Okay so here is a new topic to talk about human skin. I am sure there will be some discussion around the subject so let's start with a few pictures:
Here is a pure glass shader I adjusted to mimic skin subsurface:
There is no bump or displacement, this is a high resolution model.
Here is a couple of examples with lower resolution models. I mixed the above subsurface shader with a default shader:
And here are the same in another lighting condition:
So it's possible to achieve the subsurface aspect of the skin.
The issue at the moment is how to mix it with texture. Currently it looks like mapping a color image on the object UVs doesn't work with the
volume color function. However it does work with the
volume density function. Could that be a bug?
Anyway, in the above examples, I used a glass shader only for the subsurface effect, with reflection and caustics turned off. I then merged it to a default shader taking care of the diffuse, reflections and bump. Because of the two shaders are merged in ADD, I am pretty sure this breaks energy conservation and it is not physically accurate. But with a bit of work and proper geometry/textures, this should be doable.
Speaking of models, one is the courtesy of Lee Perry Smith, which can be found on the
Arnold guide to skin shading. I found the other model
here
