SSS journey coming to an end

This post marks the end in my various experiments and explorations to get a fairly plausible skin for Ara.

The result you see above is based on the 3 Layer SSS approach. Ben Simonds does a a very good explanation on this topic.

In the comments section of Ben’s post are some interesting links to papers giving quite a  good insight into this problematic area.

The basic setup as described in Ben’s post is here too, but after a lot of experimentation I expanded the nodes a bit:

  • I use an additional sss mask for blending a sss version of the subdermal sss layer with a non-sss one. This gave me better control for applying the sss effect.
  • I modified the specular term by simulating a type of fresnel specularity. In my opinion this made a huge difference in the skins appearance.

It also took quite some time to develop a workflow for texture painting. I did a basic material setup in blender 2.5x with the 3 layers as texture slots and using the same mode as in the original material setup. Using GLSL materials I could than texture paint relatively easy.

But due to the fact that the 3 layers are combined using the screen mixing mode it took some practise to find the right colors to use. To have at least a bit of a non-destructive workflow, I used various layers for the skin details.

Interestingly the biggest problem in the end was to apply the brow texture. Usually you have a texture map with just the brows painted on an alpha only map. As texture layer you just mix it with 100% on top of the other textures. With the multi material setup where all the layers are cumulative I did not find a way to do this easily.

The node setup right now demonstrates for me that this approach is working. On my todo list for the skin shader is:

  • convert all color operations to a linear workflow correct version (screen -> add, …)
  • clean up the huge amount of work done by all the extra texture layers by combining them into one or baking normal maps.

The image shown above was rendered at 75% of the final resolution ( 1920×1080) and was slightly over my limit of 3 min per frame ( 3:15). I hope to reduce the render time with some of the cleanups mentioned above, but the biggest part took the hair anyway (~2 min).

I have to confess, that I may have overdone it here in regard to realistic display. I have to render a shot to see if the animation doesn’t look too clumsy now, in which case I even might consider tuning down the skin shader.

And btw, if anyone is wondering, the lashes are still missing.

Author: loramel


Leave a Reply

Your email address will not be published. Required fields are marked *