Hey Baggins do you ever study siggraph papers? Some very interesting ideas I think could be translated into VSS. The math is far beyond me but maybe you'll get a kick out of it and learn something new. I found this the other day and instantly thought of you...hehe :)

http://www1.cs.columbia.edu/CAVE/publications/

scroll down to 2005 Technical report pdf on "The Appearance of Human Skin"