Basic algorithm:
Estimate the pixel correspondences (motion vectors) to the previous frame where their local patches match the best using non-local means. Then history is combined with the current frame with a temporal low pass filter (exponential moving average & temporal bilaterial filtering). To better control the parameters, we use perception error DeltaE2000. Pixel difference larger than 10 dE is rejected for detail preserving.
How to enable:
Add `r.PathTracing.TemporalDenoiser 1` in MRQ console variables when path tracing denoising is enabled in postprocess volume.
#jira UE-136319
#rb chris.kulla
#preflight 62aa28dca40a4dc3a0412e2f
[CL 20675469 by Tiantian Xie in ue5-main branch]
