Re: [www-vrml] Fw: 3D renderings & Virtual tours (trees) (again)

[Miriam English <miriam@werple.net.au>]

Hi George,

George Birbilis wrote:
> I can't say existing solutions totally please me, but nevertheless, have 
> you found any useful links to papers/algorithms for existing methods, 
> e.g. in SIGRAPH etc.?
> SpeedTree looks promising but I suppose it's proprietary algorithms and 
> closed-source, isn't it?

L-Systems (Lindenmayer Systems) are one way to do it. Almost all free and open source. The first items on this list are more practical and immediately usable. The last 3 items on this list are more theoretical, but probably the most exciting.

Laurens Lapre's lparser. The old original version is a rather clunky DOS program. It generates l-system models directly in various formats including VRML and POV-Ray. The VRML models were waaaay too big, and I wrote a simple program some time back that resizes the model... or you could simply scale it down in a Transform.
But his new version directly outputs sensibly sized objects to VRML. Just drop an l-systems description file (the genetic code for the object) onto the program icon and it writes a VRML file. Unfortunately the wrl is in VRML1.0, but CosmoPlayer can display it, and Cortona can if you have installed their converter, and earlier versions of Contact (v4.4) will read it. (And you can download vrml1to2.exe from http://users.tpg.com.au/miriame/files/ )
The new lparser is very simple to use. You can also use it as a looping filter from DOS.
http://home.wanadoo.nl/laurens.lapre/
original lparser
http://home.wanadoo.nl/laurens.lapre/source.zip
new lparser
http://home.wanadoo.nl/laurens.lapre/lparser2.html

C.J. van der Mark's site has a nice set of pages with tutorials about l-systems
http://www.xs4all.nl/~cvdmark/

Blender code to create l-systems is at
http://www.geocities.com/blenderdungeon/lsystem/

Python code to generate l-systems is at
http://www.alcyone.com/pyos/lsystem/

A javascript VRML l-system generator is at
http://www.alpix.com/vrml/lsys.htm

The book "Late Night VRML 2.0 With Java" had some simple examples of l-systems in its pages as well as examples on the accompanying CD. The examples used java with VRML.

L-Breeder is a program (Linux, Mac, Win versions) that breeds generations of l-system creatures, allowing them to mutate at each generation, and producing very complex results in a surprisingly short number of cycles. It is now at
http://www.simonyi.ox.ac.uk/dawkins/software/yan/L-Breeder/

The original, landmark book "The Algorithmic Beauty of Plants" by P. Prusinkiewicz and A. Lindenmayer which inspired a lot of this stuff is now available on the net for free download [yay!!]
low quality fast download (3.7MB)
http://algorithmicbotany.org/papers/abop/abop.lowquality.pdf
or high quality big file (17MB)
http://algorithmicbotany.org/papers/abop/abop.pdf

The Algorithmic Botany is an amazing resource. You'll find more there than you ever thought existed on computationally modeling plants
http://algorithmicbotany.org/

There is some amazing work by Przemyslaw Prusinkiewicz on l-systems which have a lot more variables and so produce extraordinarily life-like plant behavior.
The fast access version, mostly plain text:
http://algorithmicbotany.org/vmm/
The deluxe version with lots of pretty pictures and animations:
http://algorithmicbotany.org/vmm-deluxe/

Hope this helps :)

	- Miriam

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