On: Metropolis Algorithm and Bayesian posterior sampli...

[jcl]

Actually, the Renderman denoiser is based on work from Disney Research.

https://renderman.pixar.com/view/denoiser

PCA would be one way to do that. This recent paper suggests that they may be decomposing the samples mostly by path type, though:

https://www.disneyresearch.com/publication/pathspace-decompo...

[boulos → jcl]

He's referring to the older 2008 paper that did PCA, Statistical Acceleration for Animated Global Illumination: http://graphics.pixar.com/library/ShotRendering/paper.pdf