http://racah.fiz.huji.ac.il/~eldadb/mic-react.html
Microscopic Simulation of Reaction-Diffusion Processes

They describe an entire class of common textures found in natural phenomena,
that seem to be missing from all of the POV work I have seen over the
years, with the exception of a few image maps such as those on G. Tran's
Zebras.

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Daniel Matthews wrote:

> http://racah.fiz.huji.ac.il/~eldadb/mic-react.html
> Microscopic Simulation of Reaction-Diffusion Processes
> 
> They describe an entire class of common textures found in natural
> phenomena, that seem to be missing from all of the POV work I have seen
> over the years, with the exception of a few image maps such as those on G.
> Tran's Zebras.

Ugh! That page is a little old (suffering from link rot).
Here is another,
http://cnls.lanl.gov/~aric/Simulations/Simulations.html

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In article <293### [at] 3-enet>, Daniel Matthews <dan#@3-e.net> 
wrote:

> > http://racah.fiz.huji.ac.il/~eldadb/mic-react.html
> > Microscopic Simulation of Reaction-Diffusion Processes
> > 
> > They describe an entire class of common textures found in natural
> > phenomena, that seem to be missing from all of the POV work I have seen
> > over the years, with the exception of a few image maps such as those on G.
> > Tran's Zebras.
> 
> Ugh! That page is a little old (suffering from link rot).
> Here is another,
> http://cnls.lanl.gov/~aric/Simulations/Simulations.html

These seem to be a bit different from the procedural patterns POV uses. 
They look like they have more in common with cellular automata...they 
are computed at a grid of points over a limited domain, such as a finite 
2D square. They are not ideal for POV patterns, though you could 
probably work them into the image_map feature (or possibly the density 
file feature for a 3D version). An external program would be better, you 
could adjust the pattern more easily and there is no real benefit to 
having it part of POV.

It would be interesting to see them "grown" on the surface of an object 
instead of a simple plane, but this would probably require tessellating 
the object, or otherwise coming up with points on the object and 
information about how they are connected by the surface, and I don't 
know how you could apply it to the original object.

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Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

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Christopher James Huff wrote:

> In article <293### [at] 3-enet>, Daniel Matthews <dan#@3-e.net>
> wrote:
> 
>> > http://racah.fiz.huji.ac.il/~eldadb/mic-react.html
>> > Microscopic Simulation of Reaction-Diffusion Processes
>> > 
>> > They describe an entire class of common textures found in natural
>> > phenomena, that seem to be missing from all of the POV work I have seen
>> > over the years, with the exception of a few image maps such as those on
>> > G. Tran's Zebras.
>> 
>> Ugh! That page is a little old (suffering from link rot).
>> Here is another,
>> http://cnls.lanl.gov/~aric/Simulations/Simulations.html
> 
> These seem to be a bit different from the procedural patterns POV uses.
> They look like they have more in common with cellular automata...they
> are computed at a grid of points over a limited domain, such as a finite
> 2D square. They are not ideal for POV patterns, though you could
> probably work them into the image_map feature (or possibly the density
> file feature for a 3D version). An external program would be better, you
> could adjust the pattern more easily and there is no real benefit to
> having it part of POV.
> 
> It would be interesting to see them "grown" on the surface of an object
> instead of a simple plane, but this would probably require tessellating
> the object, or otherwise coming up with points on the object and
> information about how they are connected by the surface, and I don't
> know how you could apply it to the original object.

Hmmm.. a density file could be generated with these methods
http://www.geocities.com/robisais/3dca.html

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Christopher James Huff wrote:

> They look like they have more in common with cellular automata
I like rule 101
http://kidojo.com/~yebb/cellauto/generate.cgi?rule=101&width=1024&height=768&pixelwidth=1&format=gif&random=1&showimage=true&name=/cellauto_101.gif

http://kidojo.com/~yebb/cellauto/generate.cgi

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In article <612### [at] 3-enet>,
 Daniel Matthews <dan#@3-e.net> wrote:

> Hmmm.. a density file could be generated with these methods
> http://www.geocities.com/robisais/3dca.html

And you could do the simulations themselves in POV, doing something like 
using a box or mesh triangle pair for each pixel. (I have done this, an 
extension to use an array as input would make it easier and more 
efficicent.)
POV-Script is very slow for heavy simulation though...you will quickly 
end up with parse times running far longer than the render time of the 
final scene-just for a single image map image. One reason I started 
working on Sapphire (originally CSDL, C-like Scene Description Language 
and later C-like Simulation Description Language).

For this kind of thing, languages like C/C++/Java have annoying compile 
and link stages that slow you down when you are constantly tweaking the 
algorithm. It's fine for a final fast version, but a pain while 
experimenting. Things like Ruby, Sapphire, even (gag) Python are better 
because you just write and run, like you do with POV. Also, Ruby has an 
interactive mode, where you work directly with objects, and Sapphire 
will have similar features for modifying a running program (I don't know 
if Python has these features).

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

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