I experimented with fastscatter a lot and it just does not produce the kind of terminator that is correct. Also it doesn't work without depth-mapped shadows and I'm never going back to those.

I also experimented with refract a couple years ago. Nothing there seems reasonable.

Imagine a hard-edged shadow falls on a box. The edges should blur, allowing some of the nearby light outside the shadow to increase the luminance inside the shadow on the same surface. Refraction cannot possibly be made to help there, since the refracted ray cannot travel sideways and sample the surface nearby. It can only go through and sample the other side of the figure. That isn't going to be helpful. For example, refraction rays traced from the nose would travel through the nose. Some would hit the back of the head - of what use is that information? We want information about other parts of the nose nearby, not the other side of the head.

---

Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)