I'll tell you something else about the GI that surprised me.

Much of what I thought was SSS in human skin is actually multiple diffuse reflections between skin surfaces. For example, even without my VSS shader, I see slight additional redness between arms and body, between fingers and toes, and between chin and neck.

This is because the skin reflects pink light onto other areas of skin, so wherever they are close they appear more red, as well as darker because the ambience from the environment does not reach into there, particularly blue light from the sky.

So for human figures, I care a little less about SSS, since I was mistaken about where these effects were coming from. They are the result of diffuse inter-reflection, not sub-surface scattering.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)