Depth-of-field + AO test
Using Structure Synth internal raytracer.
DOF is quite slow - you need to sample a lot of rays for each pixel. The same applies to ambient occlusion.
But I realized today, that when you combine these two techniques, you do not need a lot of AO samples - because the DOF automatically will sample new AO directions when applied. In fact, you can do nice renders using only one AO sample per object hits.
The image above was generated with 12*12 DOF samples per pixels, and 5 AO samples per object intersection. The rendering time was ~10 minutes, but a 1 minute render is only slightly more noisy.
The raytracer is now multi-threaded (this image was rendered in 8 threads on a i7 CPU).
The halo on the far tail seems a bit clipped, though. I believe this is due to the way I sample DOF rays on a finite circular disc. Perhaps I should choose gaussian distributed samples instead (corresponding to gaussian blur), but that doesn't seem physically correct? It could also interesting to sample on a polygon disc (a partly closed diapragm), to get some nicely shaped bokeh.