You have a notice of a lot my post here, in few days.
This is because I want use Povray to make a skin shader
for the MakeHuman project.

MakeHuman (GPL) is a python script to make parametric
humanoid in Blender. If you are curious, take a look here
(alpha vers., not very useful, but beta coming soon) :

http://www.kino3d.com/~MakeHuman/

My plans is to write a simple exporter Blender to Pov,
optimized and integrated in MakeHuman script.

Now the question.
Can Povray use a algorithm like this:

http://graphics.ucsd.edu/~henrik/papers/bssrdf/

or, more generally, exist a skin shader for Povray??

Thanks,

               Manuel

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On Thu, 22 May 2003 10:46:21 +0200, "Manuel" <man### [at] tinit> wrote:
> http://www.kino3d.com/~MakeHuman/

(offtopicly it is useless to open images in gallery in new not resizable window
when image is larger than user screen)

> http://graphics.ucsd.edu/~henrik/papers/bssrdf/
>
> or, more generally, exist a skin shader for Povray??

Perhaps POVMan can be helpful for you.
http://www.aetec.ee/fv/vkhomep.nsf/pages/povman2

ABX

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Manuel wrote:


> 
> My plans is to write a simple exporter Blender to Pov,
> optimized and integrated in MakeHuman script.

What about PovAnim? It works very well.

-- 
http://www.render-zone.com

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Manuel wrote:
> Now the question.
> Can Povray use a algorithm like this:
> 
> http://graphics.ucsd.edu/~henrik/papers/bssrdf/
> 
> or, more generally, exist a skin shader for Povray??
> 

As ABX said, one skin shader (Matt Pharr's) is in POVMan examples 
package. You probably need to tinker with it in order to get more 
realistic results than I got with my example.
Another skin shader, which probably could be used with POVMan, is 
Stephen H. Westin's at:
http://www.graphics.cornell.edu/~westin/lafortune/lafortune.html
It uses little bit newer technique (in terms of Siggraph publication 
year :-), but I haven't tried it.
I haven't found yet SL implementation for Jensen's algorithm and don't 
feel that I have enough expertise to implement it myself.
It should be noted, that POVMan does not support surface derivatives, so 
if you want to use available shaders (as Westin's), then you have to 
provide 'reasonable' derivative values yourself.

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Thanks to all, but perhaps I've used a
wrong expression to make my question.
My english is very poor, sorry.

My error is word "shader". I do not want
to use a Povray patch, like PovMan, but
I'm interested about the possibility to make
an advanced skin material in POV language.

About Povanim, it's too much complex
to insert it in the MakeHuman script: I'm
working on a "light" exporter...

Thanks again,

              Manuel

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> Now the question.
> Can Povray use a algorithm like this:
>
> http://graphics.ucsd.edu/~henrik/papers/bssrdf/
>
> or, more generally, exist a skin shader for Povray??
>
Well, this depend on what you want. Just in practice, subsurface scattering
(interior, volume effect...) cost some extra rendering time, everywhere. In
case of human head, it's hard to avoid artfacts, like interactions with
teeths or eyes, or overlapped surfaces (which is very hard to avoid with
animated lips, if you like your character to talk), etc.
I used skin shader from POVMan release, before few years, it was good,
somewhat slower than standard POV materials.

There is a good article of 'usable' human skin shading at
http://www.optidigit.com/stevens/shadetut.html . Human models on the rest of
this site looks very realistic. This is for Maya, but main principle is well
explained: some colors of skin depends by angle of incidence, light-shadow
or angle to camera. Say that ambient color and highlights are most
important. In this way, it's easy to get something very similar with
mentioned example, with rendering speed 'as usually'.
Almost all commercial 3d support this, even hardware accelerated rendering.
I founded one very similar shader for human skin, based on AOI, in nVidia
CG Toolkit.
In POV-Ray area, AOI (angle of incidence) is supported only by MLPOV,
http://pov.monde.free.fr/mael/mlpov083.html , as far as I know.

Anto

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> There is a good article of 'usable' human skin shading at
> http://www.optidigit.com/stevens/shadetut.html . Human models on the rest
of
> this site looks very realistic. This is for Maya, but main principle is
well
> explained: some colors of skin depends by angle of incidence, light-shadow
> or angle to camera.

Thx, I know it. Take a look to my experiment with simple phong renderer
in Blender:
http://www.elysiun.com/forum/viewtopic.php?t=8702&highlight=

Ok, I try...but Povray is not used for character??
This is the first time that a skin shader is requested?
Excuse the stupid question, I'm new to Pov, and I
think the POVpower is without limits... :-)

thanks,

   Manuel

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