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Git Commits -> Revision e716f10

January 20, 2017, 10:25 (GMT)
Cycles: Use correct light sampling PDF for MIS calculation with Branched Path Tracing

The light sampling functions calculate light sampling PDF for the case that the light has been randomly selected out of all lights.
However, since BPT handles lamps and meshlights separately, this isn't the case. So, to avoid a wrong result, the code just included the 0.5 factor in the throughput.

In theory, however, the correction should be made to the sampling probability, which needs to be doubled. Now, for the regular calculation, that's no real difference since the throughput is divided by the pdf.
However, it does matter for the MIS calculation - it's unbiased both ways, but including the factor in the PDF instead of the throughput should give slightly better results.

Reviewers: sergey, brecht, dingto, juicyfruit

Differential Revision: https://developer.blender.org/D2258

Commit Details:

Full Hash: e716f10ba91fd6a162867ef3cd5225d259bd87e5
Parent Commit: e04cc46
Committed By: Sergey Sharybin
Lines Changed: +15, -12

2 Modified Paths:

/intern/cycles/kernel/kernel_path_surface.h (+9, -6) (Diff)
/intern/cycles/kernel/kernel_path_volume.h (+6, -6) (Diff)
Tehnyt: Miika HämäläinenViimeksi päivitetty: 07.11.2014 14:18MiikaH:n Sivut a.k.a. MiikaHweb | 2003-2021