Best noise reduction approach

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nocivo
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Joined: Sun Jan 28, 2018 5:33 am
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Re: Best noise reduction approach

Post by nocivo »

I think that the problem is the anti-aliasing, that in bidir is not possible to use. I did some test with different pixel filter width, using the path tracing. By play with pixel filter width you can find the right setting according to the scene type. With default antialiasing setting the scene below failed to denoise, but with 3.0 or maybe 2.5 work well (at least in this situation)

path tracing with pixel filter width 3.0 and oidn apply
path tracing with pixel filter width 3.0 and oidn apply
path tracing with pixel filter width 1.5 (default value) and oidn apply
path tracing with pixel filter width 1.5 (default value) and oidn apply
bidir mlt pixel filter none and oidn apply
bidir mlt pixel filter none and oidn apply

As you can see with PF 3 there aren't problems (maybe a little blurred). In situation with tiny lines there is the moirè effect, and you have adjust the anti-aliasing according to the scene, to have the right result. Without the anti-aliasing also the albedo layer, have moirè effect and the denoiser fail (maybe because recognized the moire effect as noise, or something else, I don't know).

You disabled the PF when using Bidir because the Bidir noise pattern change when change the pixel filter width, and oidn does not recognize this noise pattern, that is very different from other Render engine.

My questions are:
  • Why don't change the antialiasing for bidir by align it to the path tracing type?(the noise pattern don't change when PF width change).
  • Or, Why don't work on improve the antialiasing of lux PT and BPT? that is the only thing that I think is not good in lux. For the other things I thinks that is very good.
Thanks
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