MakeHuman and Povray's Subsurface Scattering

Greetings! Manuel asked me to find some imaging conditions that work well with the new SubSurface Scattering (SSS) effects possible with version 3.7 of the Persistence of Vision Raytracer. MakeHuman will contain a povray exporter. The purposes of these posts-- works in progress-- will be to demonstrate development on MakeHuman and to make a call for the best povray materials for realistic human skin. It has been noted that the subsurface scattering implementation in povray 3.7 is experimental and may change, but I decided to give it a whirl.

First, I imported the SSS parameters for conditions for "Skin1", "Skin2", and "Chicken" from Jensen, et al's paper, A Practical Model for Subsurface Light Transport. These are compared against my accidental choice of parameters and a simple view without SSS. First of all, I was surprised that the "Chicken1" parameters led to such dark meat! Secondly, I note that under these set of conditions, there were both an unseemly highlighting of mesh edges and "blue fingers". This merited further experimentation with the mm_per_unit parameter in the povray code.


In this set, I tried a range of values for mm_per_unit. As one can clearly see, there is no happy medium between highlighting of vertices (prominent in the center of pectoral muscle) and a lack of color in the fingers. There were only values of this parameter where both occurred. Some users may recognize the tile pattern from Christoph Lipka's subsurface.pov file, which comes with povray 3.7.




Here are the latest results. After further experimentation with the mm_per_unit value, I have settled on a value of around 8 and my version of diffuse + SSS. The image below unfortunately took 100 minutes to render. At this time I suppose it could be due to the fact that three models have SSS. I will continue experimentation to search for quality similar to this one with faster render time.



This is my code so far:
material {
texture {
pigment { color rgb 3*< 200/256,134/256,116/256 >}
finish {ambient 0 diffuse 0 specular 0.7882353/2
roughness 0.00286312
subsurface { 3* < 200/256,134/256,116/256>, < 0.013,>}
}
}
interior { ior 1.3 }
}


If you'd like to contribute your own material for fast, realistic skin, please chime in!