photon mapping with the cornell box
October 10th, 2006 by BramzSummer is over (already 20 days since September 21), and as promised, we’re back with some more LiAR stuff =)
I’ve been busy with a few things, the main one being the photon mapper. It’s not completed yet. Currently we only have a global photon map and a gather step with a full radiance estimate. On the agenda are precomputed radiance estimates, importance driven photon shooting, caustic photon maps, …
The photon mapper does not use the traditional diffuse/specular/absorption Russian roulette of Jensen, but rather a full BSDF approach as described by Pharr. This required a complete refactoring of the shaders, which was the other big thing I was working on.
As you could read in an earlier post, I was not so happy with my material implementation. The shaders didn’t match well with things like photon mapping, so I completely ditched the shader approach for a BSDF one. I was a bit worried about having to evaluate expensive textures for each BSDF call, so I had to find a way to buffer them. The solution I’ve choosen is to compute many values in one call by some kind of iterator approach.
I guess that’s it for today. But of course, there’s still some render to show. OK, it’s only a dull cornell box, but it allows me to check my results more easily because I know what to expect. Overall, it looks good, but you might notice some problems at the edges of the wall. Apparently, the final gather doesn’t work so well over there.
