Hi there,
Been working on learning SSS lately, but am finding that there is a disappointing lack of learning material. My question is, how do you do SSS with more than 2 layers? I want to do a skin shader with 3 layers and I know that to add the SSS you plug RGB into the radius but then what?
Much appreciated
Hi Charlie A,
I am currently having the same issue. I am not able to create a real multi layer sss with cycles.
I am investigating (see for example my stackoverflow thread… empty :-): http://blender.stackexchange.com/questions/73581/real-multilayer-sss-in-cycles)
So basically, I came to the conclusions that with current sss shader, this doesn’t seem possible. I am trying to create it with translucency and absorption, but the is still not very conclusive for now…
If you had any idea by the way, or if it could give you some ideas…
good luck
here is the content of my thread on stackoverflow:
It seems to me that blender cycles is quite limited for doing a real multilayer sss…
What I want to achieve is something like that. Here is my bench, a shape with an increasing thickness
in renderman, you can define a multilayer sss like this:
and you obtain something like this
which is exactly what I want. To explain with a little graph, here the way I want my scatter to behave: 
But in blender cycles, it seems that you cannot achieve something better than that:
The reason for that is that you can tell the sss shader to be present from 0 thickness to x (via scale and radius), but there is no way to set presence from a to b where a > 0. The graph looks like something like that in blender cycles:
the deep layer is overlapping every layers…
very simple dummy node setup to summurize what is performed for any skin shader I found or tried to do (also this is a very bad setup here, no energy conservation): 
Is there a way in blender cycles to know the deepness of the scatering? Or am I thinking my shader the wrong way?
Thanks a lot! (and sorry for my average english…)
edit: digging… I have made a pretty nice step forward using absorption and translucency. It seems that sss is not absorbing the light rays, thus, make impossible the use of raylength, whereas translucency of course does. Here is the same bench:
with suzanne (right one has a quick white skull using solidify) 