SSS question

[Micha_cg]

Hi,

for what are the options scatter coeff and Fwd/Bck coeff ? At Wouters tutorial and the official help page I can not find any info.

-Micha

[joe_b]

Re: SSS question

Translucent - turning this on will make the material translucent - being able to transport light below the material surface. Note that refraction must be enabled for this effect to be visible. The effect is also known as sub-surface scattering (SSS). Currently VRayMtl supports only single-bounce scattering.

Thickness - this limits the rays that will be traced below the surface. This is useful if you do not want or don't need to trace the whole sub-surface volume.

Scatter coefficient - the amount of scattering inside the object. 0.0 means rays will be scattered in all directions; 1.0 means a ray cannot change its direction inside the sub-surface volume.

Forward/backward coefficient - controls the direction of scattering for a ray. 0.0 means a ray can only go forward (away from the surface, inside the object); 0.5 means that a ray has an equal chance of going forward or backward; 1.0 means a ray will be scattered backward (towards the surface, to the outside of the object).

This quote is from http://www.spot3d.com (where the most recent V-Ray for Max docs are )

[Micha_cg]

SSS question

Thank you Joe, I have overseen this docu.

[Micha_cg]

SSS question

Hmm, the two coeff dosn't show any effect here. Also the IOR dosn't show any influence. Only Thickness, refraction color, diffuse color and glossiness show an effect.

Joe, I send you a test scene. Please try glossiness 0.7, 0.5 and 0.2. Some starnge looking effects. Also test the parameters without effect. Maybe, there is a bug.

But I don't want to forget to say, the few parameters allow some nice sss effects. I will post all settings at the user tutorial M later.

[joe_b]

SSS question

Ok I'll ask Vlado to take a look at this thread. The SSS implementation is not available for me to look at - so I can't say for sure what the differences are between our SSS and what is used in V-Ray for Max. I also noticed strange things with glossiness and the previous trouble scenes you sent me. I'm not sure if it is caused by something we're doing or a V-Ray issue.

[Micha_cg]

SSS question

Thanks Joe.