I've recently modeled a female torso, and am interested in applying a skin texture to it on the outside, as well as a subdermal fatty texture on the inside. Here are some screenshots to illustrate my goal:
Here is an overview of the female torso...
...and here it is with a bit of the reflected 'inside' of the skin. The yellow color indicates where I'd like the fatty tissue texture to be.
Currently what I have done is applied different lambert shaders to different faces of the model, but I wonder if I should go ahead and UV map it, and paint on the texture instead. The main problem is that I'd like the yellow parts to be bumpy, to reflect the texture of subdermal fat. Current I'm experimenting with displacement maps and mental ray's approximation editor, but they seem to be a bit weird around the face edges.
So I was wondering, what would you guys do? Would you UV map the whole thing, inside and out? Keep in mind that the skin does move around (the surgical instruments will pull and stretch the skin, so at certain points more 'yellow' faces are revealed).
Thank you in advance for your advice and time.