SSS Physical shader....

[max_lover]

Hi,
I am vray user (i think told already :D), I am trying to learn mental ray, so very noob at mental ray, I wanted to know that what are the functions of parameters in SSS physical shader,
Absorp. Coeff. and Scatter Coeff, I couldn't get that in mental ray manual, and I played with that..but failed to figure out. so need help :(
and same as in Submerge Plane Normal same 3 values :d
looking forward for tips and help thanks in advance
and oh yes :D lightmap in Fast SSS
so many question in single thread :D

[hot chip]

look here:

SSS Tips Overview
http://www.lamrug.org/resources/ssstips.html

Physical SSS Tips
http://www.lamrug.org/resources/physsstips.html

Skin SSS Tips
http://www.lamrug.org/resources/skintips.html

[max_lover]

thanks millions man, but are those RGB values ...3 value of coeffs.:rolleyes: ?noob again:D

[mustan9]

I wanted to know that what are the functions of parameters in SSS physical shader,
Absorp. Coeff. and Scatter Coeff, I couldn't get that in mental ray manual

I know what you mean. The SSS physical shader is one of the worse shaders in MR. You can tell some nerdy programmer created, and thought this was a really smart way to layout a shader.

Here is what I've been able to figure out.

The "absorption" and "scatter" parameters are not RGB values, but they directly effect the "color" of the sub surfaced scattered light. So I like to think of them as colored.

If you enter 1,0,0 you will not get a reddish subsurface color, but if you enter 0,1,1 you should. This is because the green and blue are absorbed. But! This is directly effected by the scale of the shader. So you may not get a reddish shattered color until you either adjust 0,1,1 to something like 0,2,2 or adjust the scale from 1.0 to 2.0. Understand what I mean?

Now, if you absorb all the color then there is nothing to scatter. So usually low absorption values are used. It's also possible to absorb the red color of light, but scatter mostly the blue.

I hope I helped pass some knowledge your way. I've only been playing with it for a while on a television spot that needs some milk done, but after about 8 hours I think I get most of how it works.

I am working on some MaxScript that will help make things easier, and I'll post them on my website.

[max_lover]

thanks man, really ..I am glad and happy :D, at least some strange parameters clear in my tiny mind :D, thanks again