Cycles: restore Christensen-Burley SSS
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Authored by Brecht Van Lommel (brecht) on Oct 8 2021, 9:10 PM.

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Reviewers

Sergey Sharybin (sergey)
William Leeson (leesonw)

Commits

rC67c9207d6f10: Restore christensen-burley sss
rB73a05ff9e83a: Cycles: restore Christensen-Burley SSS

Summary

There is not enough time before the release to improve Random Walk to handle
all cases this was used for, so restore it for now.

Since there is no more path splitting in cycles-x, this can increase noise in
non-flat areas for the sample number of samples, though fewer rays will be traced
also. This is fundamentally a trade-off we made in the new design and why Random
Walk is a better fit.

This patch does not work by itself, it must be combined with the follow up patch
regarding handling of retro-reflection in the Principled BSDF.

I still need to benchmark the impact of this change.

Diff Detail

Repository: rB Blender

Event Timeline

Brecht Van Lommel (brecht) requested review of this revision.Oct 8 2021, 9:10 PM

Brecht Van Lommel (brecht) created this revision.

Harbormaster completed remote builds in B17669: Diff 43068.Oct 8 2021, 9:10 PM

Brecht Van Lommel (brecht) added a child revision: D12801: Cycles: improve SSS Fresnel and retro-reflection in Principled BSDF.Oct 8 2021, 9:11 PM

Alaska (Alaska) awarded a token.Oct 8 2021, 10:30 PM

Pinus awarded a token.Oct 9 2021, 1:17 AM

kursad k (kursadk) awarded a token.Oct 9 2021, 3:28 AM

Mikhail Matrosov (ktdfly) awarded a token.Oct 11 2021, 9:44 AM

Wo!262 (wo262) awarded a token.Oct 11 2021, 9:54 AM

Something we also talked to Brecht about. A bit annoying, is better to go this route for 3.0.
The benchmarks and memory usage seems to be roughly the same (compared this patch with with the current master). But always worth double-checking on a newer-gen card!

This revision is now accepted and ready to land.Oct 11 2021, 10:59 AM

I ran CPU and GPU benchmarks and found no significant difference, so this should not impact performance for Random Walk or other features.

Closed by commit rB73a05ff9e83a: Cycles: restore Christensen-Burley SSS (authored by Brecht Van Lommel (brecht)). · Explain WhyOct 11 2021, 6:27 PM

This revision was automatically updated to reflect the committed changes.

Brecht Van Lommel (brecht) added a commit: rB73a05ff9e83a: Cycles: restore Christensen-Burley SSS.

Brecht Van Lommel (brecht) mentioned this in rBL62719: Tests: update for restoring Christensen-Burley SSS.

Brecht Van Lommel (brecht) added a commit: rC67c9207d6f10: Restore christensen-burley sss.Jan 27 2022, 11:29 PM