Blender Git Commit Log

Git Commits -> Revision 07de832

Revision 07de832 by Lukas Stockner (master)
September 25, 2016, 21:16 (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: 07de832e22f5052d042605fdf3f8161a213c4f80
Parent Commit: 18b0738
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)
By: Miika HämäläinenLast update: Nov-07-2014 14:18MiikaHweb | 2003-2021