VRAY SSS Problems


#1

Hi Guys,

                  I've made                       the transition from Maxwell to Vray a while ago.

Now I’m encountering some untypical behaviour for SSS materials in V-ray.
For a better understanding, here’s a scene I rendered with Maxwell:

The same scene rendered with V-ray.
I used SSS Raytraced (refractive) Material, as a base in a Vray blend material with one coating for the “S”.

Object 1: SSS with variable thickness.
In Maxwell the more thicker the object gets, the blurrier and less visible the checkerboard becomes.
In V-ray the checkerboard remains sharp as long as it is visible. Also the checkerboard is overbright.

Object 2: Objects inside a SSS Material (You can think of little black balls in a glass of milk).
In Maxwell the balls look as expected. In V-ray they look strange.

Object 3: Opaque layer over SSS Material (Partly painted translucent plastic).
In such cases there should be a blurred shadow from the opaque layer inside the volume.
In Maxwell this behavior is obvious.
In V-ray there is no such shadow, it looks as if the letter is done in post.

                  Here's a screenshot of the Vray SSS material:

I can imagine that I’m doing something wrong and hope you might have some ideas on this behavior in Vray.
Thanks a lot for your help!


#2

it might be better to ask such detailed stuff in the chaosgroup forum…


#3

Thanks, I’m gonna do that!


#4

But report back here if you find a solution!

I’ve had similar problems with SSS and VRay. My understanding is that in order to calculate SSS quickly, VRay takes certain shortcuts that cause these kinds of problems.