</code>.

==Step 3: Dive in==

Learning how to use your new editor or understanding the LDraw file format may be a challenge, but with a little practice you will get the hang of it.

==Help!==

Need help with any of this? Visit the [http://forums.ldraw.org LDraw.org Forums] and ask a large group of users for help.

[[Category:Linux]]
[[Category:Tutorials]]

Getting Started - Linux

2012-08-09T21:02:13Z

Timgould:

==Step 1: Download and Install the LDraw Library==

* Go to the [http://www.ldraw.org/downloads-2/downloads.html LDraw.org download page] and download the latest <code>complete.zip</code>
* Unzip <code>complete.zip</code> in the directory of your choice - we recommend <code>~/ldraw/</code> if you don't want to worry about file permissions.

==Step 2: Install LDCad==

* Go to [http://www.melkert.net/LDCad http://www.melkert.net/LDCad] and download the Linux version of LDCad
* Unzip the package into the directory of your choice
* Run LDCad
* When asked for the location of the LDraw Library, use the directory where you unzipped <code>complete.zip</code>.

==Step 3: Dive in==

Learning how to use your new editor or understanding the LDraw file format may be a challenge, but with a little practice you will get the hang of it.

==Help!==

Need help with any of this? Visit the [http://forums.ldraw.org LDraw.org Forums] and ask a large group of users for help.

Chromadepth 3D Glasses Tutorial

2012-08-06T05:49:35Z

Timgould:

{{OldArticle}}
By: [mailto:mikh2161@gmail.com Michael Horvath]

==Introduction:==
This tutorial describes how to render LDraw models so that they can be viewed in 3D using polarized glasses. Before proceeding with this tutorial, you should already know how to build models using MLCad and convert them to POV-Ray format using L3P.

==Background:==
Polarized glasses are a type of glasses that affect depth-perception by intercepting light in such a way that two-dimensional images appear three-dimensional to the eye. The perceived depth depends on the wavelength of the reflected light; blueish colors appear to be distant, redder colors appear to be near, greener colors appear to lie somewhere in the middle.

One manufacturer of such glasses is ChromaTek. You can learn more about their glasses by visiting [http://www.3dglassesonline.com/3d-chromadepth-glasses/index.html their website]. For more information on polarized glasses in general, you can read the [http://www.chromatek.com/Image_Design/image_design.shtml Open CyberHolographic Standard] (also located at the ChromaTek website).

 ''(This tutorial was written for L3P v1.3 and probably needs to be re-written for L3P v1.4.)''

# Convert your MLCAD model to POV-Ray format using L3P. Open the POV file in POV-Ray. Search within the file for light source statements (they should be near the end of the file) and delete any that you encounter.
# Locate the <tt>camera</tt> statement. It should be just above the lights, before the <tt>background</tt>, and should look something like this: // Camera (Latitude,Longitude,Radius = 30,45,-20)
camera {
#declare PCT = 20; // Percentage further away
#declare STEREO = 0; // Normal view
//#declare STEREO = degrees(atan2(1,12))/2; // Left view
//#declare STEREO = -degrees(atan2(1,12))/2; // Right view
location vaxis_rotate(<607.219,-575.974,-744.326>
+ PCT/100.0*<542.276,-442.766,-542.276>,
<-240101,-588126,240101>, STEREO)
sky -y
right -4/3*x
look_at <64.9436,-133.208,-202.05>
angle 67.3801
}
# Move the camera statement to the very top of the file, and insert the following code immediately after it: <nowiki>#declare lookFrom = ;
#declare lookAt = ;
#declare ChromaMaterial = #if (version >= 3.1) material { #end texture {
pigment {
gradient vnormalize(lookFrom lookAt)
color_map { [0 rgb z][1/2 rgb y][1 rgb x] }
scale vlength(lookFrom - lookAt) * 2
translate lookFrom * -1
}
finish {ambient 1}
} #if (version >= 3.1) } #end</nowiki>
# Look within the camera statement for the <tt>location</tt> and <tt>look_at</tt> keywords. Copy the part following the <tt>location</tt> keyword and paste it after the <tt>lookFrom</tt> keyword. Now, copy the part that follows the <tt>look_at</tt> keyword and paste it after the <tt>lookAt</tt> keyword. When you're done, it should look something like this: <nowiki>#declare lookFrom = vaxis_rotate(<607.219,-575.974,-744.326>
+ PCT/100.0*<542.276,-442.766,-542.276>,
<-240101,-588126,240101>, STEREO);
#declare lookAt = <64.9436,-133.208,-202.05>;</nowiki>
# Search for the very last <tt>object</tt> statement. It should be near the end of the POV file, just before the <tt>background</tt> statement. If the name of your model file is "castle.ldr", then the object statement should look something like this: object { castle #if (version >= 3.1) material #else texture #end { Color7 } }
# Modify the code so that the ChromaMaterial material is used instead of <tt>Color(n)</tt>. E.g.: object { castle #if (version >= 3.1) material #else texture #end { ChromaMaterial } }
# Now, search within the POV file for any other instances of a <tt>Color(n)</tt> texture being assigned to an object, and delete them. For example, if you find a line like this, delete it: <nowiki>#if (version >= 3.1) material #else texture #end { Color8 }</nowiki>
# You're finished! All you have to do now is render your image. The final rendered image should look something like this:<center>[[Image:Chromatek1.png]]</center>

[[Category:Tutorials]]

LDraw to SimCity 3000 Unlimited Tutorial

2012-08-06T05:49:25Z

Timgould:

{{OldArticle}}
By: [mailto:mikh2161@gmail.com Michael Horvath]

==Introduction:==

This tutorial instructs you on how to import '''LDraw''' models into '''SimCity 3000 Unlimited'''. You should already know how to build models using '''LDraw''' or '''MLCad''' and render them using '''POV-Ray'''. '''Maxis''', the makers of '''SimCity 3000 Unlimited''', have created their own tutorial on how to render objects and import them into the game. It is not required to complete this tutorial; but if you'd like to read it anyway, you can find it [http://simcity3000unlimited.ea.com/us/guide/tips/unlimited_tips/ccp1.phtml here].

==Required Software==
For starters, let's go over the programs involved: '''SimCity 3000 Urban Renewal Kit''' ('''SC3URK''') is a program created by '''Maxis''' that allows you to design and import your own buildings into '''SimCity 3000 Unlimited'''. It is not included on the '''SimCity 3000 Unlimited''' installation disk. Instead, it is available as a separate download from the '''SimCity''' website (see the Links section below). You will also need a paint program, such as '''Windows Paint'''.

==Links:==

# [http://simcity3000unlimited.ea.com/us/guide/ SimCity 3000 Home Page]
# [http://simcity3000unlimited.ea.com/us/simexchange/downloads/sc3krk/index.phtml SC3URK Download Page]

==Instructions:==

# Build a model in '''LDraw''' or '''MLCAD'''.
# Orient your completed model so that it is centered within the coordinate system, with the bottom of the model resting upon the x-z plane, as shown below:[[Image:ldr_mlcad_axes.png]] ''In the above image and for demonstration purposes, the x-axis is colored red, the y-axis is colored green, and the z-axis is colored blue. The coordinate axes will not appear when editing your own model.''
# Convert your model into a '''*.POV''' file using '''L3P'''.
# The lighting needs to be modified so that there are a total of six spotlights oriented according to the following scheme:[[Image:ldr_s3kurk_lighting.png]]Open up the '''*.POV''' file in '''POV-Ray''' and replace the light sources with the following code:
// Warm lights:
light_source
{
<0, 0, 100000,>
color rgb <255/255, 249/255, 232/255,>
spotlight
parallel
point_at <0, 0, 0,>
}
light_source
{
<0, 0, -100000,>
color rgb <255/255, 249/255, 232/255,>
spotlight
parallel
point_at <0, 0, 0,>
}

// Neutral lights:
light_source
{
<0, 0, 0,>
color rgb <198/255, 198/255, 198/255,> * 0.75
spotlight
parallel
point_at vaxis_rotate(<0, 100, 0,>, x, 30)
translate <0, -100000, 0,>
}
light_source
{
<0, 0, 0,>
color rgb <198/255, 198/255, 198/255,> * 0.75
spotlight
parallel
point_at vaxis_rotate(<0, 100, 0,>, x, -30)
translate <0, -100000, 0,>
}

// Cold lights:
light_source
{
<100000, 0, 0,>
color rgb <98/255, 98/255, 133/255,> * 1.3
spotlight
parallel
point_at <0, 0, 0,>
}
light_source
{
<-100000, 0, 0,>
color rgb <98/255, 98/255, 133/255,> * 1.3
spotlight
parallel
point_at <0, 0, 0,>
}

# Now, replace the background and camera with the following code: <nowiki>
// Background color
background {color rgb <1, 0, 1,>}

// Default tile size; 1 = 1x1 tile; 2 = 2x2 tile, etc.
#declare Tile = 4;

// Camera rotation angle around the vertical axis
#declare Rotate = 0;

// Camera:
camera
{
#local LegLength = sqrt(pow(640, 2) / 2) * 2;
orthographic
sky -y
up y * LegLength * Tile * image_height / image_width
right x * LegLength * Tile
location vaxis_rotate(<1, 0, 1,>, <1, 0, -1,>, 30) * LegLength * Tile
look_at <0, 0, 0,>
rotate y * Rotate
#if (frame_number > 0)
rotate y * 360/final_frame * (frame_number - 1)
#end
}
</nowiki>Change the '''TILE''' keyword to reflect the width of your building, measured in SimCity tiles. To preserve the proper scale, one SimCity tile should equal one LDraw baseplate.You can rotate the camera around the y-axis by changing the '''ROTATE''' keyword to an angle in degrees. For instance, if the camera normally faces the NW corner of your model, you can change the '''ROTATE''' keyword to equal '''180''' to have it face the SE corner of your model.
# Create a '''new text file''' and paste the following code into it: <nowiki>
;; SC3URK 128px x 512px Output Bitmap
Width = 128
Height = 512
Final_Frame = 4 ;; Number of frames/views
Final_Clock = 3 ;; Number of frames/views minus one
Output_File_Name = c:\lego\ldraw\images\
</nowiki>Save or rename this text file as '''LDR2SC3K.INI''' and place it within the '''RENDERER''' directory in your '''POV-Ray''' installation directory.This file determines the height and width dimensions of the final images that '''POV-Ray''' will generate, as well as the '''number''' of images (frames) that will be rendered. A total of four images will be rendered -- one for each direction: NW, NE, SW and SE. The images should be 128 pixels wide if your building is 1x1 tiles in size, 256 pixels wide if it is 2x2 tiles in size -- and so forth, increasing in width by 128 pixels for each additional tile. You will need to experiment in order to determine what values are suitable for the '''HEIGHT''' parameter, as they will vary depending on your building's height.The last line specifies the directory you would like the rendered images saved to. Change this to a preferred location. Make sure you leave a back-slash ('\') at the end of the path.
# To render your model, select '''RENDER''' from the '''POV-Ray''' menu. Then, select '''EDIT SETTINGS/RENDER'''. Where it says '''INI FILE''', click on '''BROWSE''' and find the '''LDR2SC3K.INI''' file. Once it's selected, click '''OK'''. Now click on '''SET BUT DON'T RENDER'''. This should bring you back to the main '''POV-Ray''' window. Now, click on the green '''RUN''' icon at the top of the screen. '''POV-Ray''' will now render your model and output the images into the directory you specified in '''LDR2SC3K.INI'''.
# If you are using '''BAT''' to import your images into '''SimCity 3000''' (i.e., not '''SimCity 3000 Unlimited'''), you will have to crop the images in a paint program so that they properly fit the template images included with the program (you can also find them on the SimCity web site). If you are using '''SC3URK''', instead (as is recommended), you will need to crop your images so that your building is aligned with the sides and bottom, like this:[[Image:ldr_yellowcastle_sc3k.png]]
# Run '''SC3URK''' and import the images. Make sure you import them in the correct order.
# After you've imported them into '''SimCity 3000''' or '''SimCity 3000 Unlimited''', an in-game screenshot featuring your completed building should look something like this:[[Image:ldr_sc3urk.jpg]]That's it! You're done!

----

==Alternative instructions:==

As an alternative to the above steps, you can also install a set of '''*.INC''' and '''*.INI''' files that I have created for you and conveniently included in a ZIP archive. This is a shortcut and will allow you to achieve the same results.

# Follow steps 1 through 3 in the first tutorial.
# Download and decompress the [http://www.mediafire.com/file/jj4llmyzem3/ldr_ldr2sc3k_v1_2_0.zip archive]. Place the '''*.INC''' file within the '''INCLUDE''' directory of your '''POV-Ray''' installation directory. Place the '''*.INI''' file within the '''RENDERER''' directory of your POV-Ray installation directory.
# Open up your '''*.POV''' file in '''POV-Ray''' and replace the background, camera, and light sources with the following declarations and include-statements: <nowiki>
// Default tile size; 1 = 1x1 tile; 2 = 2x2 tile, etc.
#declare Tile = 4;

// Camera rotation angle around the vertical axis
#declare Rotate = 0;

// SC3URK Scene Description Language
#include "LDR2SC3K.INC"
</nowiki>Change the '''TILE''' declaration to reflect however wide your building is (in tiles):
# Select the '''*.INI''' file from the '''POV-Ray''' '''RENDER''' menu (see step 6, above). Render the images by pressing '''RENDER'''.
# Crop and import your building images into '''SimCity 3000''', as described in steps 7 and 8, above.

T-Junction

2012-08-04T07:17:04Z

Timgould:

T-Junctions in LDraw parts can often lead to unavoidable rendering artifacts, so it's best to avoid them when possible.

By Travis Cobbs.

=Avoiding T-Junctions in LDraw Parts=
==Definition==

A T-junction is a spot where two polygons meet along the edge of another polygon, like so: [[Image:T_Junction1.png]] If these occur in a random location along a diagonal edge, it's often the case that the precise coordinates of the junction cannot be put into the DAT file. Many people would agree that that would be bad. However, when they occur at precise coordinates, it's tempting to say that there's nothing wrong with them, since there shouldn't be any round-off problems. Unfortunately, when you go to arbitrary 3D views, this turns out not to be the case.

It turns out that a 3D rendering engine can only guarantee that a closed polygon mesh is tight (no visible gaps) if the mesh does not contain any T-junctions. The reason for this is that once you start rotating things in 3D, the precise coordinates stop being precise.

The following illustrates this problem:

[[Image:T_Junction2.png]]

Notice the white dots. If you view the file in wireframe, you'll see that these dots occur along the seams between polygons. Please note that the actual coordinates of all the points in the file are fine (as far as I know; I haven't checked, but I believe Mike). The dots are there because from that point of view, the edges are diagonal, and diagonal edges require rounding. Essentially, the rounding cannot be guaranteed to be the same on the polygons along the edge if those polygons don't share common end-points on both ends.

This may be difficult to understand. Hopefully the following will illustrate the point:

[[Image:T_Junction3.png]] [[Image:T_Junction3a.png]]These images were done in Microsoft Paint (then blown up by 800%), with two sets of lines that are designed to be right next to each other. The image on the left represents the T-Junction case. The one on the right represents the case without a T-junction. As you can see, there are gaps in the image on the left. This isn't quite the same as T-junctions in a part file, since the above sets of lines were drawn with 1 pixel difference. However, since 3D renderers are representing adjoining polygons with an infinitely thin edge between them, it actually works out to a very similar problem. (Note that the red line in the left image was actually drawn starting at the bottom-most green pixel, and the green line was then drawn with the same end-point.)

==Getting Rid of T-Junctions your LDraw Part==

As far as I know, a T-junction in a triangle or quad can always be removed by the addition of one triangle. This can be tedious, but I don't know of any automated solution. Also, there are often better ways to get rid of T-junctions than adding a triangle. For example:

[[Image:T_Junction4.png]] [[Image:T_Junction5.png]] [[Image:T_Junction6.png]]

Notice that the bottom version is made up of 3 quads, while the middle version has 3 quads and 2 triangles. That makes the bottom version better, sort of. Most renderers will at some point divide all the quads into triangles, and both versions result in the same number of final triangles, so it's not necessarily as much better as it might look. (I mention this, because things get a whole lot more complicated as the shapes become more complex, and it's really not worth trying to figure out the configuration with the fewest number of lines in the LDraw file. The differences are just too minor for that to be worth it.)

So the most basic way to get rid of a T-junction is to add a new triangle inside an existing quad or triangle. One thing that you DON'T want to do is convert a triangle into a quad in order to avoid a T-junction. This won't actually work right.

[[Image:T_Junction7.png]]In the example at the left, the correct thing to do is split the triangle into two separate triangles: A•B•D and B•C•D. If you create a quad A•B•C•D, the tracker might reject the part (degenerate quad), but even if it doesn't, it's bad. As I said above, the renderer will likely split the quad into two triangles. The thing is, there's no way to know how that split will go. So it could choose A•B•D and B•C•D, or it could choose A•B•C and A•C•D, which ends up being a triangle with a T-junction and a degenerate triangle (line). LDView will actually pull the D point out of the quad at load time and treat it as a triangle (and spit out a warning).

This all gets much more complicated when the T-junctions happen along the edges of primitives like disks. Sometimes it's not even possible to get rid of the T-junctions when using primitives, and at least with circular primitives, I think that it's better to use a circular primitive with a T-junction that can't be removed than it is to avoid the circular primitive in order to avoid the T-junction.

[[Category:Tutorials]]

LDraw to SimCity 3000 Unlimited Tutorial

2012-07-31T10:14:54Z

Timgould:

By: [mailto:mikh2161@gmail.com Michael Horvath]

==Introduction:==

This tutorial instructs you on how to import '''LDraw''' models into '''SimCity 3000 Unlimited'''. You should already know how to build models using '''LDraw''' or '''MLCad''' and render them using '''POV-Ray'''. '''Maxis''', the makers of '''SimCity 3000 Unlimited''', have created their own tutorial on how to render objects and import them into the game. It is not required to complete this tutorial; but if you'd like to read it anyway, you can find it [http://simcity3000unlimited.ea.com/us/guide/tips/unlimited_tips/ccp1.phtml here].

==Required Software==
For starters, let's go over the programs involved: '''SimCity 3000 Urban Renewal Kit''' ('''SC3URK''') is a program created by '''Maxis''' that allows you to design and import your own buildings into '''SimCity 3000 Unlimited'''. It is not included on the '''SimCity 3000 Unlimited''' installation disk. Instead, it is available as a separate download from the '''SimCity''' website (see the Links section below). You will also need a paint program, such as '''Windows Paint'''.

==Links:==

# [http://simcity3000unlimited.ea.com/us/guide/ SimCity 3000 Home Page]
# [http://simcity3000unlimited.ea.com/us/simexchange/downloads/sc3krk/index.phtml SC3URK Download Page]

==Instructions:==

# Build a model in '''LDraw''' or '''MLCAD'''.
# Orient your completed model so that it is centered within the coordinate system, with the bottom of the model resting upon the x-z plane, as shown below:[[Image:ldr_mlcad_axes.png]] ''In the above image and for demonstration purposes, the x-axis is colored red, the y-axis is colored green, and the z-axis is colored blue. The coordinate axes will not appear when editing your own model.''
# Convert your model into a '''*.POV''' file using '''L3P'''.
# The lighting needs to be modified so that there are a total of six spotlights oriented according to the following scheme:[[Image:ldr_s3kurk_lighting.png]]Open up the '''*.POV''' file in '''POV-Ray''' and replace the light sources with the following code:
// Warm lights:
light_source
{
<0, 0, 100000,>
color rgb <255/255, 249/255, 232/255,>
spotlight
parallel
point_at <0, 0, 0,>
}
light_source
{
<0, 0, -100000,>
color rgb <255/255, 249/255, 232/255,>
spotlight
parallel
point_at <0, 0, 0,>
}

// Neutral lights:
light_source
{
<0, 0, 0,>
color rgb <198/255, 198/255, 198/255,> * 0.75
spotlight
parallel
point_at vaxis_rotate(<0, 100, 0,>, x, 30)
translate <0, -100000, 0,>
}
light_source
{
<0, 0, 0,>
color rgb <198/255, 198/255, 198/255,> * 0.75
spotlight
parallel
point_at vaxis_rotate(<0, 100, 0,>, x, -30)
translate <0, -100000, 0,>
}

// Cold lights:
light_source
{
<100000, 0, 0,>
color rgb <98/255, 98/255, 133/255,> * 1.3
spotlight
parallel
point_at <0, 0, 0,>
}
light_source
{
<-100000, 0, 0,>
color rgb <98/255, 98/255, 133/255,> * 1.3
spotlight
parallel
point_at <0, 0, 0,>
}

# Now, replace the background and camera with the following code: <nowiki>
// Background color
background {color rgb <1, 0, 1,>}

// Default tile size; 1 = 1x1 tile; 2 = 2x2 tile, etc.
#declare Tile = 4;

// Camera rotation angle around the vertical axis
#declare Rotate = 0;

// Camera:
camera
{
#local LegLength = sqrt(pow(640, 2) / 2) * 2;
orthographic
sky -y
up y * LegLength * Tile * image_height / image_width
right x * LegLength * Tile
location vaxis_rotate(<1, 0, 1,>, <1, 0, -1,>, 30) * LegLength * Tile
look_at <0, 0, 0,>
rotate y * Rotate
#if (frame_number > 0)
rotate y * 360/final_frame * (frame_number - 1)
#end
}
</nowiki>Change the '''TILE''' keyword to reflect the width of your building, measured in SimCity tiles. To preserve the proper scale, one SimCity tile should equal one LDraw baseplate.You can rotate the camera around the y-axis by changing the '''ROTATE''' keyword to an angle in degrees. For instance, if the camera normally faces the NW corner of your model, you can change the '''ROTATE''' keyword to equal '''180''' to have it face the SE corner of your model.
# Create a '''new text file''' and paste the following code into it: <nowiki>
;; SC3URK 128px x 512px Output Bitmap
Width = 128
Height = 512
Final_Frame = 4 ;; Number of frames/views
Final_Clock = 3 ;; Number of frames/views minus one
Output_File_Name = c:\lego\ldraw\images\
</nowiki>Save or rename this text file as '''LDR2SC3K.INI''' and place it within the '''RENDERER''' directory in your '''POV-Ray''' installation directory.This file determines the height and width dimensions of the final images that '''POV-Ray''' will generate, as well as the '''number''' of images (frames) that will be rendered. A total of four images will be rendered -- one for each direction: NW, NE, SW and SE. The images should be 128 pixels wide if your building is 1x1 tiles in size, 256 pixels wide if it is 2x2 tiles in size -- and so forth, increasing in width by 128 pixels for each additional tile. You will need to experiment in order to determine what values are suitable for the '''HEIGHT''' parameter, as they will vary depending on your building's height.The last line specifies the directory you would like the rendered images saved to. Change this to a preferred location. Make sure you leave a back-slash ('\') at the end of the path.
# To render your model, select '''RENDER''' from the '''POV-Ray''' menu. Then, select '''EDIT SETTINGS/RENDER'''. Where it says '''INI FILE''', click on '''BROWSE''' and find the '''LDR2SC3K.INI''' file. Once it's selected, click '''OK'''. Now click on '''SET BUT DON'T RENDER'''. This should bring you back to the main '''POV-Ray''' window. Now, click on the green '''RUN''' icon at the top of the screen. '''POV-Ray''' will now render your model and output the images into the directory you specified in '''LDR2SC3K.INI'''.
# If you are using '''BAT''' to import your images into '''SimCity 3000''' (i.e., not '''SimCity 3000 Unlimited'''), you will have to crop the images in a paint program so that they properly fit the template images included with the program (you can also find them on the SimCity web site). If you are using '''SC3URK''', instead (as is recommended), you will need to crop your images so that your building is aligned with the sides and bottom, like this:[[Image:ldr_yellowcastle_sc3k.png]]
# Run '''SC3URK''' and import the images. Make sure you import them in the correct order.
# After you've imported them into '''SimCity 3000''' or '''SimCity 3000 Unlimited''', an in-game screenshot featuring your completed building should look something like this:[[Image:ldr_sc3urk.jpg]]That's it! You're done!

----

==Alternative instructions:==

As an alternative to the above steps, you can also install a set of '''*.INC''' and '''*.INI''' files that I have created for you and conveniently included in a ZIP archive. This is a shortcut and will allow you to achieve the same results.

# Follow steps 1 through 3 in the first tutorial.
# Download and decompress the [http://www.mediafire.com/file/jj4llmyzem3/ldr_ldr2sc3k_v1_2_0.zip archive]. Place the '''*.INC''' file within the '''INCLUDE''' directory of your '''POV-Ray''' installation directory. Place the '''*.INI''' file within the '''RENDERER''' directory of your POV-Ray installation directory.
# Open up your '''*.POV''' file in '''POV-Ray''' and replace the background, camera, and light sources with the following declarations and include-statements: <nowiki>
// Default tile size; 1 = 1x1 tile; 2 = 2x2 tile, etc.
#declare Tile = 4;

// Camera rotation angle around the vertical axis
#declare Rotate = 0;

// SC3URK Scene Description Language
#include "LDR2SC3K.INC"
</nowiki>Change the '''TILE''' declaration to reflect however wide your building is (in tiles):
# Select the '''*.INI''' file from the '''POV-Ray''' '''RENDER''' menu (see step 6, above). Render the images by pressing '''RENDER'''.
# Crop and import your building images into '''SimCity 3000''', as described in steps 7 and 8, above.

LDraw to SimCity 3000 Unlimited Tutorial

2012-07-31T10:14:11Z

Timgould: Created page with "By: [mailto:mikh2161@gmail.com Michael Horvath] ==Introduction:== This tutorial instructs you on how to import '''LDraw''' models into '''SimCity 3000 Unlimited'''. You shou..."

By: [mailto:mikh2161@gmail.com Michael Horvath]

==Introduction:==

This tutorial instructs you on how to import '''LDraw''' models into '''SimCity 3000 Unlimited'''. You should already know how to build models using '''LDraw''' or '''MLCad''' and render them using '''POV-Ray'''. '''Maxis''', the makers of '''SimCity 3000 Unlimited''', have created their own tutorial on how to render objects and import them into the game. It is not required to complete this tutorial; but if you'd like to read it anyway, you can find it [http://simcity3000unlimited.ea.com/us/guide/tips/unlimited_tips/ccp1.phtml here].

==Required Software==
For starters, let's go over the programs involved: '''SimCity 3000 Urban Renewal Kit''' ('''SC3URK''') is a program created by '''Maxis''' that allows you to design and import your own buildings into '''SimCity 3000 Unlimited'''. It is not included on the '''SimCity 3000 Unlimited''' installation disk. Instead, it is available as a separate download from the '''SimCity''' website (see the Links section below). You will also need a paint program, such as '''Windows Paint'''.

==Links:==

# [http://simcity3000unlimited.ea.com/us/guide/ SimCity 3000 Home Page]
# [http://simcity3000unlimited.ea.com/us/simexchange/downloads/sc3krk/index.phtml SC3URK Download Page]

==Instructions:==

# Build a model in '''LDraw''' or '''MLCAD'''.
# Orient your completed model so that it is centered within the coordinate system, with the bottom of the model resting upon the x-z plane, as shown below:[[Image:ldr_mlcad_axes.png]] ''In the above image and for demonstration purposes, the x-axis is colored red, the y-axis is colored green, and the z-axis is colored blue. The coordinate axes will not appear when editing your own model.''
# Convert your model into a '''*.POV''' file using '''L3P'''.
# The lighting needs to be modified so that there are a total of six spotlights oriented according to the following scheme:[[Image:ldr_s3kurk_lighting.png]]Open up the '''*.POV''' file in '''POV-Ray''' and replace the light sources with the following code:

// Warm lights:

light_source

{

<0, 0, 100000,>

color rgb <255/255, 249/255, 232/255,>

spotlight

parallel

point_at <0, 0, 0,>

}

light_source

{

<0, 0, -100000,>

color rgb <255/255, 249/255, 232/255,>

spotlight

parallel

point_at <0, 0, 0,>

}

// Neutral lights:

light_source

{

<0, 0, 0,>

color rgb <198/255, 198/255, 198/255,> * 0.75

spotlight

parallel

point_at vaxis_rotate(<0, 100, 0,>, x, 30)

translate <0, -100000, 0,>

}

light_source

{

<0, 0, 0,>

color rgb <198/255, 198/255, 198/255,> * 0.75

spotlight

parallel

point_at vaxis_rotate(<0, 100, 0,>, x, -30)

translate <0, -100000, 0,>

}

// Cold lights:

light_source

{

<100000, 0, 0,>

color rgb <98/255, 98/255, 133/255,> * 1.3

spotlight

parallel

point_at <0, 0, 0,>

}

light_source

{

<-100000, 0, 0,>

color rgb <98/255, 98/255, 133/255,> * 1.3

spotlight

parallel

point_at <0, 0, 0,>

}

# Now, replace the background and camera with the following code: <nowiki>

// Background color

background {color rgb <1, 0, 1,>}

// Default tile size; 1 = 1x1 tile; 2 = 2x2 tile, etc.

#declare Tile = 4;

// Camera rotation angle around the vertical axis

#declare Rotate = 0;

// Camera:

camera

{

#local LegLength = sqrt(pow(640, 2) / 2) * 2;

orthographic

sky -y

up y * LegLength * Tile * image_height / image_width

right x * LegLength * Tile

location vaxis_rotate(<1, 0, 1,>, <1, 0, -1,>, 30) * LegLength * Tile

look_at <0, 0, 0,>

rotate y * Rotate

#if (frame_number > 0)

rotate y * 360/final_frame * (frame_number - 1)

#end

}

</nowiki>Change the '''TILE''' keyword to reflect the width of your building, measured in SimCity tiles. To preserve the proper scale, one SimCity tile should equal one LDraw baseplate.You can rotate the camera around the y-axis by changing the '''ROTATE''' keyword to an angle in degrees. For instance, if the camera normally faces the NW corner of your model, you can change the '''ROTATE''' keyword to equal '''180''' to have it face the SE corner of your model.
# Create a '''new text file''' and paste the following code into it: <nowiki>

;; SC3URK 128px x 512px Output Bitmap

Width = 128

Height = 512

Final_Frame = 4 ;; Number of frames/views

Final_Clock = 3 ;; Number of frames/views minus one

Output_File_Name = c:\lego\ldraw\images\

</nowiki>Save or rename this text file as '''LDR2SC3K.INI''' and place it within the '''RENDERER''' directory in your '''POV-Ray''' installation directory.This file determines the height and width dimensions of the final images that '''POV-Ray''' will generate, as well as the '''number''' of images (frames) that will be rendered. A total of four images will be rendered -- one for each direction: NW, NE, SW and SE. The images should be 128 pixels wide if your building is 1x1 tiles in size, 256 pixels wide if it is 2x2 tiles in size -- and so forth, increasing in width by 128 pixels for each additional tile. You will need to experiment in order to determine what values are suitable for the '''HEIGHT''' parameter, as they will vary depending on your building's height.The last line specifies the directory you would like the rendered images saved to. Change this to a preferred location. Make sure you leave a back-slash ('\') at the end of the path.
# To render your model, select '''RENDER''' from the '''POV-Ray''' menu. Then, select '''EDIT SETTINGS/RENDER'''. Where it says '''INI FILE''', click on '''BROWSE''' and find the '''LDR2SC3K.INI''' file. Once it's selected, click '''OK'''. Now click on '''SET BUT DON'T RENDER'''. This should bring you back to the main '''POV-Ray''' window. Now, click on the green '''RUN''' icon at the top of the screen. '''POV-Ray''' will now render your model and output the images into the directory you specified in '''LDR2SC3K.INI'''.
# If you are using '''BAT''' to import your images into '''SimCity 3000''' (i.e., not '''SimCity 3000 Unlimited'''), you will have to crop the images in a paint program so that they properly fit the template images included with the program (you can also find them on the SimCity web site). If you are using '''SC3URK''', instead (as is recommended), you will need to crop your images so that your building is aligned with the sides and bottom, like this:[[Image:ldr_yellowcastle_sc3k.png]]
# Run '''SC3URK''' and import the images. Make sure you import them in the correct order.
# After you've imported them into '''SimCity 3000''' or '''SimCity 3000 Unlimited''', an in-game screenshot featuring your completed building should look something like this:[[Image:ldr_sc3urk.jpg]]That's it! You're done!

----

==Alternative instructions:==

As an alternative to the above steps, you can also install a set of '''*.INC''' and '''*.INI''' files that I have created for you and conveniently included in a ZIP archive. This is a shortcut and will allow you to achieve the same results.

# Follow steps 1 through 3 in the first tutorial.
# Download and decompress the [http://www.mediafire.com/file/jj4llmyzem3/ldr_ldr2sc3k_v1_2_0.zip archive]. Place the '''*.INC''' file within the '''INCLUDE''' directory of your '''POV-Ray''' installation directory. Place the '''*.INI''' file within the '''RENDERER''' directory of your POV-Ray installation directory.
# Open up your '''*.POV''' file in '''POV-Ray''' and replace the background, camera, and light sources with the following declarations and include-statements: <nowiki>

// Default tile size; 1 = 1x1 tile; 2 = 2x2 tile, etc.

#declare Tile = 4;

// Camera rotation angle around the vertical axis

#declare Rotate = 0;

// SC3URK Scene Description Language

#include "LDR2SC3K.INC"

</nowiki>Change the '''TILE''' declaration to reflect however wide your building is (in tiles):
# Select the '''*.INI''' file from the '''POV-Ray''' '''RENDER''' menu (see step 6, above). Render the images by pressing '''RENDER'''.
# Crop and import your building images into '''SimCity 3000''', as described in steps 7 and 8, above.

[[Category:Tutorials]]

Cleaning LDraw Files for Export

2012-07-31T10:11:12Z

Timgould: Created page with "LDraw models are great to look at, but are generally inappropriate for real-time rendering tasks such as video games. Here's why. The main issue is detail. LDraw models are h..."

LDraw models are great to look at, but are generally inappropriate for real-time rendering tasks such as video games. Here's why.

The main issue is detail. LDraw models are highly accurate representations of real Lego parts. Each part can have lots of minute details, and the number of parts in a single large model can be quite huge! This amount of detail translates into lots and lots of polygons, which is the main limiter of how well a real-time rendering application will run.

The second issue is hidden objects: LDraw models are made up of multiple smaller parts. These parts are assembled as they are, with no modification. Thus, all the inner bits and pieces (such as studs) that are visible when viewing the part by itself but invisible when viewing the entire model are still there. That means there's lots of detail (and thus polygons) in the model that will never see the light of day!

The third issue is redundancy: Let's take for example a model composed of two identical bricks stacked on top of each other. The bricks are flush with each other such that the bottom surface of the top object is pressed against the top surface of the bottom object. You could say that the objects occupy the same place, or are coincident. In reality, there's a tiny gap between these surfaces where a small amount of air can pass through. In computer modeling, however, it is often useful to disregard these differences and simply make all points and surfaces mathematically perfect. While this is trivial to do and can lead to pleasing results, it introduces a problem. Each part has a set of matching surfaces and vertices shared by the other part. Some of these surfaces and vertices are in fact duplicates. The duplicate elements no longer serve a useful purpose, and end up merely taking up much needed space in the model file. There's a strong need to get rid of these redundant, wasteful elements.

I know of two tentative, partially automated ways of addressing these issues that, when used in conjunction with each other, might eliminate the above problems: removing internal faces using MeshLab and using LDBoxer to convert parts to simpler, lighter versions. I will not discuss these in detail. They are, however, addressed in the links at the end of this article. Simple poly-reduction techniques such as Blender's "Decimate" operation will not work, as they choose polygons more or less randomly, and don't differentiate between the "inside" and "outside" of a model.

Note that there is an additional issue related to MeshLab's internal face reduction approach: back-face culling (BFC). When cleaning parts from a model, Meshlab requires that the vertices of the triangles be "wound" properly. Winding is what allows the program (and other programs that use 3D models) to determine the surface normal when not specifically defined, and thus (roughly) the "outside" and "inside" of the model. If the vertices are not wound properly, the program will get confused and behave improperly. Unfortunately, in the case of LDraw models only a small minority of parts have been validated as "BFC certified", and thus wound properly. This fact peculiar to LDraw models will likely make the approach untenable in the majority cases.

==Links:==

* [http://meshlabstuff.blogspot.com/search/label/mesh%20cleaning How to remove internal faces with MeshLab]
* [http://home.swipnet.se/simlego/ldraw/ldboxer/ldboxer.htm LDraw Boxer]

[[Category:Tutorials]]

Chromadepth 3D Glasses Tutorial

2012-07-31T10:08:31Z

Timgould:

By: [mailto:mikh2161@gmail.com Michael Horvath]

==Introduction:==
This tutorial describes how to render LDraw models so that they can be viewed in 3D using polarized glasses. Before proceeding with this tutorial, you should already know how to build models using MLCad and convert them to POV-Ray format using L3P.

==Background:==
Polarized glasses are a type of glasses that affect depth-perception by intercepting light in such a way that two-dimensional images appear three-dimensional to the eye. The perceived depth depends on the wavelength of the reflected light; blueish colors appear to be distant, redder colors appear to be near, greener colors appear to lie somewhere in the middle.

One manufacturer of such glasses is ChromaTek. You can learn more about their glasses by visiting [http://www.3dglassesonline.com/3d-chromadepth-glasses/index.html their website]. For more information on polarized glasses in general, you can read the [http://www.chromatek.com/Image_Design/image_design.shtml Open CyberHolographic Standard] (also located at the ChromaTek website).

 ''(This tutorial was written for L3P v1.3 and probably needs to be re-written for L3P v1.4.)''

# Convert your MLCAD model to POV-Ray format using L3P. Open the POV file in POV-Ray. Search within the file for light source statements (they should be near the end of the file) and delete any that you encounter.
# Locate the <tt>camera</tt> statement. It should be just above the lights, before the <tt>background</tt>, and should look something like this: // Camera (Latitude,Longitude,Radius = 30,45,-20)
camera {
#declare PCT = 20; // Percentage further away
#declare STEREO = 0; // Normal view
//#declare STEREO = degrees(atan2(1,12))/2; // Left view
//#declare STEREO = -degrees(atan2(1,12))/2; // Right view
location vaxis_rotate(<607.219,-575.974,-744.326>
+ PCT/100.0*<542.276,-442.766,-542.276>,
<-240101,-588126,240101>, STEREO)
sky -y
right -4/3*x
look_at <64.9436,-133.208,-202.05>
angle 67.3801
}
# Move the camera statement to the very top of the file, and insert the following code immediately after it: <nowiki>#declare lookFrom = ;
#declare lookAt = ;
#declare ChromaMaterial = #if (version >= 3.1) material { #end texture {
pigment {
gradient vnormalize(lookFrom lookAt)
color_map { [0 rgb z][1/2 rgb y][1 rgb x] }
scale vlength(lookFrom - lookAt) * 2
translate lookFrom * -1
}
finish {ambient 1}
} #if (version >= 3.1) } #end</nowiki>
# Look within the camera statement for the <tt>location</tt> and <tt>look_at</tt> keywords. Copy the part following the <tt>location</tt> keyword and paste it after the <tt>lookFrom</tt> keyword. Now, copy the part that follows the <tt>look_at</tt> keyword and paste it after the <tt>lookAt</tt> keyword. When you're done, it should look something like this: <nowiki>#declare lookFrom = vaxis_rotate(<607.219,-575.974,-744.326>
+ PCT/100.0*<542.276,-442.766,-542.276>,
<-240101,-588126,240101>, STEREO);
#declare lookAt = <64.9436,-133.208,-202.05>;</nowiki>
# Search for the very last <tt>object</tt> statement. It should be near the end of the POV file, just before the <tt>background</tt> statement. If the name of your model file is "castle.ldr", then the object statement should look something like this: object { castle #if (version >= 3.1) material #else texture #end { Color7 } }
# Modify the code so that the ChromaMaterial material is used instead of <tt>Color(n)</tt>. E.g.: object { castle #if (version >= 3.1) material #else texture #end { ChromaMaterial } }
# Now, search within the POV file for any other instances of a <tt>Color(n)</tt> texture being assigned to an object, and delete them. For example, if you find a line like this, delete it: <nowiki>#if (version >= 3.1) material #else texture #end { Color8 }</nowiki>
# You're finished! All you have to do now is render your image. The final rendered image should look something like this:<center>[[Image:Chromatek1.png]]</center>

[[Category:Tutorials]]

Chromadepth 3D Glasses Tutorial

2012-07-31T10:08:16Z

Timgould:

=Polarized Glasses Tutorial=
By: [mailto:mikh2161@gmail.com Michael Horvath]

==Introduction:==
This tutorial describes how to render LDraw models so that they can be viewed in 3D using polarized glasses. Before proceeding with this tutorial, you should already know how to build models using MLCad and convert them to POV-Ray format using L3P.

==Background:==
Polarized glasses are a type of glasses that affect depth-perception by intercepting light in such a way that two-dimensional images appear three-dimensional to the eye. The perceived depth depends on the wavelength of the reflected light; blueish colors appear to be distant, redder colors appear to be near, greener colors appear to lie somewhere in the middle.

One manufacturer of such glasses is ChromaTek. You can learn more about their glasses by visiting [http://www.3dglassesonline.com/3d-chromadepth-glasses/index.html their website]. For more information on polarized glasses in general, you can read the [http://www.chromatek.com/Image_Design/image_design.shtml Open CyberHolographic Standard] (also located at the ChromaTek website).

 ''(This tutorial was written for L3P v1.3 and probably needs to be re-written for L3P v1.4.)''

# Convert your MLCAD model to POV-Ray format using L3P. Open the POV file in POV-Ray. Search within the file for light source statements (they should be near the end of the file) and delete any that you encounter.
# Locate the <tt>camera</tt> statement. It should be just above the lights, before the <tt>background</tt>, and should look something like this: // Camera (Latitude,Longitude,Radius = 30,45,-20)
camera {
#declare PCT = 20; // Percentage further away
#declare STEREO = 0; // Normal view
//#declare STEREO = degrees(atan2(1,12))/2; // Left view
//#declare STEREO = -degrees(atan2(1,12))/2; // Right view
location vaxis_rotate(<607.219,-575.974,-744.326>
+ PCT/100.0*<542.276,-442.766,-542.276>,
<-240101,-588126,240101>, STEREO)
sky -y
right -4/3*x
look_at <64.9436,-133.208,-202.05>
angle 67.3801
}
# Move the camera statement to the very top of the file, and insert the following code immediately after it: <nowiki>#declare lookFrom = ;
#declare lookAt = ;
#declare ChromaMaterial = #if (version >= 3.1) material { #end texture {
pigment {
gradient vnormalize(lookFrom lookAt)
color_map { [0 rgb z][1/2 rgb y][1 rgb x] }
scale vlength(lookFrom - lookAt) * 2
translate lookFrom * -1
}
finish {ambient 1}
} #if (version >= 3.1) } #end</nowiki>
# Look within the camera statement for the <tt>location</tt> and <tt>look_at</tt> keywords. Copy the part following the <tt>location</tt> keyword and paste it after the <tt>lookFrom</tt> keyword. Now, copy the part that follows the <tt>look_at</tt> keyword and paste it after the <tt>lookAt</tt> keyword. When you're done, it should look something like this: <nowiki>#declare lookFrom = vaxis_rotate(<607.219,-575.974,-744.326>
+ PCT/100.0*<542.276,-442.766,-542.276>,
<-240101,-588126,240101>, STEREO);
#declare lookAt = <64.9436,-133.208,-202.05>;</nowiki>
# Search for the very last <tt>object</tt> statement. It should be near the end of the POV file, just before the <tt>background</tt> statement. If the name of your model file is "castle.ldr", then the object statement should look something like this: object { castle #if (version >= 3.1) material #else texture #end { Color7 } }
# Modify the code so that the ChromaMaterial material is used instead of <tt>Color(n)</tt>. E.g.: object { castle #if (version >= 3.1) material #else texture #end { ChromaMaterial } }
# Now, search within the POV file for any other instances of a <tt>Color(n)</tt> texture being assigned to an object, and delete them. For example, if you find a line like this, delete it: <nowiki>#if (version >= 3.1) material #else texture #end { Color8 }</nowiki>
# You're finished! All you have to do now is render your image. The final rendered image should look something like this:<center>[[Image:Chromatek1.png]]</center>

[[Category:Tutorials]]

Chromadepth 3D Glasses Tutorial

2012-07-31T10:07:44Z

Timgould: Created page with "=Polarized Glasses Tutorial= By: [mailto:mikh2161@gmail.com Michael Horvath] ==Introduction:== This tutorial describes how to render LDraw models so that they can be viewed i..."

=Polarized Glasses Tutorial=
By: [mailto:mikh2161@gmail.com Michael Horvath]

==Introduction:== This tutorial describes how to render LDraw models so that they can be viewed in 3D using polarized glasses. Before proceeding with this tutorial, you should already know how to build models using MLCad and convert them to POV-Ray format using L3P.

==Background:== Polarized glasses are a type of glasses that affect depth-perception by intercepting light in such a way that two-dimensional images appear three-dimensional to the eye. The perceived depth depends on the wavelength of the reflected light; blueish colors appear to be distant, redder colors appear to be near, greener colors appear to lie somewhere in the middle.

One manufacturer of such glasses is ChromaTek. You can learn more about their glasses by visiting [http://www.3dglassesonline.com/3d-chromadepth-glasses/index.html their website]. For more information on polarized glasses in general, you can read the [http://www.chromatek.com/Image_Design/image_design.shtml Open CyberHolographic Standard] (also located at the ChromaTek website).

 ''(This tutorial was written for L3P v1.3 and probably needs to be re-written for L3P v1.4.)''

# Convert your MLCAD model to POV-Ray format using L3P. Open the POV file in POV-Ray. Search within the file for light source statements (they should be near the end of the file) and delete any that you encounter.
# Locate the <tt>camera</tt> statement. It should be just above the lights, before the <tt>background</tt>, and should look something like this: // Camera (Latitude,Longitude,Radius = 30,45,-20)
camera {
#declare PCT = 20; // Percentage further away
#declare STEREO = 0; // Normal view
//#declare STEREO = degrees(atan2(1,12))/2; // Left view
//#declare STEREO = -degrees(atan2(1,12))/2; // Right view
location vaxis_rotate(<607.219,-575.974,-744.326>
+ PCT/100.0*<542.276,-442.766,-542.276>,
<-240101,-588126,240101>, STEREO)
sky -y
right -4/3*x
look_at <64.9436,-133.208,-202.05>
angle 67.3801
}
# Move the camera statement to the very top of the file, and insert the following code immediately after it: <nowiki>#declare lookFrom = ;
#declare lookAt = ;
#declare ChromaMaterial = #if (version >= 3.1) material { #end texture {
pigment {
gradient vnormalize(lookFrom lookAt)
color_map { [0 rgb z][1/2 rgb y][1 rgb x] }
scale vlength(lookFrom - lookAt) * 2
translate lookFrom * -1
}
finish {ambient 1}
} #if (version >= 3.1) } #end</nowiki>
# Look within the camera statement for the <tt>location</tt> and <tt>look_at</tt> keywords. Copy the part following the <tt>location</tt> keyword and paste it after the <tt>lookFrom</tt> keyword. Now, copy the part that follows the <tt>look_at</tt> keyword and paste it after the <tt>lookAt</tt> keyword. When you're done, it should look something like this: <nowiki>#declare lookFrom = vaxis_rotate(<607.219,-575.974,-744.326>
+ PCT/100.0*<542.276,-442.766,-542.276>,
<-240101,-588126,240101>, STEREO);
#declare lookAt = <64.9436,-133.208,-202.05>;</nowiki>
# Search for the very last <tt>object</tt> statement. It should be near the end of the POV file, just before the <tt>background</tt> statement. If the name of your model file is "castle.ldr", then the object statement should look something like this: object { castle #if (version >= 3.1) material #else texture #end { Color7 } }
# Modify the code so that the ChromaMaterial material is used instead of <tt>Color(n)</tt>. E.g.: object { castle #if (version >= 3.1) material #else texture #end { ChromaMaterial } }
# Now, search within the POV file for any other instances of a <tt>Color(n)</tt> texture being assigned to an object, and delete them. For example, if you find a line like this, delete it: <nowiki>#if (version >= 3.1) material #else texture #end { Color8 }</nowiki>
# You're finished! All you have to do now is render your image. The final rendered image should look something like this:<center>[[Image:Chromatek1.png]]</center>

[[Category:Tutorials]]

T-Junction

2012-07-31T10:05:08Z

Timgould:

=Avoiding T-Junctions in LDraw Parts=

T-Junctions in LDraw parts can often lead to unavoidable rendering artifacts, so it's best to avoid them when possible.

By Travis Cobbs.

==Definition==

A T-junction is a spot where two polygons meet along the edge of another polygon, like so: [[Image:T_Junction1.png]] If these occur in a random location along a diagonal edge, it's often the case that the precise coordinates of the junction cannot be put into the DAT file. Many people would agree that that would be bad. However, when they occur at precise coordinates, it's tempting to say that there's nothing wrong with them, since there shouldn't be any round-off problems. Unfortunately, when you go to arbitrary 3D views, this turns out not to be the case.

It turns out that a 3D rendering engine can only guarantee that a closed polygon mesh is tight (no visible gaps) if the mesh does not contain any T-junctions. The reason for this is that once you start rotating things in 3D, the precise coordinates stop being precise.

The following illustrates this problem:

[[Image:T_Junction2.png]]

Notice the white dots. If you view the file in wireframe, you'll see that these dots occur along the seams between polygons. Please note that the actual coordinates of all the points in the file are fine (as far as I know; I haven't checked, but I believe Mike). The dots are there because from that point of view, the edges are diagonal, and diagonal edges require rounding. Essentially, the rounding cannot be guaranteed to be the same on the polygons along the edge if those polygons don't share common end-points on both ends.

This may be difficult to understand. Hopefully the following will illustrate the point:

[[Image:T_Junction3.png]] [[Image:T_Junction3a.png]]These images were done in Microsoft Paint (then blown up by 800%), with two sets of lines that are designed to be right next to each other. The image on the left represents the T-Junction case. The one on the right represents the case without a T-junction. As you can see, there are gaps in the image on the left. This isn't quite the same as T-junctions in a part file, since the above sets of lines were drawn with 1 pixel difference. However, since 3D renderers are representing adjoining polygons with an infinitely thin edge between them, it actually works out to a very similar problem. (Note that the red line in the left image was actually drawn starting at the bottom-most green pixel, and the green line was then drawn with the same end-point.)

==Getting Rid of T-Junctions your LDraw Part==

As far as I know, a T-junction in a triangle or quad can always be removed by the addition of one triangle. This can be tedious, but I don't know of any automated solution. Also, there are often better ways to get rid of T-junctions than adding a triangle. For example:

[[Image:T_Junction4.png]] [[Image:T_Junction5.png]] [[Image:T_Junction6.png]]

Notice that the bottom version is made up of 3 quads, while the middle version has 3 quads and 2 triangles. That makes the bottom version better, sort of. Most renderers will at some point divide all the quads into triangles, and both versions result in the same number of final triangles, so it's not necessarily as much better as it might look. (I mention this, because things get a whole lot more complicated as the shapes become more complex, and it's really not worth trying to figure out the configuration with the fewest number of lines in the LDraw file. The differences are just too minor for that to be worth it.)

So the most basic way to get rid of a T-junction is to add a new triangle inside an existing quad or triangle. One thing that you DON'T want to do is convert a triangle into a quad in order to avoid a T-junction. This won't actually work right.

[[Image:T_Junction7.png]]In the example at the left, the correct thing to do is split the triangle into two separate triangles: A•B•D and B•C•D. If you create a quad A•B•C•D, the tracker might reject the part (degenerate quad), but even if it doesn't, it's bad. As I said above, the renderer will likely split the quad into two triangles. The thing is, there's no way to know how that split will go. So it could choose A•B•D and B•C•D, or it could choose A•B•C and A•C•D, which ends up being a triangle with a T-junction and a degenerate triangle (line). LDView will actually pull the D point out of the quad at load time and treat it as a triangle (and spit out a warning).

This all gets much more complicated when the T-junctions happen along the edges of primitives like disks. Sometimes it's not even possible to get rid of the T-junctions when using primitives, and at least with circular primitives, I think that it's better to use a circular primitive with a T-junction that can't be removed than it is to avoid the circular primitive in order to avoid the T-junction.

[[Category:Tutorials]]

T-Junction

2012-07-31T10:04:16Z

Timgould:

=Avoiding T-Junctions in LDraw Parts=

==Home text==

T-Junctions in LDraw parts can often lead to unavoidable rendering artifacts, so it's best to avoid them when possible.

By Travis Cobbs.

==Body text==

'''Definition'''

A T-junction is a spot where two polygons meet along the edge of another polygon, like so: [[Image:T_Junction1.png]] If these occur in a random location along a diagonal edge, it's often the case that the precise coordinates of the junction cannot be put into the DAT file. Many people would agree that that would be bad. However, when they occur at precise coordinates, it's tempting to say that there's nothing wrong with them, since there shouldn't be any round-off problems. Unfortunately, when you go to arbitrary 3D views, this turns out not to be the case.

It turns out that a 3D rendering engine can only guarantee that a closed polygon mesh is tight (no visible gaps) if the mesh does not contain any T-junctions. The reason for this is that once you start rotating things in 3D, the precise coordinates stop being precise.

The following illustrates this problem:

[[Image:T_Junction2.png]]

Notice the white dots. If you view the file in wireframe, you'll see that these dots occur along the seams between polygons. Please note that the actual coordinates of all the points in the file are fine (as far as I know; I haven't checked, but I believe Mike). The dots are there because from that point of view, the edges are diagonal, and diagonal edges require rounding. Essentially, the rounding cannot be guaranteed to be the same on the polygons along the edge if those polygons don't share common end-points on both ends.

This may be difficult to understand. Hopefully the following will illustrate the point:

[[Image:T_Junction3.png]] [[Image:T_Junction3a.png]]These images were done in Microsoft Paint (then blown up by 800%), with two sets of lines that are designed to be right next to each other. The image on the left represents the T-Junction case. The one on the right represents the case without a T-junction. As you can see, there are gaps in the image on the left. This isn't quite the same as T-junctions in a part file, since the above sets of lines were drawn with 1 pixel difference. However, since 3D renderers are representing adjoining polygons with an infinitely thin edge between them, it actually works out to a very similar problem. (Note that the red line in the left image was actually drawn starting at the bottom-most green pixel, and the green line was then drawn with the same end-point.)

'''Getting Rid of T-Junctions your LDraw Part'''

As far as I know, a T-junction in a triangle or quad can always be removed by the addition of one triangle. This can be tedious, but I don't know of any automated solution. Also, there are often better ways to get rid of T-junctions than adding a triangle. For example:

[[Image:T_Junction4.png]] [[Image:T_Junction5.png]] [[Image:T_Junction6.png]]

Notice that the bottom version is made up of 3 quads, while the middle version has 3 quads and 2 triangles. That makes the bottom version better, sort of. Most renderers will at some point divide all the quads into triangles, and both versions result in the same number of final triangles, so it's not necessarily as much better as it might look. (I mention this, because things get a whole lot more complicated as the shapes become more complex, and it's really not worth trying to figure out the configuration with the fewest number of lines in the LDraw file. The differences are just too minor for that to be worth it.)

So the most basic way to get rid of a T-junction is to add a new triangle inside an existing quad or triangle. One thing that you DON'T want to do is convert a triangle into a quad in order to avoid a T-junction. This won't actually work right.

[[Image:T_Junction7.png]]In the example at the left, the correct thing to do is split the triangle into two separate triangles: A•B•D and B•C•D. If you create a quad A•B•C•D, the tracker might reject the part (degenerate quad), but even if it doesn't, it's bad. As I said above, the renderer will likely split the quad into two triangles. The thing is, there's no way to know how that split will go. So it could choose A•B•D and B•C•D, or it could choose A•B•C and A•C•D, which ends up being a triangle with a T-junction and a degenerate triangle (line). LDView will actually pull the D point out of the quad at load time and treat it as a triangle (and spit out a warning).

This all gets much more complicated when the T-junctions happen along the edges of primitives like disks. Sometimes it's not even possible to get rid of the T-junctions when using primitives, and at least with circular primitives, I think that it's better to use a circular primitive with a T-junction that can't be removed than it is to avoid the circular primitive in order to avoid the T-junction.

[[Category:Tutorials]]

T-Junction

2012-07-31T10:03:42Z

Timgould: From old site - 526

Template:OldArticle

2012-07-31T09:15:41Z

Timgould:

'''Warning!''' ''This article is a legacy article from the old site. It is provided for historical context and information may no longer be relavent.''

----

Template:OldArticle

2012-07-31T09:15:14Z

Timgould: Created page with "''This article is a legacy article from the old site. It is provided for historical context and information may no longer be relavent.'' ----"

''This article is a legacy article from the old site. It is provided for historical context and information may no longer be relavent.''

----

Conversion 101

2012-07-31T09:11:22Z

Timgould:

{{OldArticle}}

By: [mailto:info@digitalbricks.nl Jeroen de Haan] and [mailto:sink@countersinkdg.com Jake McKee] Posted: May 11, 2002 Version: v1 rev.1 110202

=Knowledge Requirements=
What your reading now is a beginners guide to L3P/L3PAO and POV-Ray. It assumes you have some knowledge of and experience with LDraw and one or more of its editors (such as MLCAD, LeoCAD, BrickDraw3D, etc) and creating models. What it wants to provide is a step by step guide of converting LDraw-models to POV-files and rendering them and what options you have when converting or rendering. What you won't find here is how to create models or parts.

Some chapters are on the practical side; you will do things after reading it. Other chapters are more theoretical, for example about cameras and lenses or color and light. Please read these chapters too. We try to make them as short and "light" as possible but they are important to understand some of the functions and options of L3P and POV-Ray.

=Chapter 1: Introduction=
So you have made some models; your own or existing Lego models. Now you want to have a nice picture of it, like the ones you see on Brickshelf or on other people's websites. However, your editor for LDraw can't so how do people do that? What you need is three programs and some additional files:

# L3P: a program that converts .DAT, .LDR and .MPD files to .POV (the native file format for POV-Ray)
# L3P AddOn (or L3PAO for short): a graphic interface for L3P
# POV-Ray: a freeware program to ray trace POV-files
# The LGEO-files for POV-Ray.

L3P is a DOS-program. It uses switches to call certain options. So for example, when you want your model with a certain camera position and background color you have to type the following in the DOS-prompt: L3P.exe tp-7745.dat tp-7745.pov -cc0,-96,-250 -ca45 -b0.000,0.000,0.251 -o You have to know (all) the options and their acronyms and when you make a typo, (and who doesn't now and then) you have to type it all over again. Or if you want a batch of models you have to retype the whole line over and over again.

This is why J. Boen created L3P AddOn, a graphic interface for L3P where you can turn on or off options in an easy way AND can save these options in "scenes" or snapshots.

POV-Ray is a freeware program to create and render computer generated pictures or animations. POV-Ray has no graphical interface in the sense that you see what you create; it has a source window where you type text commands and you can see what you created when you render the picture. Luckily, you don't have to learn all these commands; L3P creates a ready to render POV-file!

The LGEO-files for POV-Ray are files that POV-Ray uses to substitute some of the LDraw parts. The LGEO-files look better; cylinders are rounder, sloped bricks have that sandpaper structure, etc. They are also harder to render for POV-Ray; you will need lots of memory to use them.

However, before you can make a nice rendering of your model you have to download the above mentioned software. Best place to start is http://www.ldraw.org/download/win/. Go to the download section and click the appropriate links. We going to guide you with installing the programs but please read the installation guides of each program carefully!

=Chapter 2: Downloading and installing L3P, L3PAO and POV-Ray and LGEO=

'''LGEO-files''' We will start with the easiest: the LGEO-files.

# Go to http://www.el-lutzo.de/lego/lgeo.html
# Download the LGEO POV-Ray Library (Â±548kB)
# Place the Zip-file in the LDraw-directory an unzip it.
# That's it (for now)!

'''L3P''' L3P comes in two flavors: a 16-bit version and a 32-bit version. We recommend the latter because it is a bit faster, can handle long directory names (but no long filenames!) and can handle large LDraw files.

# Go to the [/modules.php?op=modload&name=Downloads&file=index Download] section
# Download L3P.zip.
# After downloading L3P.ZIP place the ZIP-file in the LDRAW-directory and unzip it. There are now two files in the LDRAW\L3P directory: L3P.EXE and L3P.TXT.
# DOS has to know where it can find L3P. Open a simple text editor like Notepad and open the AUTOEXEC.BAT or type "EDIT C:\AUTOEXEC.BAT" in the DOS-prompt.
# There probably will be a line starting with "set PATH=%PATH...". Place your cursor at the end of that. Now type the following sentence: ;C:\LDRAW\L3P (see below) and hit "Return" or "Enter".

[[Image:l3ppath.png]]

6. Now L3P has to know where it can find the LDraw parts and models. On the new line type:

<code> SET LDRAWDIR=C:\LDRAW (see below) </code> [[Image:l3pldrawdir.png]]

assuming the LDraw-directory is there. If you have placed it somewhere else please type the correct directory tree after C:\

7. L3P also needs to know where the LGEO-files are so in a new line under the SET LDRAWDIR line type:

<code> SET LGEODIR=c:\ldraw\lgeo </code>

Now every time you start up, DOS will read these commands and "know" where L3P is and where to find the LDraw parts and LGEO-files.

8. So, before going further with the L3PAO installation, please restart Windows.

'''L3PAO'''

# L3PAO.ZIP contains three files that should be unzipped in a temporally directory.
# Double click the SETUP.EXE and follow the instructions on screen. It is very simple. All you have to do is to point to the directory where L3PAO should be. By default, this is Program Files\L3PAO but the L3PAO manual recommends the same directory as where L3P is placed. So, hit the change directory-button and change the directory to c:\LDRAW\L3P.
# Now click the button with the computer icon on it. L3PAO will be installed. When finished it is ready to use, no restart needed.
# When you open L3PAO for the first time, it wants to know were it can find L3P (choose the LDRAW/L3P directory), Ledit (in the LDRAW directory) and LGEO-parts. Please point to the right directory.
# If you haven't installed POV-Ray and you open L3PAO, you will get a warning about that. Ignore it, close L3PAO and read on...

'''POV-Ray''' POV-Ray comes as POVWIN3.EXE. Download it and place it in a temporary directory. Now follow these 10 steps:

# Double click POVWIN3.EXE. You will be asked if you want to install POV-Ray: Click OK. The License Agreements opens now, read it and close it.
# A window opens asking if you agree with the agreement. Click Yes.
# The installer now asks where to place POV-Ray. By default, this is in the Program Files directory. Click OK if that is OK with you or choose an other directory.
# The installer will place an older version in a backup directory if you want (and have a older version). Choose Yes if you want to place the older version in a backup directory and No if you don't have a older version or don't want a backup of it.
# After copying the files in the right directories, the installer wants to know where to place the shortcut in the Start Menu. Click OK if you are happy with the default or choose an other place.
# The installer can place a shortcut on the desktop. Click Yes or No.
# By default, double clicking a POV-file will just open the file (click Yes). You can choose (but I don't recommend) to choose for double click is open and render. If you really really really want that, click No. By the way: as the window states: clicking with the right mouse button will open a menu where you can choose between Edit or Render.
# Next question: do you want a default directory for rendered files? It's up to you: choose Yes or No. Remember that if you choose No that POV-Ray will place the rendered file in the same directory as the POV-file, which can result in, files scattered all over your hard disk. (I chose Yes).
# A reminder
# Do you want a small demonstration? Click Yes.

Well that was easy wasn't it? You are ready to go now!

==Tips==

# Keep an eye on the various lugnet newsgroups for software updates: lugnet.cad.ray (for POV-Ray), lugnet.cad (for the others) or check ldraw.org.
# Lugnet.cad is also the place to post questions. However, before posting a question do a search to find out if no one posted the same question before you.

=Chapter 3: First conversion and rendering=
All the software is installed and you are ready to go! From the Start menu, choose L3P Add-On. The program starts and will show the following window:

[[Image:PIC0201.png]]

'''The L3PAO Interface''' Across the top you see three menu-items: File, Tools and Help. Below this are two text fields: the Model File (input) and POV-Ray Output File (output). Then there is the "switchboard" which is divided in 3 columns: camera, lights and other commands. Below these three columns is the "Generated Command Line"-box. This is where you can see (but not edit) the command line, which will be sent to L3P when you hit the "Run L3P" button bottom right. And lastly, the "Exit" button next to the "Run L3P" button, which will simply close the application.

The commands in the three "switchboard" columns will be covered in detail throughout this tutorial. Some of the more advanced topics are not covered. They will be discussed in other tutorials.

Alright, let's get started!

First, we need to load a .dat or .ldr model. To do this, use the "Model File" pull-down menu. Find a model file on your computer, by hitting the "..."-button to the right of the pop-up. You will be presented with a standard Open window where you can browse your computer. Throughout this tutorial, we will use the CAR.DAT, which is located in the LDRAW\MODELS-directory on your computer. This file is copied on your hard disk by the LDraw installer.

Because it is the first time you use L3PAO click the "..." button next to the "Model File"-pop-up. Browse to the LDRAW\MODELS-directory, click the CAR.DAT file and click "Open". The POV-file will be generated in the same directory as the DAT-file, unless you choose to specify a different location. For this example, we will not.

Uncheck "render upon complete" located near the bottom of L3PAO. Now click the "Run L3P" button. A DOS command window will appear and you will be able to watch the L3P commands run. However, if you have a fast computer, the box will disappear before you noticed it was there!

So now it is time to make your first rendering! Open the LDRAW\MODELS folder from your desktop and double click the CAR.POV file. The POV-Ray program will open, and will display the POV-Ray source code.

Before we get into any detail about POV-Ray, follow these instructions:

# On the top left-hand side, there is a pull-down menu with a series of dimensions. Choose 320 x 240, NO AA
# Hit the Start/Run button at the top of the interface to kick off your very first rendering
# POV-Ray will double check the code and prepare to render the car.pov file.
# After a few seconds (depending on your computer speed and the size of the file) a new window will open and line for line your first ray-traced (rendered) LEGO image appears!

=Chapter 4: A better first rendering=

[[Image:CAR.png]]

Yikes! It isn't what you hoped it would be, is it? It is a bit dark ...sort of a "car floating in space. Well you are right... the car is floating in space!

When making LDraw models, you usually don't need to define floors or backgrounds. Ldraw models look fine floating in space because of the flat, 2-Dimensional nature of the look. However, when you create a fully ray-traced model, you see something much closer to items in the real world that you see every day. When you see this "real" image, you expect it to also appear as though it is in a real environment. So let's fix this!

Open L3PAO again and choose the CAR.DAT again. If you look in the right side column, you will see two options: background (-b) and floor (-f) Click the checkbox to select background. The default background color in L3PAO is black,however, for our new rendering we will choose a different color. Click on the big black square, and a color picker window will open. Choose a nice shade of blue from the predefined colors. Click "OK".

Now select the floor option. By default, the floor is a light shade of gray, but we have some options to change that. There is a pull-down menu were you can choose between "g" (gray) or "c" (checkered, like a chess board).

In addition, there is a box with "Y" above it. This is the distance between the model and the floor. By default, this number is zero and this means the lowest part of your model will touch the floor. You can adjust this distance to make different effects. For instance, if you wanted to render an airplane or other flying object, you can lower the floor to make the model appear to be flying.

For our rendering select the "g" (gray) floor option, and leave the Y field blank. This will provide a rendering of the car sitting on a gray floor.Now, let's see what these new changes do for the rendering. Before we convert the file with these new options, let's change the "output name" of the file, to avoid overwriting our original car.pov file. In the "POV-Ray Output File" field at the top of the interface, change the name CAR.POV to CAR01.POV.

Now we are all set, so hit "Run L3P", and when it is done converting, switch back to POV-Ray, load the new CAR01.POV file, and Hit the "Start/Run" button to render. Note if you check off "Render upon complete" in L3PAO. L3PAO will open POV-Ray for you automatically and render the image using the last setting that POV-Ray had.

The result should look something like this:

[[Image:CAR01.png]]

Ah, that looks much better!

Because we have added the added floor, much more light will reflect back on the car, so the car looks much better. In addition, the car casts shadows on the floor so you get a lifelike image. The background will reflect light in the same manner as the floor, but since the background color is blue, the light being reflected is also somewhat blue. You can always change this by changing the background color to white.

Next stop: camera and lenses!

=Chapter 5: Camera and lenses (part 1)=

For a picture, you need three things: a model, light and a camera. Leave one out and the will be no picture (a Zen Buddhist would say you also need someone to watch the picture but more on that in the tutorial "Zen and the Art of LDraw).

With what we have rendered so far, you don't need to think about lights and camera placement. L3P very kindly places both of them for you at "fixed" locations. However, many times, you will want to change them to better suit your needs. So let's dive into camera placement and how L3P knows where to place it!

Before we start actually talking about the camera, we need to make sure that we understand the world the camera lives in, so to speak.

L3P uses the same coordinate system as LDraw. Remember those X, Y, Z axes from math class? Well, they're back! The X axis can be though of as the left to right plane, Y is the up to down plane, and Z is the forward to back plane. X and Z are parallel to the floor, while Y is perpendicular.

All three axes have both a positive and negative direction. Each axes changes from positive to negative at the center point of the globe. LDraw's coordinate system defines the axes in the following way:

+X (or simply X): Moving along the X axis to the right

-X: Moving along the X axis to the left

+ Y: Moving along the Y axis upwards

-Y: Moving along the Y axis downwards

+Z: Moving along the Z axis into the background

-Z: Moving along the Z axis into the foreground

If you take a look at the picture below, you will see all three axes, as well as a "globe" that is formed around them. This globe is the key to understanding how to move the camera and lights. L3P considers the model to be placed inside this globe, with the center point of the model's bounding box at the same place as the center point of the globe. (For reference, the Bounding Box is an imaginary box that the model fits in exactly. The top of the box lays on top of the highest point of the model, the bottom at the lowest point, and so on.)

[[Image:L3GLOBE2.png]]

Based on this globe system, the camera and lights can be easily placed by specifying Latitude, Longitude, and Radius (also known as polar coordinates).

Latitude is in the range from -90 degrees (south, along the positive y-axis) to 90 degrees (north, along the negative y-axis). Zero degrees is at the equator. Longitude is in the range from -180 to 180, where 0 degrees is along the negative z-axis. 90 degrees (east) is then along the positive x-axis and -90 degrees (west) is along the negative x-axis.

The basic LDraw views can be represented by these Latitude, Longitude pairs: Front=0,0 Right=0,-90 Left=0,90 Back=0,180 Over=90,0 Under=-90,0.

By now, you are probably asking, "This is great and all, but how do I move the camera around?" So let's dive into it!

The camera is placed at a certain distance from the model, which is called the "radius". By default, L3P calculates the radius so that the model fits very tightly in the rendering window. If you look at your last rendering, you see that the roof of the car is almost at the edge of the rendering window as is the bumper. If you want to specify a different camera globe position, L3P wants to know three things: the latitude (north or south position), longitude (east or west position) and radius (camera distance). As you can see in your last rendering, L3P calculates the radius so, that the model fits almost exactly in the picture. If you want you can move the camera away from the model so there is more space around the picture. The amount you give is a percentage.

By default L3P will place the camera as close as possible to the model. The viewing direction will be parallel to the direction given by the latitude (<la>) and longitude (<lo>). This won't necessarily be through the globe's center (also the model's center).

Think of the camera view towards the model as a funnel, with the point of funnel at the camera lens and the open end pointing towards the model. The funnel will be rotated so that its centerline is parallel to the direction vector defined by <la> and <lo> coordinates. L3P will move the funnel towards the model until it cannot come any closer.

The rendered image may look a bit distorted when the camera is moved that close, but this is to minimize the waste of empty rendered area. However, to get a nicer looking image (and a better look at the shadows) it may actually be better to have some amount of space around the model. To add this space, simply move the camera away from the model along the direction vector. If you specify a negative radius, e.g. -20, the camera will be moved 20% further away.

Yeah, yeah, you just want to do more rendering right? So let's do!

Open L3PAO, select CAR.DAT again and change the output name from to CAR02.POV Now go to the left column in the "switchboard" and check the -cg box. In the three input boxes, type in 0, 0, and -10 from left to right. Don't forget to add a floor and a background! Hit "Run L3P", and then render the new CAR02.POV file It will look like this:

[[Image:CAR02.png]]

Do you see what you did? You positioned the camera at the front of the model, and moved the camera back 10%. Fun, eh?

Now experiment for yourself on views. Try some different latitude and longitude settings to get a good feel of the polar coordinate system.

As an added feature of L3PAO, there is a "View Preset" pull-down menu that offers several standard views. These presets are already set to use the correct latitude, longitude, and radius to render some standard angles. You can use these as-is, or choose a preset and change the parameters a bit.

=Chapter 6: Camera and lenses (part 2)=

The radius (distance) of the camera from the model is calculated by L3P automatically for you. The camera radius depends on two things: the size of the model and the camera angle (or actually camera lens angle).

Camera angle, you ask? The lens of a camera has a certain angle, which determine what is visible and what is not. Basically how far to either side the camera can see. Human eyes have a viewing angle of 45 degrees, while the default camera angle in L3P is 67 degrees. Look at the picture below.

[[Image:camera.png]]

Lenses have their own characteristics: The normal lens (45Â°) will give a normal view. The telelens (<45Â°) will even the perspective: when using an extreme telelens you won't have perspective at all and all objects will have the same size; objects in the front and in the back of the picture. The wide lens (>45Â°) will distort the perspective: objects in the front look extremely big while objects in the back are very small, even in short distances.

Let's say the camera in the pictures above has a fixed distance towards a, b and c. The first camera has a standard lens. Not all the objects are visible (from this distance). The second lens is a tele-lens; only a small part of the picture is visible. Sports and wildlife photographers use this kind of lenses because you can get very "close" to an object from a distance (zoom in). The last lens is a wide- or fisheye lens; all the objects are visible. This is used in landscape and interior photography because you can get a lot on a picture without taking too much distance.

L3P uses the size of the model and the camera angle to calculate the radius. Lets say the two outer c's are the outer most part of a model. If you want to use a 45 degrees lens (as in the first camera), you have to move from the object. When using a 15 degrees lens you also have to move but a bit more extreme. In the last picture, you have to move to the model a bit.

Confused? Well let's try how it looks.

Open the CAR.DAT in L3PAO, add a floor and background and make 3 POV-files using Camera Globe Positions:

30,45,0 and Camera Angle 10 for CARCA010.POV

30,45,0 and Camera Angle 45 for CARCA045.POV

30,45,0 and Camera Angle 100 for CARCA100.POV

Open POV-Ray and render the pictures one by one.

The three pictures look like this:

[[Image:CARca010.png]]

This is the image rendered at a 10 degrees camera angle. You notice that the perspective lines are almost parallel. This is great when you want to render building steps of a model. The camera radius is roughly 1453 LDraw units (a 1 x 1 Brick is 24 LDraw units high).

[[Image:CARca045.png]]

This is the image rendered at 45 degrees camera angle. It has a much more life-like perspective. The camera radius is now just 334 LDraw units.

[[Image:CARca100.png]]

And last: the image rendered at a 100 degrees camera angle. You will notice that the picture is quite different: you can see the horizon now because the camera is closer and lower to the floor, which causes the car to look a bit odd. You can see how distorted the perspective is: the two red studs on right side of the bonnet are almost twice as large as the two studs on the left side. The camera is now only 194 LDraw units away.

If you look at the shadows on the floor, you will notice that these are different too. This is because, by default, L3P places 3 lights on fixed globe locations and at the same radius as the camera. Therefore, in the CARca045 image the lights are very far away and lit a large part of the floor while in the CARca100 image the camera, thus the lights are very close to the model, and a much smaller part of the floor is lit. Hence, the floor looks darker on the horizon.

=Chapter 7: Taking the camera out of the globe=

The default Camera Globe position is nice for pictures of the outside of a model. But what if you want a picture from within a model, almost as though you were inside the model looking out? You could change the radius to very small negative number so the camera will be in the model but the outcome will be very unpredictable. Therefore, it is better to take the camera from the globe so to speak and give it a fixed location. Instead of using the Camera Globe Position, we are going to use the Camera Coordinates in this chapter.

To get started, we need two coordinates: the camera coordinate and a "look at" point: the point where the camera will look at (or point at). These coordinates are LDraw coordinates so it is easy to determinate these.

Open the CAR.DAT in your LDraw editor (because I use and know MLCad best I will use that in this example but any other editor will do).

Place a 1 x 1 Brick inside the car above the chair at a height of a minifig's head. Make a note of the coordinates, which we will call -cc (it will be something like 0, -72, 10). Now place a 1 x 1 Brick in front of the car approximately at the same height as the one inside the car. You can place it a bit lower than the one inside, but don't over do it. Make a note of the coordinates, which we will call -cla (it will be something like 0, -56, -310). Delete both 1 x 1 Bricks and close the editor, without saving CAR.DAT.

Open L3PAO and open the CAR.DAT. Add a floor and background. Select the Camera Coordinates box (-cc), and fill in the coordinates in the three fields. Now select the Camera Look At box (-cla) and fill in the coordinates in the three fields. Change the output name to CARCC.DAT. Click "Run L3P" and open the .POV file.

After rendering, it will look like this.

[[Image:CARcc.png]]

Now you know what a mini-fig would see when driving a car! You can see the steering wheel and the reflection of the drivers seat in the window. You will have noticed that the time it took to render was considerable longer than the other pictures. This is because POV-Ray had to render through the windscreen and has to calculate all the refractions and reflections.

Now let's do this again, but from the outside to the inside of the car, like a car promotion brochure.

Open the CAR.DAT again in an LDraw editor. Select the steering wheel and make a note of its coordinates (0, -16, -30) , which will be the Look At coordinates (-cla).

Place a 1 x 1 Brick outside the car at the height of the roof and by the door. Make a note its coordinates (80, -80, 20), which will be the Camera Coordinates (-cc).

Now close the editor (again, don't save) and open L3PAO. Open the car, fill in the coordinates in the right fields. Choose 45 as camera angle (-ca). Select a floor and a blue background. Change the output file to CARCC2.POV.

Before you run L3P, we are going to save all these options in a "Scene".

Open the File menu and click "Save Scene". A standard Save as... window opens with L3P as directory (don't change that!). Now save the scene as CARCC2.xxx. If you were to close L3P (don't, but let's say) and want to use the same settings/options, all you have to do is open a DAT/LDR file, select "Open Scene" from the File menu and you are ready to go! No need to write everything down!

Hit "Run L3P", exit L3PAO and open CARCC2.POV in POV-Ray. Hit the "Run" button and wait...

[[Image:CARcc2a.png]]

The above image is the result. Because the rotation point of the Steering Wheel is at the bottom of the part, we are looking at the bottom of the car, or in other words: the center of the picture is not the steering wheel.

The good news is, is that we saved the options (phew!) and don't have to open the car in an editor to determine the coordinates.

Open L3PAO, load CAR.DAT and choose "Open Scene" from the File menu. Open the CARCC2.xxx. You see that all the parameters you used last time are back! Now all you have to do is to change the Y coordinate of the Look At point. Let's try two plate heights (or 32 LDraw units). So change the -16 in the second Look At box to -32.

Change the output name to CARCC3.POV, hit "Run L3P", exit L3PAO and open CARCC3.POV in POV-Ray. Hit the "Run" button and wait again while the image renders.

[[Image:CARcc2b.png]]

Yes, that is much better! The steering wheel is more in the center of the picture now.

Tips

# Start working out the Camera Globe position. Use the "car in the globe" picture to determine the position of the camera. Start with simple models first.
# Use the camera angle creatively but with care: use normal or tele-lenses (<50 degrees) for model presentation. Use a wider lens (>60 degrees) to add dynamics to a model or scene or to make it more "dramatic".
# Creation should be 90% Inspiration and 10% Transpiration. Look at real life pictures of objects similar to your model: how did other photographers take their picture? What was their point of view: low (or frog-view), normal viewing height or from a higher point (birds eye). Or think mini-fig height. Use a mini-fig to determine the camera coordinates.

[[Category:Tutorials]]

Conversion 101

2012-07-31T09:08:25Z

Timgould:

By: [mailto:info@digitalbricks.nl Jeroen de Haan] and [mailto:sink@countersinkdg.com Jake McKee] Posted: May 11, 2002 Version: v1 rev.1 110202

=Knowledge Requirements=
What your reading now is a beginners guide to L3P/L3PAO and POV-Ray. It assumes you have some knowledge of and experience with LDraw and one or more of its editors (such as MLCAD, LeoCAD, BrickDraw3D, etc) and creating models. What it wants to provide is a step by step guide of converting LDraw-models to POV-files and rendering them and what options you have when converting or rendering. What you won't find here is how to create models or parts.

Some chapters are on the practical side; you will do things after reading it. Other chapters are more theoretical, for example about cameras and lenses or color and light. Please read these chapters too. We try to make them as short and "light" as possible but they are important to understand some of the functions and options of L3P and POV-Ray.

=Chapter 1: Introduction=
So you have made some models; your own or existing Lego models. Now you want to have a nice picture of it, like the ones you see on Brickshelf or on other people's websites. However, your editor for LDraw can't so how do people do that? What you need is three programs and some additional files:

# L3P: a program that converts .DAT, .LDR and .MPD files to .POV (the native file format for POV-Ray)
# L3P AddOn (or L3PAO for short): a graphic interface for L3P
# POV-Ray: a freeware program to ray trace POV-files
# The LGEO-files for POV-Ray.

L3P is a DOS-program. It uses switches to call certain options. So for example, when you want your model with a certain camera position and background color you have to type the following in the DOS-prompt: L3P.exe tp-7745.dat tp-7745.pov -cc0,-96,-250 -ca45 -b0.000,0.000,0.251 -o You have to know (all) the options and their acronyms and when you make a typo, (and who doesn't now and then) you have to type it all over again. Or if you want a batch of models you have to retype the whole line over and over again.

This is why J. Boen created L3P AddOn, a graphic interface for L3P where you can turn on or off options in an easy way AND can save these options in "scenes" or snapshots.

POV-Ray is a freeware program to create and render computer generated pictures or animations. POV-Ray has no graphical interface in the sense that you see what you create; it has a source window where you type text commands and you can see what you created when you render the picture. Luckily, you don't have to learn all these commands; L3P creates a ready to render POV-file!

The LGEO-files for POV-Ray are files that POV-Ray uses to substitute some of the LDraw parts. The LGEO-files look better; cylinders are rounder, sloped bricks have that sandpaper structure, etc. They are also harder to render for POV-Ray; you will need lots of memory to use them.

However, before you can make a nice rendering of your model you have to download the above mentioned software. Best place to start is http://www.ldraw.org/download/win/. Go to the download section and click the appropriate links. We going to guide you with installing the programs but please read the installation guides of each program carefully!

=Chapter 2: Downloading and installing L3P, L3PAO and POV-Ray and LGEO=

'''LGEO-files''' We will start with the easiest: the LGEO-files.

# Go to http://www.el-lutzo.de/lego/lgeo.html
# Download the LGEO POV-Ray Library (Â±548kB)
# Place the Zip-file in the LDraw-directory an unzip it.
# That's it (for now)!

'''L3P''' L3P comes in two flavors: a 16-bit version and a 32-bit version. We recommend the latter because it is a bit faster, can handle long directory names (but no long filenames!) and can handle large LDraw files.

# Go to the [/modules.php?op=modload&name=Downloads&file=index Download] section
# Download L3P.zip.
# After downloading L3P.ZIP place the ZIP-file in the LDRAW-directory and unzip it. There are now two files in the LDRAW\L3P directory: L3P.EXE and L3P.TXT.
# DOS has to know where it can find L3P. Open a simple text editor like Notepad and open the AUTOEXEC.BAT or type "EDIT C:\AUTOEXEC.BAT" in the DOS-prompt.
# There probably will be a line starting with "set PATH=%PATH...". Place your cursor at the end of that. Now type the following sentence: ;C:\LDRAW\L3P (see below) and hit "Return" or "Enter".

[[Image:l3ppath.png]]

6. Now L3P has to know where it can find the LDraw parts and models. On the new line type:

<code> SET LDRAWDIR=C:\LDRAW (see below) </code> [[Image:l3pldrawdir.png]]

assuming the LDraw-directory is there. If you have placed it somewhere else please type the correct directory tree after C:\

7. L3P also needs to know where the LGEO-files are so in a new line under the SET LDRAWDIR line type:

<code> SET LGEODIR=c:\ldraw\lgeo </code>

Now every time you start up, DOS will read these commands and "know" where L3P is and where to find the LDraw parts and LGEO-files.

8. So, before going further with the L3PAO installation, please restart Windows.

'''L3PAO'''

# L3PAO.ZIP contains three files that should be unzipped in a temporally directory.
# Double click the SETUP.EXE and follow the instructions on screen. It is very simple. All you have to do is to point to the directory where L3PAO should be. By default, this is Program Files\L3PAO but the L3PAO manual recommends the same directory as where L3P is placed. So, hit the change directory-button and change the directory to c:\LDRAW\L3P.
# Now click the button with the computer icon on it. L3PAO will be installed. When finished it is ready to use, no restart needed.
# When you open L3PAO for the first time, it wants to know were it can find L3P (choose the LDRAW/L3P directory), Ledit (in the LDRAW directory) and LGEO-parts. Please point to the right directory.
# If you haven't installed POV-Ray and you open L3PAO, you will get a warning about that. Ignore it, close L3PAO and read on...

'''POV-Ray''' POV-Ray comes as POVWIN3.EXE. Download it and place it in a temporary directory. Now follow these 10 steps:

# Double click POVWIN3.EXE. You will be asked if you want to install POV-Ray: Click OK. The License Agreements opens now, read it and close it.
# A window opens asking if you agree with the agreement. Click Yes.
# The installer now asks where to place POV-Ray. By default, this is in the Program Files directory. Click OK if that is OK with you or choose an other directory.
# The installer will place an older version in a backup directory if you want (and have a older version). Choose Yes if you want to place the older version in a backup directory and No if you don't have a older version or don't want a backup of it.
# After copying the files in the right directories, the installer wants to know where to place the shortcut in the Start Menu. Click OK if you are happy with the default or choose an other place.
# The installer can place a shortcut on the desktop. Click Yes or No.
# By default, double clicking a POV-file will just open the file (click Yes). You can choose (but I don't recommend) to choose for double click is open and render. If you really really really want that, click No. By the way: as the window states: clicking with the right mouse button will open a menu where you can choose between Edit or Render.
# Next question: do you want a default directory for rendered files? It's up to you: choose Yes or No. Remember that if you choose No that POV-Ray will place the rendered file in the same directory as the POV-file, which can result in, files scattered all over your hard disk. (I chose Yes).
# A reminder
# Do you want a small demonstration? Click Yes.

Well that was easy wasn't it? You are ready to go now!

==Tips==

# Keep an eye on the various lugnet newsgroups for software updates: lugnet.cad.ray (for POV-Ray), lugnet.cad (for the others) or check ldraw.org.
# Lugnet.cad is also the place to post questions. However, before posting a question do a search to find out if no one posted the same question before you.

=Chapter 3: First conversion and rendering=
All the software is installed and you are ready to go! From the Start menu, choose L3P Add-On. The program starts and will show the following window:

[[Image:PIC0201.png]]

'''The L3PAO Interface''' Across the top you see three menu-items: File, Tools and Help. Below this are two text fields: the Model File (input) and POV-Ray Output File (output). Then there is the "switchboard" which is divided in 3 columns: camera, lights and other commands. Below these three columns is the "Generated Command Line"-box. This is where you can see (but not edit) the command line, which will be sent to L3P when you hit the "Run L3P" button bottom right. And lastly, the "Exit" button next to the "Run L3P" button, which will simply close the application.

The commands in the three "switchboard" columns will be covered in detail throughout this tutorial. Some of the more advanced topics are not covered. They will be discussed in other tutorials.

Alright, let's get started!

First, we need to load a .dat or .ldr model. To do this, use the "Model File" pull-down menu. Find a model file on your computer, by hitting the "..."-button to the right of the pop-up. You will be presented with a standard Open window where you can browse your computer. Throughout this tutorial, we will use the CAR.DAT, which is located in the LDRAW\MODELS-directory on your computer. This file is copied on your hard disk by the LDraw installer.

Because it is the first time you use L3PAO click the "..." button next to the "Model File"-pop-up. Browse to the LDRAW\MODELS-directory, click the CAR.DAT file and click "Open". The POV-file will be generated in the same directory as the DAT-file, unless you choose to specify a different location. For this example, we will not.

Uncheck "render upon complete" located near the bottom of L3PAO. Now click the "Run L3P" button. A DOS command window will appear and you will be able to watch the L3P commands run. However, if you have a fast computer, the box will disappear before you noticed it was there!

So now it is time to make your first rendering! Open the LDRAW\MODELS folder from your desktop and double click the CAR.POV file. The POV-Ray program will open, and will display the POV-Ray source code.

Before we get into any detail about POV-Ray, follow these instructions:

# On the top left-hand side, there is a pull-down menu with a series of dimensions. Choose 320 x 240, NO AA
# Hit the Start/Run button at the top of the interface to kick off your very first rendering
# POV-Ray will double check the code and prepare to render the car.pov file.
# After a few seconds (depending on your computer speed and the size of the file) a new window will open and line for line your first ray-traced (rendered) LEGO image appears!

=Chapter 4: A better first rendering=

[[Image:CAR.png]]

Yikes! It isn't what you hoped it would be, is it? It is a bit dark ...sort of a "car floating in space. Well you are right... the car is floating in space!

When making LDraw models, you usually don't need to define floors or backgrounds. Ldraw models look fine floating in space because of the flat, 2-Dimensional nature of the look. However, when you create a fully ray-traced model, you see something much closer to items in the real world that you see every day. When you see this "real" image, you expect it to also appear as though it is in a real environment. So let's fix this!

Open L3PAO again and choose the CAR.DAT again. If you look in the right side column, you will see two options: background (-b) and floor (-f) Click the checkbox to select background. The default background color in L3PAO is black,however, for our new rendering we will choose a different color. Click on the big black square, and a color picker window will open. Choose a nice shade of blue from the predefined colors. Click "OK".

Now select the floor option. By default, the floor is a light shade of gray, but we have some options to change that. There is a pull-down menu were you can choose between "g" (gray) or "c" (checkered, like a chess board).

In addition, there is a box with "Y" above it. This is the distance between the model and the floor. By default, this number is zero and this means the lowest part of your model will touch the floor. You can adjust this distance to make different effects. For instance, if you wanted to render an airplane or other flying object, you can lower the floor to make the model appear to be flying.

For our rendering select the "g" (gray) floor option, and leave the Y field blank. This will provide a rendering of the car sitting on a gray floor.Now, let's see what these new changes do for the rendering. Before we convert the file with these new options, let's change the "output name" of the file, to avoid overwriting our original car.pov file. In the "POV-Ray Output File" field at the top of the interface, change the name CAR.POV to CAR01.POV.

Now we are all set, so hit "Run L3P", and when it is done converting, switch back to POV-Ray, load the new CAR01.POV file, and Hit the "Start/Run" button to render. Note if you check off "Render upon complete" in L3PAO. L3PAO will open POV-Ray for you automatically and render the image using the last setting that POV-Ray had.

The result should look something like this:

[[Image:CAR01.png]]

Ah, that looks much better!

Because we have added the added floor, much more light will reflect back on the car, so the car looks much better. In addition, the car casts shadows on the floor so you get a lifelike image. The background will reflect light in the same manner as the floor, but since the background color is blue, the light being reflected is also somewhat blue. You can always change this by changing the background color to white.

Next stop: camera and lenses!

=Chapter 5: Camera and lenses (part 1)=

For a picture, you need three things: a model, light and a camera. Leave one out and the will be no picture (a Zen Buddhist would say you also need someone to watch the picture but more on that in the tutorial "Zen and the Art of LDraw).

With what we have rendered so far, you don't need to think about lights and camera placement. L3P very kindly places both of them for you at "fixed" locations. However, many times, you will want to change them to better suit your needs. So let's dive into camera placement and how L3P knows where to place it!

Before we start actually talking about the camera, we need to make sure that we understand the world the camera lives in, so to speak.

L3P uses the same coordinate system as LDraw. Remember those X, Y, Z axes from math class? Well, they're back! The X axis can be though of as the left to right plane, Y is the up to down plane, and Z is the forward to back plane. X and Z are parallel to the floor, while Y is perpendicular.

All three axes have both a positive and negative direction. Each axes changes from positive to negative at the center point of the globe. LDraw's coordinate system defines the axes in the following way:

+X (or simply X): Moving along the X axis to the right

-X: Moving along the X axis to the left

+ Y: Moving along the Y axis upwards

-Y: Moving along the Y axis downwards

+Z: Moving along the Z axis into the background

-Z: Moving along the Z axis into the foreground

If you take a look at the picture below, you will see all three axes, as well as a "globe" that is formed around them. This globe is the key to understanding how to move the camera and lights. L3P considers the model to be placed inside this globe, with the center point of the model's bounding box at the same place as the center point of the globe. (For reference, the Bounding Box is an imaginary box that the model fits in exactly. The top of the box lays on top of the highest point of the model, the bottom at the lowest point, and so on.)

[[Image:L3GLOBE2.png]]

Based on this globe system, the camera and lights can be easily placed by specifying Latitude, Longitude, and Radius (also known as polar coordinates).

Latitude is in the range from -90 degrees (south, along the positive y-axis) to 90 degrees (north, along the negative y-axis). Zero degrees is at the equator. Longitude is in the range from -180 to 180, where 0 degrees is along the negative z-axis. 90 degrees (east) is then along the positive x-axis and -90 degrees (west) is along the negative x-axis.

The basic LDraw views can be represented by these Latitude, Longitude pairs: Front=0,0 Right=0,-90 Left=0,90 Back=0,180 Over=90,0 Under=-90,0.

By now, you are probably asking, "This is great and all, but how do I move the camera around?" So let's dive into it!

The camera is placed at a certain distance from the model, which is called the "radius". By default, L3P calculates the radius so that the model fits very tightly in the rendering window. If you look at your last rendering, you see that the roof of the car is almost at the edge of the rendering window as is the bumper. If you want to specify a different camera globe position, L3P wants to know three things: the latitude (north or south position), longitude (east or west position) and radius (camera distance). As you can see in your last rendering, L3P calculates the radius so, that the model fits almost exactly in the picture. If you want you can move the camera away from the model so there is more space around the picture. The amount you give is a percentage.

By default L3P will place the camera as close as possible to the model. The viewing direction will be parallel to the direction given by the latitude (<la>) and longitude (<lo>). This won't necessarily be through the globe's center (also the model's center).

Think of the camera view towards the model as a funnel, with the point of funnel at the camera lens and the open end pointing towards the model. The funnel will be rotated so that its centerline is parallel to the direction vector defined by <la> and <lo> coordinates. L3P will move the funnel towards the model until it cannot come any closer.

The rendered image may look a bit distorted when the camera is moved that close, but this is to minimize the waste of empty rendered area. However, to get a nicer looking image (and a better look at the shadows) it may actually be better to have some amount of space around the model. To add this space, simply move the camera away from the model along the direction vector. If you specify a negative radius, e.g. -20, the camera will be moved 20% further away.

Yeah, yeah, you just want to do more rendering right? So let's do!

Open L3PAO, select CAR.DAT again and change the output name from to CAR02.POV Now go to the left column in the "switchboard" and check the -cg box. In the three input boxes, type in 0, 0, and -10 from left to right. Don't forget to add a floor and a background! Hit "Run L3P", and then render the new CAR02.POV file It will look like this:

[[Image:CAR02.png]]

Do you see what you did? You positioned the camera at the front of the model, and moved the camera back 10%. Fun, eh?

Now experiment for yourself on views. Try some different latitude and longitude settings to get a good feel of the polar coordinate system.

As an added feature of L3PAO, there is a "View Preset" pull-down menu that offers several standard views. These presets are already set to use the correct latitude, longitude, and radius to render some standard angles. You can use these as-is, or choose a preset and change the parameters a bit.

=Chapter 6: Camera and lenses (part 2)=

The radius (distance) of the camera from the model is calculated by L3P automatically for you. The camera radius depends on two things: the size of the model and the camera angle (or actually camera lens angle).

Camera angle, you ask? The lens of a camera has a certain angle, which determine what is visible and what is not. Basically how far to either side the camera can see. Human eyes have a viewing angle of 45 degrees, while the default camera angle in L3P is 67 degrees. Look at the picture below.

[[Image:camera.png]]

Lenses have their own characteristics: The normal lens (45Â°) will give a normal view. The telelens (<45Â°) will even the perspective: when using an extreme telelens you won't have perspective at all and all objects will have the same size; objects in the front and in the back of the picture. The wide lens (>45Â°) will distort the perspective: objects in the front look extremely big while objects in the back are very small, even in short distances.

Let's say the camera in the pictures above has a fixed distance towards a, b and c. The first camera has a standard lens. Not all the objects are visible (from this distance). The second lens is a tele-lens; only a small part of the picture is visible. Sports and wildlife photographers use this kind of lenses because you can get very "close" to an object from a distance (zoom in). The last lens is a wide- or fisheye lens; all the objects are visible. This is used in landscape and interior photography because you can get a lot on a picture without taking too much distance.

L3P uses the size of the model and the camera angle to calculate the radius. Lets say the two outer c's are the outer most part of a model. If you want to use a 45 degrees lens (as in the first camera), you have to move from the object. When using a 15 degrees lens you also have to move but a bit more extreme. In the last picture, you have to move to the model a bit.

Confused? Well let's try how it looks.

Open the CAR.DAT in L3PAO, add a floor and background and make 3 POV-files using Camera Globe Positions:

30,45,0 and Camera Angle 10 for CARCA010.POV

30,45,0 and Camera Angle 45 for CARCA045.POV

30,45,0 and Camera Angle 100 for CARCA100.POV

Open POV-Ray and render the pictures one by one.

The three pictures look like this:

[[Image:CARca010.png]]

This is the image rendered at a 10 degrees camera angle. You notice that the perspective lines are almost parallel. This is great when you want to render building steps of a model. The camera radius is roughly 1453 LDraw units (a 1 x 1 Brick is 24 LDraw units high).

[[Image:CARca045.png]]

This is the image rendered at 45 degrees camera angle. It has a much more life-like perspective. The camera radius is now just 334 LDraw units.

[[Image:CARca100.png]]

And last: the image rendered at a 100 degrees camera angle. You will notice that the picture is quite different: you can see the horizon now because the camera is closer and lower to the floor, which causes the car to look a bit odd. You can see how distorted the perspective is: the two red studs on right side of the bonnet are almost twice as large as the two studs on the left side. The camera is now only 194 LDraw units away.

If you look at the shadows on the floor, you will notice that these are different too. This is because, by default, L3P places 3 lights on fixed globe locations and at the same radius as the camera. Therefore, in the CARca045 image the lights are very far away and lit a large part of the floor while in the CARca100 image the camera, thus the lights are very close to the model, and a much smaller part of the floor is lit. Hence, the floor looks darker on the horizon.

=Chapter 7: Taking the camera out of the globe=

The default Camera Globe position is nice for pictures of the outside of a model. But what if you want a picture from within a model, almost as though you were inside the model looking out? You could change the radius to very small negative number so the camera will be in the model but the outcome will be very unpredictable. Therefore, it is better to take the camera from the globe so to speak and give it a fixed location. Instead of using the Camera Globe Position, we are going to use the Camera Coordinates in this chapter.

To get started, we need two coordinates: the camera coordinate and a "look at" point: the point where the camera will look at (or point at). These coordinates are LDraw coordinates so it is easy to determinate these.

Open the CAR.DAT in your LDraw editor (because I use and know MLCad best I will use that in this example but any other editor will do).

Place a 1 x 1 Brick inside the car above the chair at a height of a minifig's head. Make a note of the coordinates, which we will call -cc (it will be something like 0, -72, 10). Now place a 1 x 1 Brick in front of the car approximately at the same height as the one inside the car. You can place it a bit lower than the one inside, but don't over do it. Make a note of the coordinates, which we will call -cla (it will be something like 0, -56, -310). Delete both 1 x 1 Bricks and close the editor, without saving CAR.DAT.

Open L3PAO and open the CAR.DAT. Add a floor and background. Select the Camera Coordinates box (-cc), and fill in the coordinates in the three fields. Now select the Camera Look At box (-cla) and fill in the coordinates in the three fields. Change the output name to CARCC.DAT. Click "Run L3P" and open the .POV file.

After rendering, it will look like this.

[[Image:CARcc.png]]

Now you know what a mini-fig would see when driving a car! You can see the steering wheel and the reflection of the drivers seat in the window. You will have noticed that the time it took to render was considerable longer than the other pictures. This is because POV-Ray had to render through the windscreen and has to calculate all the refractions and reflections.

Now let's do this again, but from the outside to the inside of the car, like a car promotion brochure.

Open the CAR.DAT again in an LDraw editor. Select the steering wheel and make a note of its coordinates (0, -16, -30) , which will be the Look At coordinates (-cla).

Place a 1 x 1 Brick outside the car at the height of the roof and by the door. Make a note its coordinates (80, -80, 20), which will be the Camera Coordinates (-cc).

Now close the editor (again, don't save) and open L3PAO. Open the car, fill in the coordinates in the right fields. Choose 45 as camera angle (-ca). Select a floor and a blue background. Change the output file to CARCC2.POV.

Before you run L3P, we are going to save all these options in a "Scene".

Open the File menu and click "Save Scene". A standard Save as... window opens with L3P as directory (don't change that!). Now save the scene as CARCC2.xxx. If you were to close L3P (don't, but let's say) and want to use the same settings/options, all you have to do is open a DAT/LDR file, select "Open Scene" from the File menu and you are ready to go! No need to write everything down!

Hit "Run L3P", exit L3PAO and open CARCC2.POV in POV-Ray. Hit the "Run" button and wait...

[[Image:CARcc2a.png]]

The above image is the result. Because the rotation point of the Steering Wheel is at the bottom of the part, we are looking at the bottom of the car, or in other words: the center of the picture is not the steering wheel.

The good news is, is that we saved the options (phew!) and don't have to open the car in an editor to determine the coordinates.

Open L3PAO, load CAR.DAT and choose "Open Scene" from the File menu. Open the CARCC2.xxx. You see that all the parameters you used last time are back! Now all you have to do is to change the Y coordinate of the Look At point. Let's try two plate heights (or 32 LDraw units). So change the -16 in the second Look At box to -32.

Change the output name to CARCC3.POV, hit "Run L3P", exit L3PAO and open CARCC3.POV in POV-Ray. Hit the "Run" button and wait again while the image renders.

[[Image:CARcc2b.png]]

Yes, that is much better! The steering wheel is more in the center of the picture now.

Tips

# Start working out the Camera Globe position. Use the "car in the globe" picture to determine the position of the camera. Start with simple models first.
# Use the camera angle creatively but with care: use normal or tele-lenses (<50 degrees) for model presentation. Use a wider lens (>60 degrees) to add dynamics to a model or scene or to make it more "dramatic".
# Creation should be 90% Inspiration and 10% Transpiration. Look at real life pictures of objects similar to your model: how did other photographers take their picture? What was their point of view: low (or frog-view), normal viewing height or from a higher point (birds eye). Or think mini-fig height. Use a mini-fig to determine the camera coordinates.

[[Category:Tutorials]]

Conversion 101

2012-07-31T09:07:17Z

Timgould: /* Chapter 1: Introduction */

By: [mailto:info@digitalbricks.nl Jeroen de Haan] and [mailto:sink@countersinkdg.com Jake McKee] Posted: May 11, 2002 Version: v1 rev.1 110202

=Old page 1=
==Knowledge Requirements==
What your reading now is a beginners guide to L3P/L3PAO and POV-Ray. It assumes you have some knowledge of and experience with LDraw and one or more of its editors (such as MLCAD, LeoCAD, BrickDraw3D, etc) and creating models. What it wants to provide is a step by step guide of converting LDraw-models to POV-files and rendering them and what options you have when converting or rendering. What you won't find here is how to create models or parts.

Some chapters are on the practical side; you will do things after reading it. Other chapters are more theoretical, for example about cameras and lenses or color and light. Please read these chapters too. We try to make them as short and "light" as possible but they are important to understand some of the functions and options of L3P and POV-Ray.

==Chapter 1: Introduction==
So you have made some models; your own or existing Lego models. Now you want to have a nice picture of it, like the ones you see on Brickshelf or on other people's websites. However, your editor for LDraw can't so how do people do that? What you need is three programs and some additional files:

# L3P: a program that converts .DAT, .LDR and .MPD files to .POV (the native file format for POV-Ray)
# L3P AddOn (or L3PAO for short): a graphic interface for L3P
# POV-Ray: a freeware program to ray trace POV-files
# The LGEO-files for POV-Ray.

L3P is a DOS-program. It uses switches to call certain options. So for example, when you want your model with a certain camera position and background color you have to type the following in the DOS-prompt: L3P.exe tp-7745.dat tp-7745.pov -cc0,-96,-250 -ca45 -b0.000,0.000,0.251 -o You have to know (all) the options and their acronyms and when you make a typo, (and who doesn't now and then) you have to type it all over again. Or if you want a batch of models you have to retype the whole line over and over again.

This is why J. Boen created L3P AddOn, a graphic interface for L3P where you can turn on or off options in an easy way AND can save these options in "scenes" or snapshots.

POV-Ray is a freeware program to create and render computer generated pictures or animations. POV-Ray has no graphical interface in the sense that you see what you create; it has a source window where you type text commands and you can see what you created when you render the picture. Luckily, you don't have to learn all these commands; L3P creates a ready to render POV-file!

The LGEO-files for POV-Ray are files that POV-Ray uses to substitute some of the LDraw parts. The LGEO-files look better; cylinders are rounder, sloped bricks have that sandpaper structure, etc. They are also harder to render for POV-Ray; you will need lots of memory to use them.

However, before you can make a nice rendering of your model you have to download the above mentioned software. Best place to start is http://www.ldraw.org/download/win/. Go to the download section and click the appropriate links. We going to guide you with installing the programs but please read the installation guides of each program carefully!

=Chapter 2: Downloading and installing L3P, L3PAO and POV-Ray and LGEO=

'''LGEO-files''' We will start with the easiest: the LGEO-files.

# Go to http://www.el-lutzo.de/lego/lgeo.html
# Download the LGEO POV-Ray Library (Â±548kB)
# Place the Zip-file in the LDraw-directory an unzip it.
# That's it (for now)!

'''L3P''' L3P comes in two flavors: a 16-bit version and a 32-bit version. We recommend the latter because it is a bit faster, can handle long directory names (but no long filenames!) and can handle large LDraw files.

# Go to the [/modules.php?op=modload&name=Downloads&file=index Download] section
# Download L3P.zip.
# After downloading L3P.ZIP place the ZIP-file in the LDRAW-directory and unzip it. There are now two files in the LDRAW\L3P directory: L3P.EXE and L3P.TXT.
# DOS has to know where it can find L3P. Open a simple text editor like Notepad and open the AUTOEXEC.BAT or type "EDIT C:\AUTOEXEC.BAT" in the DOS-prompt.
# There probably will be a line starting with "set PATH=%PATH...". Place your cursor at the end of that. Now type the following sentence: ;C:\LDRAW\L3P (see below) and hit "Return" or "Enter".

[[Image:l3ppath.png]]

6. Now L3P has to know where it can find the LDraw parts and models. On the new line type:

<code> SET LDRAWDIR=C:\LDRAW (see below) </code> [[Image:l3pldrawdir.png]]

assuming the LDraw-directory is there. If you have placed it somewhere else please type the correct directory tree after C:\

7. L3P also needs to know where the LGEO-files are so in a new line under the SET LDRAWDIR line type:

<code> SET LGEODIR=c:\ldraw\lgeo </code>

Now every time you start up, DOS will read these commands and "know" where L3P is and where to find the LDraw parts and LGEO-files.

8. So, before going further with the L3PAO installation, please restart Windows.

'''L3PAO'''

# L3PAO.ZIP contains three files that should be unzipped in a temporally directory.
# Double click the SETUP.EXE and follow the instructions on screen. It is very simple. All you have to do is to point to the directory where L3PAO should be. By default, this is Program Files\L3PAO but the L3PAO manual recommends the same directory as where L3P is placed. So, hit the change directory-button and change the directory to c:\LDRAW\L3P.
# Now click the button with the computer icon on it. L3PAO will be installed. When finished it is ready to use, no restart needed.
# When you open L3PAO for the first time, it wants to know were it can find L3P (choose the LDRAW/L3P directory), Ledit (in the LDRAW directory) and LGEO-parts. Please point to the right directory.
# If you haven't installed POV-Ray and you open L3PAO, you will get a warning about that. Ignore it, close L3PAO and read on...

'''POV-Ray''' POV-Ray comes as POVWIN3.EXE. Download it and place it in a temporary directory. Now follow these 10 steps:

# Double click POVWIN3.EXE. You will be asked if you want to install POV-Ray: Click OK. The License Agreements opens now, read it and close it.
# A window opens asking if you agree with the agreement. Click Yes.
# The installer now asks where to place POV-Ray. By default, this is in the Program Files directory. Click OK if that is OK with you or choose an other directory.
# The installer will place an older version in a backup directory if you want (and have a older version). Choose Yes if you want to place the older version in a backup directory and No if you don't have a older version or don't want a backup of it.
# After copying the files in the right directories, the installer wants to know where to place the shortcut in the Start Menu. Click OK if you are happy with the default or choose an other place.
# The installer can place a shortcut on the desktop. Click Yes or No.
# By default, double clicking a POV-file will just open the file (click Yes). You can choose (but I don't recommend) to choose for double click is open and render. If you really really really want that, click No. By the way: as the window states: clicking with the right mouse button will open a menu where you can choose between Edit or Render.
# Next question: do you want a default directory for rendered files? It's up to you: choose Yes or No. Remember that if you choose No that POV-Ray will place the rendered file in the same directory as the POV-file, which can result in, files scattered all over your hard disk. (I chose Yes).
# A reminder
# Do you want a small demonstration? Click Yes.

Well that was easy wasn't it? You are ready to go now!

==Tips==

# Keep an eye on the various lugnet newsgroups for software updates: lugnet.cad.ray (for POV-Ray), lugnet.cad (for the others) or check ldraw.org.
# Lugnet.cad is also the place to post questions. However, before posting a question do a search to find out if no one posted the same question before you.

=Page 2=
==Chapter 3: First conversion and rendering==
All the software is installed and you are ready to go! From the Start menu, choose L3P Add-On. The program starts and will show the following window:

[[Image:PIC0201.png]]

'''The L3PAO Interface''' Across the top you see three menu-items: File, Tools and Help. Below this are two text fields: the Model File (input) and POV-Ray Output File (output). Then there is the "switchboard" which is divided in 3 columns: camera, lights and other commands. Below these three columns is the "Generated Command Line"-box. This is where you can see (but not edit) the command line, which will be sent to L3P when you hit the "Run L3P" button bottom right. And lastly, the "Exit" button next to the "Run L3P" button, which will simply close the application.

The commands in the three "switchboard" columns will be covered in detail throughout this tutorial. Some of the more advanced topics are not covered. They will be discussed in other tutorials.

Alright, let's get started!

First, we need to load a .dat or .ldr model. To do this, use the "Model File" pull-down menu. Find a model file on your computer, by hitting the "..."-button to the right of the pop-up. You will be presented with a standard Open window where you can browse your computer. Throughout this tutorial, we will use the CAR.DAT, which is located in the LDRAW\MODELS-directory on your computer. This file is copied on your hard disk by the LDraw installer.

Because it is the first time you use L3PAO click the "..." button next to the "Model File"-pop-up. Browse to the LDRAW\MODELS-directory, click the CAR.DAT file and click "Open". The POV-file will be generated in the same directory as the DAT-file, unless you choose to specify a different location. For this example, we will not.

Uncheck "render upon complete" located near the bottom of L3PAO. Now click the "Run L3P" button. A DOS command window will appear and you will be able to watch the L3P commands run. However, if you have a fast computer, the box will disappear before you noticed it was there!

So now it is time to make your first rendering! Open the LDRAW\MODELS folder from your desktop and double click the CAR.POV file. The POV-Ray program will open, and will display the POV-Ray source code.

Before we get into any detail about POV-Ray, follow these instructions:

# On the top left-hand side, there is a pull-down menu with a series of dimensions. Choose 320 x 240, NO AA
# Hit the Start/Run button at the top of the interface to kick off your very first rendering
# POV-Ray will double check the code and prepare to render the car.pov file.
# After a few seconds (depending on your computer speed and the size of the file) a new window will open and line for line your first ray-traced (rendered) LEGO image appears!

=Page 3=
==Chapter 4: A better first rendering==

[[Image:CAR.png]]

Yikes! It isn't what you hoped it would be, is it? It is a bit dark ...sort of a "car floating in space. Well you are right... the car is floating in space!

When making LDraw models, you usually don't need to define floors or backgrounds. Ldraw models look fine floating in space because of the flat, 2-Dimensional nature of the look. However, when you create a fully ray-traced model, you see something much closer to items in the real world that you see every day. When you see this "real" image, you expect it to also appear as though it is in a real environment. So let's fix this!

Open L3PAO again and choose the CAR.DAT again. If you look in the right side column, you will see two options: background (-b) and floor (-f) Click the checkbox to select background. The default background color in L3PAO is black,however, for our new rendering we will choose a different color. Click on the big black square, and a color picker window will open. Choose a nice shade of blue from the predefined colors. Click "OK".

Now select the floor option. By default, the floor is a light shade of gray, but we have some options to change that. There is a pull-down menu were you can choose between "g" (gray) or "c" (checkered, like a chess board).

In addition, there is a box with "Y" above it. This is the distance between the model and the floor. By default, this number is zero and this means the lowest part of your model will touch the floor. You can adjust this distance to make different effects. For instance, if you wanted to render an airplane or other flying object, you can lower the floor to make the model appear to be flying.

For our rendering select the "g" (gray) floor option, and leave the Y field blank. This will provide a rendering of the car sitting on a gray floor.Now, let's see what these new changes do for the rendering. Before we convert the file with these new options, let's change the "output name" of the file, to avoid overwriting our original car.pov file. In the "POV-Ray Output File" field at the top of the interface, change the name CAR.POV to CAR01.POV.

Now we are all set, so hit "Run L3P", and when it is done converting, switch back to POV-Ray, load the new CAR01.POV file, and Hit the "Start/Run" button to render. Note if you check off "Render upon complete" in L3PAO. L3PAO will open POV-Ray for you automatically and render the image using the last setting that POV-Ray had.

The result should look something like this:

[[Image:CAR01.png]]

Ah, that looks much better!

Because we have added the added floor, much more light will reflect back on the car, so the car looks much better. In addition, the car casts shadows on the floor so you get a lifelike image. The background will reflect light in the same manner as the floor, but since the background color is blue, the light being reflected is also somewhat blue. You can always change this by changing the background color to white.

Next stop: camera and lenses!

=Page 4=

==Chapter 5: Camera and lenses (part 1)==
For a picture, you need three things: a model, light and a camera. Leave one out and the will be no picture (a Zen Buddhist would say you also need someone to watch the picture but more on that in the tutorial "Zen and the Art of LDraw).

With what we have rendered so far, you don't need to think about lights and camera placement. L3P very kindly places both of them for you at "fixed" locations. However, many times, you will want to change them to better suit your needs. So let's dive into camera placement and how L3P knows where to place it!

Before we start actually talking about the camera, we need to make sure that we understand the world the camera lives in, so to speak.

L3P uses the same coordinate system as LDraw. Remember those X, Y, Z axes from math class? Well, they're back! The X axis can be though of as the left to right plane, Y is the up to down plane, and Z is the forward to back plane. X and Z are parallel to the floor, while Y is perpendicular.

All three axes have both a positive and negative direction. Each axes changes from positive to negative at the center point of the globe. LDraw's coordinate system defines the axes in the following way:

+X (or simply X): Moving along the X axis to the right

-X: Moving along the X axis to the left

+ Y: Moving along the Y axis upwards

-Y: Moving along the Y axis downwards

+Z: Moving along the Z axis into the background

-Z: Moving along the Z axis into the foreground

If you take a look at the picture below, you will see all three axes, as well as a "globe" that is formed around them. This globe is the key to understanding how to move the camera and lights. L3P considers the model to be placed inside this globe, with the center point of the model's bounding box at the same place as the center point of the globe. (For reference, the Bounding Box is an imaginary box that the model fits in exactly. The top of the box lays on top of the highest point of the model, the bottom at the lowest point, and so on.)

[[Image:L3GLOBE2.png]]

Based on this globe system, the camera and lights can be easily placed by specifying Latitude, Longitude, and Radius (also known as polar coordinates).

Latitude is in the range from -90 degrees (south, along the positive y-axis) to 90 degrees (north, along the negative y-axis). Zero degrees is at the equator. Longitude is in the range from -180 to 180, where 0 degrees is along the negative z-axis. 90 degrees (east) is then along the positive x-axis and -90 degrees (west) is along the negative x-axis.

The basic LDraw views can be represented by these Latitude, Longitude pairs: Front=0,0 Right=0,-90 Left=0,90 Back=0,180 Over=90,0 Under=-90,0.

By now, you are probably asking, "This is great and all, but how do I move the camera around?" So let's dive into it!

The camera is placed at a certain distance from the model, which is called the "radius". By default, L3P calculates the radius so that the model fits very tightly in the rendering window. If you look at your last rendering, you see that the roof of the car is almost at the edge of the rendering window as is the bumper. If you want to specify a different camera globe position, L3P wants to know three things: the latitude (north or south position), longitude (east or west position) and radius (camera distance). As you can see in your last rendering, L3P calculates the radius so, that the model fits almost exactly in the picture. If you want you can move the camera away from the model so there is more space around the picture. The amount you give is a percentage.

By default L3P will place the camera as close as possible to the model. The viewing direction will be parallel to the direction given by the latitude (<la>) and longitude (<lo>). This won't necessarily be through the globe's center (also the model's center).

Think of the camera view towards the model as a funnel, with the point of funnel at the camera lens and the open end pointing towards the model. The funnel will be rotated so that its centerline is parallel to the direction vector defined by <la> and <lo> coordinates. L3P will move the funnel towards the model until it cannot come any closer.

The rendered image may look a bit distorted when the camera is moved that close, but this is to minimize the waste of empty rendered area. However, to get a nicer looking image (and a better look at the shadows) it may actually be better to have some amount of space around the model. To add this space, simply move the camera away from the model along the direction vector. If you specify a negative radius, e.g. -20, the camera will be moved 20% further away.

Yeah, yeah, you just want to do more rendering right? So let's do!

Open L3PAO, select CAR.DAT again and change the output name from to CAR02.POV Now go to the left column in the "switchboard" and check the -cg box. In the three input boxes, type in 0, 0, and -10 from left to right. Don't forget to add a floor and a background! Hit "Run L3P", and then render the new CAR02.POV file It will look like this:

[[Image:CAR02.png]]

Do you see what you did? You positioned the camera at the front of the model, and moved the camera back 10%. Fun, eh?

Now experiment for yourself on views. Try some different latitude and longitude settings to get a good feel of the polar coordinate system.

As an added feature of L3PAO, there is a "View Preset" pull-down menu that offers several standard views. These presets are already set to use the correct latitude, longitude, and radius to render some standard angles. You can use these as-is, or choose a preset and change the parameters a bit.

=Page 5=
==Chapter 6: Camera and lenses (part 2)==

The radius (distance) of the camera from the model is calculated by L3P automatically for you. The camera radius depends on two things: the size of the model and the camera angle (or actually camera lens angle).

Camera angle, you ask? The lens of a camera has a certain angle, which determine what is visible and what is not. Basically how far to either side the camera can see. Human eyes have a viewing angle of 45 degrees, while the default camera angle in L3P is 67 degrees. Look at the picture below.

[[Image:camera.png]]

Lenses have their own characteristics: The normal lens (45Â°) will give a normal view. The telelens (<45Â°) will even the perspective: when using an extreme telelens you won't have perspective at all and all objects will have the same size; objects in the front and in the back of the picture. The wide lens (>45Â°) will distort the perspective: objects in the front look extremely big while objects in the back are very small, even in short distances.

Let's say the camera in the pictures above has a fixed distance towards a, b and c. The first camera has a standard lens. Not all the objects are visible (from this distance). The second lens is a tele-lens; only a small part of the picture is visible. Sports and wildlife photographers use this kind of lenses because you can get very "close" to an object from a distance (zoom in). The last lens is a wide- or fisheye lens; all the objects are visible. This is used in landscape and interior photography because you can get a lot on a picture without taking too much distance.

L3P uses the size of the model and the camera angle to calculate the radius. Lets say the two outer c's are the outer most part of a model. If you want to use a 45 degrees lens (as in the first camera), you have to move from the object. When using a 15 degrees lens you also have to move but a bit more extreme. In the last picture, you have to move to the model a bit.

Confused? Well let's try how it looks.

Open the CAR.DAT in L3PAO, add a floor and background and make 3 POV-files using Camera Globe Positions:

30,45,0 and Camera Angle 10 for CARCA010.POV

30,45,0 and Camera Angle 45 for CARCA045.POV

30,45,0 and Camera Angle 100 for CARCA100.POV

Open POV-Ray and render the pictures one by one.

The three pictures look like this:

[[Image:CARca010.png]]

This is the image rendered at a 10 degrees camera angle. You notice that the perspective lines are almost parallel. This is great when you want to render building steps of a model. The camera radius is roughly 1453 LDraw units (a 1 x 1 Brick is 24 LDraw units high).

[[Image:CARca045.png]]

This is the image rendered at 45 degrees camera angle. It has a much more life-like perspective. The camera radius is now just 334 LDraw units.

[[Image:CARca100.png]]

And last: the image rendered at a 100 degrees camera angle. You will notice that the picture is quite different: you can see the horizon now because the camera is closer and lower to the floor, which causes the car to look a bit odd. You can see how distorted the perspective is: the two red studs on right side of the bonnet are almost twice as large as the two studs on the left side. The camera is now only 194 LDraw units away.

If you look at the shadows on the floor, you will notice that these are different too. This is because, by default, L3P places 3 lights on fixed globe locations and at the same radius as the camera. Therefore, in the CARca045 image the lights are very far away and lit a large part of the floor while in the CARca100 image the camera, thus the lights are very close to the model, and a much smaller part of the floor is lit. Hence, the floor looks darker on the horizon.

=Page 6=
==Chapter 7: Taking the camera out of the globe==

The default Camera Globe position is nice for pictures of the outside of a model. But what if you want a picture from within a model, almost as though you were inside the model looking out? You could change the radius to very small negative number so the camera will be in the model but the outcome will be very unpredictable. Therefore, it is better to take the camera from the globe so to speak and give it a fixed location. Instead of using the Camera Globe Position, we are going to use the Camera Coordinates in this chapter.

To get started, we need two coordinates: the camera coordinate and a "look at" point: the point where the camera will look at (or point at). These coordinates are LDraw coordinates so it is easy to determinate these.

Open the CAR.DAT in your LDraw editor (because I use and know MLCad best I will use that in this example but any other editor will do).

Place a 1 x 1 Brick inside the car above the chair at a height of a minifig's head. Make a note of the coordinates, which we will call -cc (it will be something like 0, -72, 10). Now place a 1 x 1 Brick in front of the car approximately at the same height as the one inside the car. You can place it a bit lower than the one inside, but don't over do it. Make a note of the coordinates, which we will call -cla (it will be something like 0, -56, -310). Delete both 1 x 1 Bricks and close the editor, without saving CAR.DAT.

Open L3PAO and open the CAR.DAT. Add a floor and background. Select the Camera Coordinates box (-cc), and fill in the coordinates in the three fields. Now select the Camera Look At box (-cla) and fill in the coordinates in the three fields. Change the output name to CARCC.DAT. Click "Run L3P" and open the .POV file.

After rendering, it will look like this.

[[Image:CARcc.png]]

Now you know what a mini-fig would see when driving a car! You can see the steering wheel and the reflection of the drivers seat in the window. You will have noticed that the time it took to render was considerable longer than the other pictures. This is because POV-Ray had to render through the windscreen and has to calculate all the refractions and reflections.

Now let's do this again, but from the outside to the inside of the car, like a car promotion brochure.

Open the CAR.DAT again in an LDraw editor. Select the steering wheel and make a note of its coordinates (0, -16, -30) , which will be the Look At coordinates (-cla).

Place a 1 x 1 Brick outside the car at the height of the roof and by the door. Make a note its coordinates (80, -80, 20), which will be the Camera Coordinates (-cc).

Now close the editor (again, don't save) and open L3PAO. Open the car, fill in the coordinates in the right fields. Choose 45 as camera angle (-ca). Select a floor and a blue background. Change the output file to CARCC2.POV.

Before you run L3P, we are going to save all these options in a "Scene".

Open the File menu and click "Save Scene". A standard Save as... window opens with L3P as directory (don't change that!). Now save the scene as CARCC2.xxx. If you were to close L3P (don't, but let's say) and want to use the same settings/options, all you have to do is open a DAT/LDR file, select "Open Scene" from the File menu and you are ready to go! No need to write everything down!

Hit "Run L3P", exit L3PAO and open CARCC2.POV in POV-Ray. Hit the "Run" button and wait...

[[Image:CARcc2a.png]]

The above image is the result. Because the rotation point of the Steering Wheel is at the bottom of the part, we are looking at the bottom of the car, or in other words: the center of the picture is not the steering wheel.

The good news is, is that we saved the options (phew!) and don't have to open the car in an editor to determine the coordinates.

Open L3PAO, load CAR.DAT and choose "Open Scene" from the File menu. Open the CARCC2.xxx. You see that all the parameters you used last time are back! Now all you have to do is to change the Y coordinate of the Look At point. Let's try two plate heights (or 32 LDraw units). So change the -16 in the second Look At box to -32.

Change the output name to CARCC3.POV, hit "Run L3P", exit L3PAO and open CARCC3.POV in POV-Ray. Hit the "Run" button and wait again while the image renders.

[[Image:CARcc2b.png]]

Yes, that is much better! The steering wheel is more in the center of the picture now.

Tips

# Start working out the Camera Globe position. Use the "car in the globe" picture to determine the position of the camera. Start with simple models first.
# Use the camera angle creatively but with care: use normal or tele-lenses (<50 degrees) for model presentation. Use a wider lens (>60 degrees) to add dynamics to a model or scene or to make it more "dramatic".
# Creation should be 90% Inspiration and 10% Transpiration. Look at real life pictures of objects similar to your model: how did other photographers take their picture? What was their point of view: low (or frog-view), normal viewing height or from a higher point (birds eye). Or think mini-fig height. Use a mini-fig to determine the camera coordinates.

[[Category:Tutorials]]

Conversion 101

2012-07-31T09:05:53Z

Timgould: /* Page 6 */

By: [mailto:info@digitalbricks.nl Jeroen de Haan] and [mailto:sink@countersinkdg.com Jake McKee] Posted: May 11, 2002 Version: v1 rev.1 110202

=Old page 1=
==Knowledge Requirements==
What your reading now is a beginners guide to L3P/L3PAO and POV-Ray. It assumes you have some knowledge of and experience with LDraw and one or more of its editors (such as MLCAD, LeoCAD, BrickDraw3D, etc) and creating models. What it wants to provide is a step by step guide of converting LDraw-models to POV-files and rendering them and what options you have when converting or rendering. What you won't find here is how to create models or parts.

Some chapters are on the practical side; you will do things after reading it. Other chapters are more theoretical, for example about cameras and lenses or color and light. Please read these chapters too. We try to make them as short and "light" as possible but they are important to understand some of the functions and options of L3P and POV-Ray.

==Chapter 1: Introduction==
So you have made some models; your own or existing Lego models. Now you want to have a nice picture of it, like the ones you see on Brickshelf or on other people's websites. However, your editor for LDraw can't so how do people do that? What you need is three programs and some additional files:

# L3P: a program that converts .DAT, .LDR and .MPD files to .POV (the native file format for POV-Ray)
# L3P AddOn (or L3PAO for short): a graphic interface for L3P
# POV-Ray: a freeware program to ray trace POV-files
# The LGEO-files for POV-Ray.

L3P is a DOS-program. It uses switches to call certain options. So for example, when you want your model with a certain camera position and background color you have to type the following in the DOS-prompt: L3P.exe tp-7745.dat tp-7745.pov -cc0,-96,-250 -ca45 -b0.000,0.000,0.251 -o You have to know (all) the options and their acronyms and when you make a typo, (and who doesn't now and then) you have to type it all over again. Or if you want a batch of models you have to retype the whole line over and over again.

This is why J. Boen created L3P AddOn, a graphic interface for L3P where you can turn on or off options in an easy way AND can save these options in "scenes" or snapshots.

POV-Ray is a freeware program to create and render computer generated pictures or animations. POV-Ray has no graphical interface in the sense that you see what you create; it has a source window where you type text commands and you can see what you created when you render the picture. Luckily, you don't have to learn all these commands; L3P creates a ready to render POV-file!

The LGEO-files for POV-Ray are files that POV-Ray uses to substitute some of the LDraw parts. The LGEO-files look better; cylinders are rounder, sloped bricks have that sandpaper structure, etc. They are also harder to render for POV-Ray; you will need lots of memory to use them.

However, before you can make a nice rendering of your model you have to download the above mentioned software. Best place to start is http://www.ldraw.org/download/win/. Go to the download section and click the appropriate links. We going to guide you with installing the programs but please read the installation guides of each program carefully!

 Chapter 2: Downloading and installing L3P, L3PAO and POV-Ray and LGEO 

'''LGEO-files''' We will start with the easiest: the LGEO-files.

# Go to http://www.el-lutzo.de/lego/lgeo.html
# Download the LGEO POV-Ray Library (Â±548kB)
# Place the Zip-file in the LDraw-directory an unzip it.
# That's it (for now)!

'''L3P''' L3P comes in two flavors: a 16-bit version and a 32-bit version. We recommend the latter because it is a bit faster, can handle long directory names (but no long filenames!) and can handle large LDraw files.

# Go to the [/modules.php?op=modload&name=Downloads&file=index Download] section
# Download L3P.zip.
# After downloading L3P.ZIP place the ZIP-file in the LDRAW-directory and unzip it. There are now two files in the LDRAW\L3P directory: L3P.EXE and L3P.TXT.
# DOS has to know where it can find L3P. Open a simple text editor like Notepad and open the AUTOEXEC.BAT or type "EDIT C:\AUTOEXEC.BAT" in the DOS-prompt.
# There probably will be a line starting with "set PATH=%PATH...". Place your cursor at the end of that. Now type the following sentence: ;C:\LDRAW\L3P (see below) and hit "Return" or "Enter".

[[Image:l3ppath.png]]

6. Now L3P has to know where it can find the LDraw parts and models. On the new line type:

<code> SET LDRAWDIR=C:\LDRAW (see below) </code> [[Image:l3pldrawdir.png]]

assuming the LDraw-directory is there. If you have placed it somewhere else please type the correct directory tree after C:\

7. L3P also needs to know where the LGEO-files are so in a new line under the SET LDRAWDIR line type:

<code> SET LGEODIR=c:\ldraw\lgeo </code>

Now every time you start up, DOS will read these commands and "know" where L3P is and where to find the LDraw parts and LGEO-files.

8. So, before going further with the L3PAO installation, please restart Windows.

'''L3PAO'''

# L3PAO.ZIP contains three files that should be unzipped in a temporally directory.
# Double click the SETUP.EXE and follow the instructions on screen. It is very simple. All you have to do is to point to the directory where L3PAO should be. By default, this is Program Files\L3PAO but the L3PAO manual recommends the same directory as where L3P is placed. So, hit the change directory-button and change the directory to c:\LDRAW\L3P.
# Now click the button with the computer icon on it. L3PAO will be installed. When finished it is ready to use, no restart needed.
# When you open L3PAO for the first time, it wants to know were it can find L3P (choose the LDRAW/L3P directory), Ledit (in the LDRAW directory) and LGEO-parts. Please point to the right directory.
# If you haven't installed POV-Ray and you open L3PAO, you will get a warning about that. Ignore it, close L3PAO and read on...

'''POV-Ray''' POV-Ray comes as POVWIN3.EXE. Download it and place it in a temporary directory. Now follow these 10 steps:

# Double click POVWIN3.EXE. You will be asked if you want to install POV-Ray: Click OK. The License Agreements opens now, read it and close it.
# A window opens asking if you agree with the agreement. Click Yes.
# The installer now asks where to place POV-Ray. By default, this is in the Program Files directory. Click OK if that is OK with you or choose an other directory.
# The installer will place an older version in a backup directory if you want (and have a older version). Choose Yes if you want to place the older version in a backup directory and No if you don't have a older version or don't want a backup of it.
# After copying the files in the right directories, the installer wants to know where to place the shortcut in the Start Menu. Click OK if you are happy with the default or choose an other place.
# The installer can place a shortcut on the desktop. Click Yes or No.
# By default, double clicking a POV-file will just open the file (click Yes). You can choose (but I don't recommend) to choose for double click is open and render. If you really really really want that, click No. By the way: as the window states: clicking with the right mouse button will open a menu where you can choose between Edit or Render.
# Next question: do you want a default directory for rendered files? It's up to you: choose Yes or No. Remember that if you choose No that POV-Ray will place the rendered file in the same directory as the POV-file, which can result in, files scattered all over your hard disk. (I chose Yes).
# A reminder
# Do you want a small demonstration? Click Yes.

Well that was easy wasn't it? You are ready to go now!

==Tips==

# Keep an eye on the various lugnet newsgroups for software updates: lugnet.cad.ray (for POV-Ray), lugnet.cad (for the others) or check ldraw.org.
# Lugnet.cad is also the place to post questions. However, before posting a question do a search to find out if no one posted the same question before you.

=Page 2=
==Chapter 3: First conversion and rendering==
All the software is installed and you are ready to go! From the Start menu, choose L3P Add-On. The program starts and will show the following window:

[[Image:PIC0201.png]]

'''The L3PAO Interface''' Across the top you see three menu-items: File, Tools and Help. Below this are two text fields: the Model File (input) and POV-Ray Output File (output). Then there is the "switchboard" which is divided in 3 columns: camera, lights and other commands. Below these three columns is the "Generated Command Line"-box. This is where you can see (but not edit) the command line, which will be sent to L3P when you hit the "Run L3P" button bottom right. And lastly, the "Exit" button next to the "Run L3P" button, which will simply close the application.

The commands in the three "switchboard" columns will be covered in detail throughout this tutorial. Some of the more advanced topics are not covered. They will be discussed in other tutorials.

Alright, let's get started!

First, we need to load a .dat or .ldr model. To do this, use the "Model File" pull-down menu. Find a model file on your computer, by hitting the "..."-button to the right of the pop-up. You will be presented with a standard Open window where you can browse your computer. Throughout this tutorial, we will use the CAR.DAT, which is located in the LDRAW\MODELS-directory on your computer. This file is copied on your hard disk by the LDraw installer.

Because it is the first time you use L3PAO click the "..." button next to the "Model File"-pop-up. Browse to the LDRAW\MODELS-directory, click the CAR.DAT file and click "Open". The POV-file will be generated in the same directory as the DAT-file, unless you choose to specify a different location. For this example, we will not.

Uncheck "render upon complete" located near the bottom of L3PAO. Now click the "Run L3P" button. A DOS command window will appear and you will be able to watch the L3P commands run. However, if you have a fast computer, the box will disappear before you noticed it was there!

So now it is time to make your first rendering! Open the LDRAW\MODELS folder from your desktop and double click the CAR.POV file. The POV-Ray program will open, and will display the POV-Ray source code.

Before we get into any detail about POV-Ray, follow these instructions:

# On the top left-hand side, there is a pull-down menu with a series of dimensions. Choose 320 x 240, NO AA
# Hit the Start/Run button at the top of the interface to kick off your very first rendering
# POV-Ray will double check the code and prepare to render the car.pov file.
# After a few seconds (depending on your computer speed and the size of the file) a new window will open and line for line your first ray-traced (rendered) LEGO image appears!

=Page 3=
==Chapter 4: A better first rendering==

[[Image:CAR.png]]

Yikes! It isn't what you hoped it would be, is it? It is a bit dark ...sort of a "car floating in space. Well you are right... the car is floating in space!

When making LDraw models, you usually don't need to define floors or backgrounds. Ldraw models look fine floating in space because of the flat, 2-Dimensional nature of the look. However, when you create a fully ray-traced model, you see something much closer to items in the real world that you see every day. When you see this "real" image, you expect it to also appear as though it is in a real environment. So let's fix this!

Open L3PAO again and choose the CAR.DAT again. If you look in the right side column, you will see two options: background (-b) and floor (-f) Click the checkbox to select background. The default background color in L3PAO is black,however, for our new rendering we will choose a different color. Click on the big black square, and a color picker window will open. Choose a nice shade of blue from the predefined colors. Click "OK".

Now select the floor option. By default, the floor is a light shade of gray, but we have some options to change that. There is a pull-down menu were you can choose between "g" (gray) or "c" (checkered, like a chess board).

In addition, there is a box with "Y" above it. This is the distance between the model and the floor. By default, this number is zero and this means the lowest part of your model will touch the floor. You can adjust this distance to make different effects. For instance, if you wanted to render an airplane or other flying object, you can lower the floor to make the model appear to be flying.

For our rendering select the "g" (gray) floor option, and leave the Y field blank. This will provide a rendering of the car sitting on a gray floor.Now, let's see what these new changes do for the rendering. Before we convert the file with these new options, let's change the "output name" of the file, to avoid overwriting our original car.pov file. In the "POV-Ray Output File" field at the top of the interface, change the name CAR.POV to CAR01.POV.

Now we are all set, so hit "Run L3P", and when it is done converting, switch back to POV-Ray, load the new CAR01.POV file, and Hit the "Start/Run" button to render. Note if you check off "Render upon complete" in L3PAO. L3PAO will open POV-Ray for you automatically and render the image using the last setting that POV-Ray had.

The result should look something like this:

[[Image:CAR01.png]]

Ah, that looks much better!

Because we have added the added floor, much more light will reflect back on the car, so the car looks much better. In addition, the car casts shadows on the floor so you get a lifelike image. The background will reflect light in the same manner as the floor, but since the background color is blue, the light being reflected is also somewhat blue. You can always change this by changing the background color to white.

Next stop: camera and lenses!

=Page 4=

==Chapter 5: Camera and lenses (part 1)==
For a picture, you need three things: a model, light and a camera. Leave one out and the will be no picture (a Zen Buddhist would say you also need someone to watch the picture but more on that in the tutorial "Zen and the Art of LDraw).

With what we have rendered so far, you don't need to think about lights and camera placement. L3P very kindly places both of them for you at "fixed" locations. However, many times, you will want to change them to better suit your needs. So let's dive into camera placement and how L3P knows where to place it!

Before we start actually talking about the camera, we need to make sure that we understand the world the camera lives in, so to speak.

L3P uses the same coordinate system as LDraw. Remember those X, Y, Z axes from math class? Well, they're back! The X axis can be though of as the left to right plane, Y is the up to down plane, and Z is the forward to back plane. X and Z are parallel to the floor, while Y is perpendicular.

All three axes have both a positive and negative direction. Each axes changes from positive to negative at the center point of the globe. LDraw's coordinate system defines the axes in the following way:

+X (or simply X): Moving along the X axis to the right

-X: Moving along the X axis to the left

+ Y: Moving along the Y axis upwards

-Y: Moving along the Y axis downwards

+Z: Moving along the Z axis into the background

-Z: Moving along the Z axis into the foreground

If you take a look at the picture below, you will see all three axes, as well as a "globe" that is formed around them. This globe is the key to understanding how to move the camera and lights. L3P considers the model to be placed inside this globe, with the center point of the model's bounding box at the same place as the center point of the globe. (For reference, the Bounding Box is an imaginary box that the model fits in exactly. The top of the box lays on top of the highest point of the model, the bottom at the lowest point, and so on.)

[[Image:L3GLOBE2.png]]

Based on this globe system, the camera and lights can be easily placed by specifying Latitude, Longitude, and Radius (also known as polar coordinates).

Latitude is in the range from -90 degrees (south, along the positive y-axis) to 90 degrees (north, along the negative y-axis). Zero degrees is at the equator. Longitude is in the range from -180 to 180, where 0 degrees is along the negative z-axis. 90 degrees (east) is then along the positive x-axis and -90 degrees (west) is along the negative x-axis.

The basic LDraw views can be represented by these Latitude, Longitude pairs: Front=0,0 Right=0,-90 Left=0,90 Back=0,180 Over=90,0 Under=-90,0.

By now, you are probably asking, "This is great and all, but how do I move the camera around?" So let's dive into it!

The camera is placed at a certain distance from the model, which is called the "radius". By default, L3P calculates the radius so that the model fits very tightly in the rendering window. If you look at your last rendering, you see that the roof of the car is almost at the edge of the rendering window as is the bumper. If you want to specify a different camera globe position, L3P wants to know three things: the latitude (north or south position), longitude (east or west position) and radius (camera distance). As you can see in your last rendering, L3P calculates the radius so, that the model fits almost exactly in the picture. If you want you can move the camera away from the model so there is more space around the picture. The amount you give is a percentage.

By default L3P will place the camera as close as possible to the model. The viewing direction will be parallel to the direction given by the latitude (<la>) and longitude (<lo>). This won't necessarily be through the globe's center (also the model's center).

Think of the camera view towards the model as a funnel, with the point of funnel at the camera lens and the open end pointing towards the model. The funnel will be rotated so that its centerline is parallel to the direction vector defined by <la> and <lo> coordinates. L3P will move the funnel towards the model until it cannot come any closer.

The rendered image may look a bit distorted when the camera is moved that close, but this is to minimize the waste of empty rendered area. However, to get a nicer looking image (and a better look at the shadows) it may actually be better to have some amount of space around the model. To add this space, simply move the camera away from the model along the direction vector. If you specify a negative radius, e.g. -20, the camera will be moved 20% further away.

Yeah, yeah, you just want to do more rendering right? So let's do!

Open L3PAO, select CAR.DAT again and change the output name from to CAR02.POV Now go to the left column in the "switchboard" and check the -cg box. In the three input boxes, type in 0, 0, and -10 from left to right. Don't forget to add a floor and a background! Hit "Run L3P", and then render the new CAR02.POV file It will look like this:

[[Image:CAR02.png]]

Do you see what you did? You positioned the camera at the front of the model, and moved the camera back 10%. Fun, eh?

Now experiment for yourself on views. Try some different latitude and longitude settings to get a good feel of the polar coordinate system.

As an added feature of L3PAO, there is a "View Preset" pull-down menu that offers several standard views. These presets are already set to use the correct latitude, longitude, and radius to render some standard angles. You can use these as-is, or choose a preset and change the parameters a bit.

=Page 5=
==Chapter 6: Camera and lenses (part 2)==

The radius (distance) of the camera from the model is calculated by L3P automatically for you. The camera radius depends on two things: the size of the model and the camera angle (or actually camera lens angle).

Camera angle, you ask? The lens of a camera has a certain angle, which determine what is visible and what is not. Basically how far to either side the camera can see. Human eyes have a viewing angle of 45 degrees, while the default camera angle in L3P is 67 degrees. Look at the picture below.

[[Image:camera.png]]

Lenses have their own characteristics: The normal lens (45Â°) will give a normal view. The telelens (<45Â°) will even the perspective: when using an extreme telelens you won't have perspective at all and all objects will have the same size; objects in the front and in the back of the picture. The wide lens (>45Â°) will distort the perspective: objects in the front look extremely big while objects in the back are very small, even in short distances.

Let's say the camera in the pictures above has a fixed distance towards a, b and c. The first camera has a standard lens. Not all the objects are visible (from this distance). The second lens is a tele-lens; only a small part of the picture is visible. Sports and wildlife photographers use this kind of lenses because you can get very "close" to an object from a distance (zoom in). The last lens is a wide- or fisheye lens; all the objects are visible. This is used in landscape and interior photography because you can get a lot on a picture without taking too much distance.

L3P uses the size of the model and the camera angle to calculate the radius. Lets say the two outer c's are the outer most part of a model. If you want to use a 45 degrees lens (as in the first camera), you have to move from the object. When using a 15 degrees lens you also have to move but a bit more extreme. In the last picture, you have to move to the model a bit.

Confused? Well let's try how it looks.

Open the CAR.DAT in L3PAO, add a floor and background and make 3 POV-files using Camera Globe Positions:

30,45,0 and Camera Angle 10 for CARCA010.POV

30,45,0 and Camera Angle 45 for CARCA045.POV

30,45,0 and Camera Angle 100 for CARCA100.POV

Open POV-Ray and render the pictures one by one.

The three pictures look like this:

[[Image:CARca010.png]]

This is the image rendered at a 10 degrees camera angle. You notice that the perspective lines are almost parallel. This is great when you want to render building steps of a model. The camera radius is roughly 1453 LDraw units (a 1 x 1 Brick is 24 LDraw units high).

[[Image:CARca045.png]]

This is the image rendered at 45 degrees camera angle. It has a much more life-like perspective. The camera radius is now just 334 LDraw units.

[[Image:CARca100.png]]

And last: the image rendered at a 100 degrees camera angle. You will notice that the picture is quite different: you can see the horizon now because the camera is closer and lower to the floor, which causes the car to look a bit odd. You can see how distorted the perspective is: the two red studs on right side of the bonnet are almost twice as large as the two studs on the left side. The camera is now only 194 LDraw units away.

If you look at the shadows on the floor, you will notice that these are different too. This is because, by default, L3P places 3 lights on fixed globe locations and at the same radius as the camera. Therefore, in the CARca045 image the lights are very far away and lit a large part of the floor while in the CARca100 image the camera, thus the lights are very close to the model, and a much smaller part of the floor is lit. Hence, the floor looks darker on the horizon.

=Page 6=
==Chapter 7: Taking the camera out of the globe==

The default Camera Globe position is nice for pictures of the outside of a model. But what if you want a picture from within a model, almost as though you were inside the model looking out? You could change the radius to very small negative number so the camera will be in the model but the outcome will be very unpredictable. Therefore, it is better to take the camera from the globe so to speak and give it a fixed location. Instead of using the Camera Globe Position, we are going to use the Camera Coordinates in this chapter.

To get started, we need two coordinates: the camera coordinate and a "look at" point: the point where the camera will look at (or point at). These coordinates are LDraw coordinates so it is easy to determinate these.

Open the CAR.DAT in your LDraw editor (because I use and know MLCad best I will use that in this example but any other editor will do).

Place a 1 x 1 Brick inside the car above the chair at a height of a minifig's head. Make a note of the coordinates, which we will call -cc (it will be something like 0, -72, 10). Now place a 1 x 1 Brick in front of the car approximately at the same height as the one inside the car. You can place it a bit lower than the one inside, but don't over do it. Make a note of the coordinates, which we will call -cla (it will be something like 0, -56, -310). Delete both 1 x 1 Bricks and close the editor, without saving CAR.DAT.

Open L3PAO and open the CAR.DAT. Add a floor and background. Select the Camera Coordinates box (-cc), and fill in the coordinates in the three fields. Now select the Camera Look At box (-cla) and fill in the coordinates in the three fields. Change the output name to CARCC.DAT. Click "Run L3P" and open the .POV file.

After rendering, it will look like this.

[[Image:CARcc.png]]

Now you know what a mini-fig would see when driving a car! You can see the steering wheel and the reflection of the drivers seat in the window. You will have noticed that the time it took to render was considerable longer than the other pictures. This is because POV-Ray had to render through the windscreen and has to calculate all the refractions and reflections.

Now let's do this again, but from the outside to the inside of the car, like a car promotion brochure.

Open the CAR.DAT again in an LDraw editor. Select the steering wheel and make a note of its coordinates (0, -16, -30) , which will be the Look At coordinates (-cla).

Place a 1 x 1 Brick outside the car at the height of the roof and by the door. Make a note its coordinates (80, -80, 20), which will be the Camera Coordinates (-cc).

Now close the editor (again, don't save) and open L3PAO. Open the car, fill in the coordinates in the right fields. Choose 45 as camera angle (-ca). Select a floor and a blue background. Change the output file to CARCC2.POV.

Before you run L3P, we are going to save all these options in a "Scene".

Open the File menu and click "Save Scene". A standard Save as... window opens with L3P as directory (don't change that!). Now save the scene as CARCC2.xxx. If you were to close L3P (don't, but let's say) and want to use the same settings/options, all you have to do is open a DAT/LDR file, select "Open Scene" from the File menu and you are ready to go! No need to write everything down!

Hit "Run L3P", exit L3PAO and open CARCC2.POV in POV-Ray. Hit the "Run" button and wait...

[[Image:CARcc2a.png]]

The above image is the result. Because the rotation point of the Steering Wheel is at the bottom of the part, we are looking at the bottom of the car, or in other words: the center of the picture is not the steering wheel.

The good news is, is that we saved the options (phew!) and don't have to open the car in an editor to determine the coordinates.

Open L3PAO, load CAR.DAT and choose "Open Scene" from the File menu. Open the CARCC2.xxx. You see that all the parameters you used last time are back! Now all you have to do is to change the Y coordinate of the Look At point. Let's try two plate heights (or 32 LDraw units). So change the -16 in the second Look At box to -32.

Change the output name to CARCC3.POV, hit "Run L3P", exit L3PAO and open CARCC3.POV in POV-Ray. Hit the "Run" button and wait again while the image renders.

[[Image:CARcc2b.png]]

Yes, that is much better! The steering wheel is more in the center of the picture now.

Tips

# Start working out the Camera Globe position. Use the "car in the globe" picture to determine the position of the camera. Start with simple models first.
# Use the camera angle creatively but with care: use normal or tele-lenses (<50 degrees) for model presentation. Use a wider lens (>60 degrees) to add dynamics to a model or scene or to make it more "dramatic".
# Creation should be 90% Inspiration and 10% Transpiration. Look at real life pictures of objects similar to your model: how did other photographers take their picture? What was their point of view: low (or frog-view), normal viewing height or from a higher point (birds eye). Or think mini-fig height. Use a mini-fig to determine the camera coordinates.

[[Category:Tutorials]]

Conversion 101

2012-07-31T09:05:09Z

Timgould: /* Page 5 */

By: [mailto:info@digitalbricks.nl Jeroen de Haan] and [mailto:sink@countersinkdg.com Jake McKee] Posted: May 11, 2002 Version: v1 rev.1 110202

=Old page 1=
==Knowledge Requirements==
What your reading now is a beginners guide to L3P/L3PAO and POV-Ray. It assumes you have some knowledge of and experience with LDraw and one or more of its editors (such as MLCAD, LeoCAD, BrickDraw3D, etc) and creating models. What it wants to provide is a step by step guide of converting LDraw-models to POV-files and rendering them and what options you have when converting or rendering. What you won't find here is how to create models or parts.

Some chapters are on the practical side; you will do things after reading it. Other chapters are more theoretical, for example about cameras and lenses or color and light. Please read these chapters too. We try to make them as short and "light" as possible but they are important to understand some of the functions and options of L3P and POV-Ray.

==Chapter 1: Introduction==
So you have made some models; your own or existing Lego models. Now you want to have a nice picture of it, like the ones you see on Brickshelf or on other people's websites. However, your editor for LDraw can't so how do people do that? What you need is three programs and some additional files:

# L3P: a program that converts .DAT, .LDR and .MPD files to .POV (the native file format for POV-Ray)
# L3P AddOn (or L3PAO for short): a graphic interface for L3P
# POV-Ray: a freeware program to ray trace POV-files
# The LGEO-files for POV-Ray.

L3P is a DOS-program. It uses switches to call certain options. So for example, when you want your model with a certain camera position and background color you have to type the following in the DOS-prompt: L3P.exe tp-7745.dat tp-7745.pov -cc0,-96,-250 -ca45 -b0.000,0.000,0.251 -o You have to know (all) the options and their acronyms and when you make a typo, (and who doesn't now and then) you have to type it all over again. Or if you want a batch of models you have to retype the whole line over and over again.

This is why J. Boen created L3P AddOn, a graphic interface for L3P where you can turn on or off options in an easy way AND can save these options in "scenes" or snapshots.

POV-Ray is a freeware program to create and render computer generated pictures or animations. POV-Ray has no graphical interface in the sense that you see what you create; it has a source window where you type text commands and you can see what you created when you render the picture. Luckily, you don't have to learn all these commands; L3P creates a ready to render POV-file!

The LGEO-files for POV-Ray are files that POV-Ray uses to substitute some of the LDraw parts. The LGEO-files look better; cylinders are rounder, sloped bricks have that sandpaper structure, etc. They are also harder to render for POV-Ray; you will need lots of memory to use them.

However, before you can make a nice rendering of your model you have to download the above mentioned software. Best place to start is http://www.ldraw.org/download/win/. Go to the download section and click the appropriate links. We going to guide you with installing the programs but please read the installation guides of each program carefully!

 Chapter 2: Downloading and installing L3P, L3PAO and POV-Ray and LGEO 

'''LGEO-files''' We will start with the easiest: the LGEO-files.

# Go to http://www.el-lutzo.de/lego/lgeo.html
# Download the LGEO POV-Ray Library (Â±548kB)
# Place the Zip-file in the LDraw-directory an unzip it.
# That's it (for now)!

'''L3P''' L3P comes in two flavors: a 16-bit version and a 32-bit version. We recommend the latter because it is a bit faster, can handle long directory names (but no long filenames!) and can handle large LDraw files.

# Go to the [/modules.php?op=modload&name=Downloads&file=index Download] section
# Download L3P.zip.
# After downloading L3P.ZIP place the ZIP-file in the LDRAW-directory and unzip it. There are now two files in the LDRAW\L3P directory: L3P.EXE and L3P.TXT.
# DOS has to know where it can find L3P. Open a simple text editor like Notepad and open the AUTOEXEC.BAT or type "EDIT C:\AUTOEXEC.BAT" in the DOS-prompt.
# There probably will be a line starting with "set PATH=%PATH...". Place your cursor at the end of that. Now type the following sentence: ;C:\LDRAW\L3P (see below) and hit "Return" or "Enter".

[[Image:l3ppath.png]]

6. Now L3P has to know where it can find the LDraw parts and models. On the new line type:

<code> SET LDRAWDIR=C:\LDRAW (see below) </code> [[Image:l3pldrawdir.png]]

assuming the LDraw-directory is there. If you have placed it somewhere else please type the correct directory tree after C:\

7. L3P also needs to know where the LGEO-files are so in a new line under the SET LDRAWDIR line type:

<code> SET LGEODIR=c:\ldraw\lgeo </code>

Now every time you start up, DOS will read these commands and "know" where L3P is and where to find the LDraw parts and LGEO-files.

8. So, before going further with the L3PAO installation, please restart Windows.

'''L3PAO'''

# L3PAO.ZIP contains three files that should be unzipped in a temporally directory.
# Double click the SETUP.EXE and follow the instructions on screen. It is very simple. All you have to do is to point to the directory where L3PAO should be. By default, this is Program Files\L3PAO but the L3PAO manual recommends the same directory as where L3P is placed. So, hit the change directory-button and change the directory to c:\LDRAW\L3P.
# Now click the button with the computer icon on it. L3PAO will be installed. When finished it is ready to use, no restart needed.
# When you open L3PAO for the first time, it wants to know were it can find L3P (choose the LDRAW/L3P directory), Ledit (in the LDRAW directory) and LGEO-parts. Please point to the right directory.
# If you haven't installed POV-Ray and you open L3PAO, you will get a warning about that. Ignore it, close L3PAO and read on...

'''POV-Ray''' POV-Ray comes as POVWIN3.EXE. Download it and place it in a temporary directory. Now follow these 10 steps:

# Double click POVWIN3.EXE. You will be asked if you want to install POV-Ray: Click OK. The License Agreements opens now, read it and close it.
# A window opens asking if you agree with the agreement. Click Yes.
# The installer now asks where to place POV-Ray. By default, this is in the Program Files directory. Click OK if that is OK with you or choose an other directory.
# The installer will place an older version in a backup directory if you want (and have a older version). Choose Yes if you want to place the older version in a backup directory and No if you don't have a older version or don't want a backup of it.
# After copying the files in the right directories, the installer wants to know where to place the shortcut in the Start Menu. Click OK if you are happy with the default or choose an other place.
# The installer can place a shortcut on the desktop. Click Yes or No.
# By default, double clicking a POV-file will just open the file (click Yes). You can choose (but I don't recommend) to choose for double click is open and render. If you really really really want that, click No. By the way: as the window states: clicking with the right mouse button will open a menu where you can choose between Edit or Render.
# Next question: do you want a default directory for rendered files? It's up to you: choose Yes or No. Remember that if you choose No that POV-Ray will place the rendered file in the same directory as the POV-file, which can result in, files scattered all over your hard disk. (I chose Yes).
# A reminder
# Do you want a small demonstration? Click Yes.

Well that was easy wasn't it? You are ready to go now!

==Tips==

# Keep an eye on the various lugnet newsgroups for software updates: lugnet.cad.ray (for POV-Ray), lugnet.cad (for the others) or check ldraw.org.
# Lugnet.cad is also the place to post questions. However, before posting a question do a search to find out if no one posted the same question before you.

=Page 2=
==Chapter 3: First conversion and rendering==
All the software is installed and you are ready to go! From the Start menu, choose L3P Add-On. The program starts and will show the following window:

[[Image:PIC0201.png]]

'''The L3PAO Interface''' Across the top you see three menu-items: File, Tools and Help. Below this are two text fields: the Model File (input) and POV-Ray Output File (output). Then there is the "switchboard" which is divided in 3 columns: camera, lights and other commands. Below these three columns is the "Generated Command Line"-box. This is where you can see (but not edit) the command line, which will be sent to L3P when you hit the "Run L3P" button bottom right. And lastly, the "Exit" button next to the "Run L3P" button, which will simply close the application.

The commands in the three "switchboard" columns will be covered in detail throughout this tutorial. Some of the more advanced topics are not covered. They will be discussed in other tutorials.

Alright, let's get started!

First, we need to load a .dat or .ldr model. To do this, use the "Model File" pull-down menu. Find a model file on your computer, by hitting the "..."-button to the right of the pop-up. You will be presented with a standard Open window where you can browse your computer. Throughout this tutorial, we will use the CAR.DAT, which is located in the LDRAW\MODELS-directory on your computer. This file is copied on your hard disk by the LDraw installer.

Because it is the first time you use L3PAO click the "..." button next to the "Model File"-pop-up. Browse to the LDRAW\MODELS-directory, click the CAR.DAT file and click "Open". The POV-file will be generated in the same directory as the DAT-file, unless you choose to specify a different location. For this example, we will not.

Uncheck "render upon complete" located near the bottom of L3PAO. Now click the "Run L3P" button. A DOS command window will appear and you will be able to watch the L3P commands run. However, if you have a fast computer, the box will disappear before you noticed it was there!

So now it is time to make your first rendering! Open the LDRAW\MODELS folder from your desktop and double click the CAR.POV file. The POV-Ray program will open, and will display the POV-Ray source code.

Before we get into any detail about POV-Ray, follow these instructions:

# On the top left-hand side, there is a pull-down menu with a series of dimensions. Choose 320 x 240, NO AA
# Hit the Start/Run button at the top of the interface to kick off your very first rendering
# POV-Ray will double check the code and prepare to render the car.pov file.
# After a few seconds (depending on your computer speed and the size of the file) a new window will open and line for line your first ray-traced (rendered) LEGO image appears!

=Page 3=
==Chapter 4: A better first rendering==

[[Image:CAR.png]]

Yikes! It isn't what you hoped it would be, is it? It is a bit dark ...sort of a "car floating in space. Well you are right... the car is floating in space!

When making LDraw models, you usually don't need to define floors or backgrounds. Ldraw models look fine floating in space because of the flat, 2-Dimensional nature of the look. However, when you create a fully ray-traced model, you see something much closer to items in the real world that you see every day. When you see this "real" image, you expect it to also appear as though it is in a real environment. So let's fix this!

Open L3PAO again and choose the CAR.DAT again. If you look in the right side column, you will see two options: background (-b) and floor (-f) Click the checkbox to select background. The default background color in L3PAO is black,however, for our new rendering we will choose a different color. Click on the big black square, and a color picker window will open. Choose a nice shade of blue from the predefined colors. Click "OK".

Now select the floor option. By default, the floor is a light shade of gray, but we have some options to change that. There is a pull-down menu were you can choose between "g" (gray) or "c" (checkered, like a chess board).

In addition, there is a box with "Y" above it. This is the distance between the model and the floor. By default, this number is zero and this means the lowest part of your model will touch the floor. You can adjust this distance to make different effects. For instance, if you wanted to render an airplane or other flying object, you can lower the floor to make the model appear to be flying.

For our rendering select the "g" (gray) floor option, and leave the Y field blank. This will provide a rendering of the car sitting on a gray floor.Now, let's see what these new changes do for the rendering. Before we convert the file with these new options, let's change the "output name" of the file, to avoid overwriting our original car.pov file. In the "POV-Ray Output File" field at the top of the interface, change the name CAR.POV to CAR01.POV.

Now we are all set, so hit "Run L3P", and when it is done converting, switch back to POV-Ray, load the new CAR01.POV file, and Hit the "Start/Run" button to render. Note if you check off "Render upon complete" in L3PAO. L3PAO will open POV-Ray for you automatically and render the image using the last setting that POV-Ray had.

The result should look something like this:

[[Image:CAR01.png]]

Ah, that looks much better!

Because we have added the added floor, much more light will reflect back on the car, so the car looks much better. In addition, the car casts shadows on the floor so you get a lifelike image. The background will reflect light in the same manner as the floor, but since the background color is blue, the light being reflected is also somewhat blue. You can always change this by changing the background color to white.

Next stop: camera and lenses!

=Page 4=

==Chapter 5: Camera and lenses (part 1)==
For a picture, you need three things: a model, light and a camera. Leave one out and the will be no picture (a Zen Buddhist would say you also need someone to watch the picture but more on that in the tutorial "Zen and the Art of LDraw).

With what we have rendered so far, you don't need to think about lights and camera placement. L3P very kindly places both of them for you at "fixed" locations. However, many times, you will want to change them to better suit your needs. So let's dive into camera placement and how L3P knows where to place it!

Before we start actually talking about the camera, we need to make sure that we understand the world the camera lives in, so to speak.

L3P uses the same coordinate system as LDraw. Remember those X, Y, Z axes from math class? Well, they're back! The X axis can be though of as the left to right plane, Y is the up to down plane, and Z is the forward to back plane. X and Z are parallel to the floor, while Y is perpendicular.

All three axes have both a positive and negative direction. Each axes changes from positive to negative at the center point of the globe. LDraw's coordinate system defines the axes in the following way:

+X (or simply X): Moving along the X axis to the right

-X: Moving along the X axis to the left

+ Y: Moving along the Y axis upwards

-Y: Moving along the Y axis downwards

+Z: Moving along the Z axis into the background

-Z: Moving along the Z axis into the foreground

If you take a look at the picture below, you will see all three axes, as well as a "globe" that is formed around them. This globe is the key to understanding how to move the camera and lights. L3P considers the model to be placed inside this globe, with the center point of the model's bounding box at the same place as the center point of the globe. (For reference, the Bounding Box is an imaginary box that the model fits in exactly. The top of the box lays on top of the highest point of the model, the bottom at the lowest point, and so on.)

[[Image:L3GLOBE2.png]]

Based on this globe system, the camera and lights can be easily placed by specifying Latitude, Longitude, and Radius (also known as polar coordinates).

Latitude is in the range from -90 degrees (south, along the positive y-axis) to 90 degrees (north, along the negative y-axis). Zero degrees is at the equator. Longitude is in the range from -180 to 180, where 0 degrees is along the negative z-axis. 90 degrees (east) is then along the positive x-axis and -90 degrees (west) is along the negative x-axis.

The basic LDraw views can be represented by these Latitude, Longitude pairs: Front=0,0 Right=0,-90 Left=0,90 Back=0,180 Over=90,0 Under=-90,0.

By now, you are probably asking, "This is great and all, but how do I move the camera around?" So let's dive into it!

The camera is placed at a certain distance from the model, which is called the "radius". By default, L3P calculates the radius so that the model fits very tightly in the rendering window. If you look at your last rendering, you see that the roof of the car is almost at the edge of the rendering window as is the bumper. If you want to specify a different camera globe position, L3P wants to know three things: the latitude (north or south position), longitude (east or west position) and radius (camera distance). As you can see in your last rendering, L3P calculates the radius so, that the model fits almost exactly in the picture. If you want you can move the camera away from the model so there is more space around the picture. The amount you give is a percentage.

By default L3P will place the camera as close as possible to the model. The viewing direction will be parallel to the direction given by the latitude (<la>) and longitude (<lo>). This won't necessarily be through the globe's center (also the model's center).

Think of the camera view towards the model as a funnel, with the point of funnel at the camera lens and the open end pointing towards the model. The funnel will be rotated so that its centerline is parallel to the direction vector defined by <la> and <lo> coordinates. L3P will move the funnel towards the model until it cannot come any closer.

The rendered image may look a bit distorted when the camera is moved that close, but this is to minimize the waste of empty rendered area. However, to get a nicer looking image (and a better look at the shadows) it may actually be better to have some amount of space around the model. To add this space, simply move the camera away from the model along the direction vector. If you specify a negative radius, e.g. -20, the camera will be moved 20% further away.

Yeah, yeah, you just want to do more rendering right? So let's do!

Open L3PAO, select CAR.DAT again and change the output name from to CAR02.POV Now go to the left column in the "switchboard" and check the -cg box. In the three input boxes, type in 0, 0, and -10 from left to right. Don't forget to add a floor and a background! Hit "Run L3P", and then render the new CAR02.POV file It will look like this:

[[Image:CAR02.png]]

Do you see what you did? You positioned the camera at the front of the model, and moved the camera back 10%. Fun, eh?

Now experiment for yourself on views. Try some different latitude and longitude settings to get a good feel of the polar coordinate system.

As an added feature of L3PAO, there is a "View Preset" pull-down menu that offers several standard views. These presets are already set to use the correct latitude, longitude, and radius to render some standard angles. You can use these as-is, or choose a preset and change the parameters a bit.

=Page 5=
==Chapter 6: Camera and lenses (part 2)==

The radius (distance) of the camera from the model is calculated by L3P automatically for you. The camera radius depends on two things: the size of the model and the camera angle (or actually camera lens angle).

Camera angle, you ask? The lens of a camera has a certain angle, which determine what is visible and what is not. Basically how far to either side the camera can see. Human eyes have a viewing angle of 45 degrees, while the default camera angle in L3P is 67 degrees. Look at the picture below.

[[Image:camera.png]]

Lenses have their own characteristics: The normal lens (45Â°) will give a normal view. The telelens (<45Â°) will even the perspective: when using an extreme telelens you won't have perspective at all and all objects will have the same size; objects in the front and in the back of the picture. The wide lens (>45Â°) will distort the perspective: objects in the front look extremely big while objects in the back are very small, even in short distances.

Let's say the camera in the pictures above has a fixed distance towards a, b and c. The first camera has a standard lens. Not all the objects are visible (from this distance). The second lens is a tele-lens; only a small part of the picture is visible. Sports and wildlife photographers use this kind of lenses because you can get very "close" to an object from a distance (zoom in). The last lens is a wide- or fisheye lens; all the objects are visible. This is used in landscape and interior photography because you can get a lot on a picture without taking too much distance.

L3P uses the size of the model and the camera angle to calculate the radius. Lets say the two outer c's are the outer most part of a model. If you want to use a 45 degrees lens (as in the first camera), you have to move from the object. When using a 15 degrees lens you also have to move but a bit more extreme. In the last picture, you have to move to the model a bit.

Confused? Well let's try how it looks.

Open the CAR.DAT in L3PAO, add a floor and background and make 3 POV-files using Camera Globe Positions:

30,45,0 and Camera Angle 10 for CARCA010.POV

30,45,0 and Camera Angle 45 for CARCA045.POV

30,45,0 and Camera Angle 100 for CARCA100.POV

Open POV-Ray and render the pictures one by one.

The three pictures look like this:

[[Image:CARca010.png]]

This is the image rendered at a 10 degrees camera angle. You notice that the perspective lines are almost parallel. This is great when you want to render building steps of a model. The camera radius is roughly 1453 LDraw units (a 1 x 1 Brick is 24 LDraw units high).

[[Image:CARca045.png]]

This is the image rendered at 45 degrees camera angle. It has a much more life-like perspective. The camera radius is now just 334 LDraw units.

[[Image:CARca100.png]]

And last: the image rendered at a 100 degrees camera angle. You will notice that the picture is quite different: you can see the horizon now because the camera is closer and lower to the floor, which causes the car to look a bit odd. You can see how distorted the perspective is: the two red studs on right side of the bonnet are almost twice as large as the two studs on the left side. The camera is now only 194 LDraw units away.

If you look at the shadows on the floor, you will notice that these are different too. This is because, by default, L3P places 3 lights on fixed globe locations and at the same radius as the camera. Therefore, in the CARca045 image the lights are very far away and lit a large part of the floor while in the CARca100 image the camera, thus the lights are very close to the model, and a much smaller part of the floor is lit. Hence, the floor looks darker on the horizon.

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[[Category:Tutorials]]

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