This is a full rewrite of the raytracing denoise pipeline. It uses the
same principle as before but now uses compute shaders for every stages
and a tile base approach. More aggressive filtering is needed since we
are moving towards having no prefiltered screen radiance buffer. Thus
we introduce a temporal denoise and a bilateral denoise stage to the
denoising. These are optionnal and can be disabled.
Note that this patch does not include any tracing part and only samples
the reflection probes. It is focused on denoising only. Tracing will
come in another PR.
The motivation for this is that having hardware raytracing support
means we can't prefilter the radiance in screen space so we have to
have better denoising. Also this means we can have better surface
appearance with support for other BxDF model than GGX. Also GGX support
is improved.
Technically, the new denoising fixes some implementation mistake the
old pipeline did. It separates all 3 stages (spatial, temporal,
bilateral) and use random sampling for all stages hoping to create
a noisy enough (but still stable) output so that the TAA soaks the
remaining noise. However that's not always the case. Depending on the
nature of the scene, the input can be very high frequency and might
create lots of flickering. That why another solution needs to be found
for the higher roughness material as denoising them becomes expensive
and low quality.
Pull Request: https://projects.blender.org/blender/blender/pulls/110117
Clément Foucault
17db856686