Far end of shadow noise

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lacilaci
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Far end of shadow noise

Post by lacilaci » Wed May 29, 2019 8:57 am

This might be normal behavior but if there is an object currently in a far end of shadow of an object, that area won't get denoised. Not sure if noise samples are too far inbetween or there is a correlation but denoiser won't do anything with those areas unless they are very low in noise.

In my test example I needed over 2500 samples for the area to get properly denoised and it's still kinda not perfect.

10samples
10_samples.jpg
10samples denoised
10_samples_denoised.jpg
50samples
50_samples.jpg
50samples denoised
50_samples_denoised.jpg
500samples
500_samples.jpg
500samples denoised
500_samples_denoised.jpg
scene:
noise_denoise_shadow.blend
(980.46 KiB) Downloaded 15 times
Is this normal? Or maybe oidn related issue?

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Dade
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Re: Far end of shadow noise

Post by Dade » Wed May 29, 2019 10:07 am

That is quite strange, are you using "tiled denoising" ? It may be a bug introduced with that patch, I will check.
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lacilaci
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Re: Far end of shadow noise

Post by lacilaci » Wed May 29, 2019 10:11 am

nope, this is normal denoising. I haven't even seen tiled denoising in blender actually

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Dade
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Re: Far end of shadow noise

Post by Dade » Thu May 30, 2019 7:37 am

I can reproduce the problem but I can not see any error on our side.

I will upgrade the binaries to the latest Oidn version than, if the problem is still there, I will report behavior to Intel.
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lacilaci
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Re: Far end of shadow noise

Post by lacilaci » Thu May 30, 2019 10:14 am

Dade wrote:
Thu May 30, 2019 7:37 am
I can reproduce the problem but I can not see any error on our side.

I will upgrade the binaries to the latest Oidn version than, if the problem is still there, I will report behavior to Intel.
Good, by the way, this can also happen in a more complex environment.. It always kinda seems related to very soft shadow. I assumed that maybe there is some pattern that oidn recognizes in that part.

wasd
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Re: Far end of shadow noise

Post by wasd » Thu May 30, 2019 1:14 pm

lacilaci wrote:
Wed May 29, 2019 8:57 am
denoiser won't do anything with those areas unless they are very low in noise.
I've got similar behaviour in this scene download/file.php?id=4471.
It's Glossy Translucent mixed with Null, with homogeneous multiscattering volume.
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CodeHD
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Re: Far end of shadow noise

Post by CodeHD » Thu May 30, 2019 2:20 pm

I did expereince some issues as well (though not this one) when there were completely black background areas in my image.
Have you tried computing albedo and average shading normal AOVs as well? I had the feeling that helped the algorithm.

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B.Y.O.B.
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Re: Far end of shadow noise

Post by B.Y.O.B. » Thu May 30, 2019 2:28 pm

CodeHD wrote:
Thu May 30, 2019 2:20 pm
Have you tried computing albedo and average shading normal AOVs as well? I had the feeling that helped the algorithm.
They are always enabled in BlendLuxCore if the denoiser is used.
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CodeHD
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Re: Far end of shadow noise

Post by CodeHD » Thu May 30, 2019 2:40 pm

B.Y.O.B. wrote:
Thu May 30, 2019 2:28 pm
They are always enabled in BlendLuxCore if the denoiser is used.
Hmm ok, it seems I was just wrong with that feeling.

I just tried that scene I had in mind again (indeed no difference when including albedo + nromal aov), and it seems to depend also on where I focus in that case, with the result failing completely when my object is defocused (which unfortunately is the scientifically correct case for that instrument :D ):

focused case (works):
foc_render.png
foc_denoise.png
defocused case (doesn't work):
defoc_render.png
defoc_denoise.png

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Re: Far end of shadow noise

Post by kintuX » Thu May 30, 2019 4:17 pm

I think it's OIDN 'failing' to achieve human anticipations... did observed similar issues on occasions & also with NVidia's denoiser... more so, all over noticing critiques about this tech. Human adapted, tolerance raised...

And a reminder, during NVidias first AI filtering/denoising demo it was noted that this tools are meant for better, faster, more efficient previewing!!! not final HQ renders. ;)

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