I think that we have rather created the same thing. I also do some sample
weighting for hemisphere integration, with more samples near the surface
normal, as these contribute more. The only difference seems that my internal
rays test all objects for intersection instead of the container only. So,
during internal ray shooting towards the "other side", i might indeed hit the
"other side" or a "bone". Light integration is then performed in both cases. In
the former case, it works like yours. In the latter, the bone is completely
hidden from lights, thus it would contribute the desired "blackness" to the
effect with its ambient color setting.

Yes, this is dirty! No computation takes place for the light scattered on the
bone. But i pose the approximation hypothesis that the light reflected from a
bone is usually quite less than the one penetrating the surface.

For a more complete approach, one could address the problem from the light too,
not only ray-traced from the eye. It has been many years since i have read
Jensen's papers, but when i proposed photons, i had his methods for computing
shadows and caustics in my mind. I remember that he discriminates classes of
low and high density photons, the former for ambient lighting, the latter for
caustics etc which seems appropriate here and is implemented by POV's caustics.
So, an SSS object could become a photon target the usual way in POV terms.
Photons deposited on the object's "other side" depict translucent areas, so,
translucency can be inferred just from photon collection on the surface.
Photons deposited in internal objects depict "bone" lighting. These should be
visualized as normal caustics seen through the surface's matte refraction, in
other words, via shooting eye rays into the surface with directions and weights
just as you do today, but with the exception that you should not do shadow tests
anymore, as this has been taken care of by the photon deposition.

"clipka" <nomail@nomail> wrote:
> - For sample points moderately far away, I might re-use sample data collected
> earlier sufficiently close (similar to the radiosity sample cache); or, as you
> already mention, I might shoot photons at the object in advance, so I wouldn't
> have to bother about shadow tests and instead just "collect" the photons close
> enough to my sample points.
>

Yes, that is what i thought too.

Thank you for your great work!

-emmanuel

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