After quite a bit of discussion about what features to tackle, and their requests to donate to the cause, I set up a chipin event for it. No sooner did I do that, I got a handful of donations, so it's definitely game on for me.
I still need to put up a formal proposal for what I'll be doing and how long I estimate each feature might take, but for now here's the high-level overview of what I'll be working on.
- Environment image importance sampling (lightprobes, and maybe more should be affected). Backgrounds in Cycles can produce a lot of noise in the rendered images, so this should help reduce it quite substantially for some scenes.
- Bidirectional path tracing integrator. This should help reduce noise in indoor and indirectly-lit scenes, but it's quite a bit of work (and difficult to get right).