Denoiser CPU and GPU different results.

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FarbigeWelt
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Re: Denoiser CPU and GPU different results.

Post by FarbigeWelt » Sat Nov 10, 2018 10:33 pm

Hi Dez!

Have you tried to compare same looking. not denoised images, by subtracting then, ouput file should have at least 16 bit. There should be a node for substract it in blender composer, maybe increase of exposure is required to see difference. If difference is good visible without exposure adjustment then you know the source for different denoiser results, hidden brightness if looking at 8 bit images.

CPU and GPU path show different results in many cases, e.g. light colors after passng through rough glass.
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B.Y.O.B.
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Re: Denoiser CPU and GPU different results.

Post by B.Y.O.B. » Sat Nov 10, 2018 10:56 pm

FarbigeWelt wrote:
Sat Nov 10, 2018 10:33 pm
CPU and GPU path show different results in many cases, e.g. light colors after passng through rough glass.
It would be great if you could report these cases, because they usually are bugs.
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FarbigeWelt
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Re: Denoiser CPU and GPU different results.

Post by FarbigeWelt » Mon Nov 12, 2018 12:33 pm

B.Y.O.B. wrote:
Sat Nov 10, 2018 10:56 pm
FarbigeWelt wrote:
Sat Nov 10, 2018 10:33 pm
CPU and GPU path show different results in many cases, e.g. light colors after passng through rough glass.
It would be great if you could report these cases, because they usually are bugs.
Well, I did a while ago:

„Green light of LED bar (white point lamps, irregular data color input for glass' transparancy) is not visible with GPU path and only slightly visible with CPU Path but is overall visible with CPU BiDir.“
4469B671-4082-4237-9AD9-280BA550E9A3.jpeg
GPU path, CPU path with different green tone of LED
But could be fixed, I‘ll have to render the scene with beta 1 again.
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Re: Denoiser CPU and GPU different results.

Post by B.Y.O.B. » Mon Nov 12, 2018 1:10 pm

It would be best to have a much more simple scene, just the elements that cause the difference.
You can help us developers a lot by making test scenes as simple as possible, while still reproducing the problem.
And then it's best to open a github issue, posts in a long thread get lost very easily, while github issues can be tagged and searched much better.
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Dade
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Re: Denoiser CPU and GPU different results.

Post by Dade » Mon Nov 12, 2018 2:00 pm

FarbigeWelt wrote:
Mon Nov 12, 2018 12:33 pm
„Green light of LED bar (white point lamps, irregular data color input for glass' transparancy) is not visible with GPU path and only slightly visible with CPU Path but is overall visible with CPU BiDir.“
As I have explained answering to that post: Path can not render lights beyond specular surfaces while BiDir can.
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FarbigeWelt
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Re: Denoiser CPU and GPU different results.

Post by FarbigeWelt » Mon Nov 12, 2018 2:59 pm

B.Y.O.B. wrote:
Mon Nov 12, 2018 1:10 pm
It would be best to have a much more simple scene, just the elements that cause the difference.
You can help us developers a lot by making test scenes as simple as possible, while still reproducing the problem.
And then it's best to open a github issue, posts in a long thread get lost very easily, while github issues can be tagged and searched much better.
Sincee Dade explained, I use architectural glass for path renders. In a short and rather simple scene I tested with glass rough CPU and GPU and found no issue in beta 1.
The bath room scene was a bit more complex because I found some strange effects using DLSC in more complex scene which was not reproducible with the simpler scene.

That is true, in github it is much easier to find entries.
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Re: Denoiser CPU and GPU different results.

Post by FarbigeWelt » Mon Nov 12, 2018 3:06 pm

Dade wrote:
Mon Nov 12, 2018 2:00 pm
FarbigeWelt wrote:
Mon Nov 12, 2018 12:33 pm
„Green light of LED bar (white point lamps, irregular data color input for glass' transparancy) is not visible with GPU path and only slightly visible with CPU Path but is overall visible with CPU BiDir.“
As I have explained answering to that post: Path can not render lights beyond specular surfaces while BiDir can.
I remember your explanation. My example here is a not a very appropriate one but the only one I have a record for. Still I think I observed different behaviour of CPU path and GPU path, but have to recall first and model them.
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Re: Denoiser CPU and GPU different results.

Post by B.Y.O.B. » Mon Nov 12, 2018 3:14 pm

Dade wrote:
Mon Nov 12, 2018 2:00 pm
As I have explained answering to that post: Path can not render lights beyond specular surfaces while BiDir can.
But that aside, shouldn't CPU and GPU path match each other?
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Re: Denoiser CPU and GPU different results.

Post by Dade » Mon Nov 12, 2018 5:21 pm

B.Y.O.B. wrote:
Mon Nov 12, 2018 3:14 pm
Dade wrote:
Mon Nov 12, 2018 2:00 pm
As I have explained answering to that post: Path can not render lights beyond specular surfaces while BiDir can.
But that aside, shouldn't CPU and GPU path match each other?
Yes (but it is 150 samples Vs. 1500, hard to say with lights beyond glass and path tracing).
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