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Cycles denoising: black bars and motion-blur like distortion w/ GPU rendering
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Description

I've had some troubles with the Cycles Denoising (which is a wonderful feature).

In some projects it produces anomalous black bars and/or black spots on my renders.

I did some testing with the newest nightly build. The artifacts are only present when using GPU for rendering, CPU produces flawless images:

CPU:

GPU:

You can also see that the GPU render produced a skewed noise pattern. like there is some motion blur in the image, although nothing is animated ,and it's the same scene, so it should look the same. I used very extreme settings to trigger the problems, but they sometimes happen in real-life scenarios without resorting to stupidly low sample counts. I initially thought that the issues are triggered by a holdout shader being used in the scene, but it doesn't seem to have any effect.

Here's my test project:

Event Timeline

Lukas Stockner (lukasstockner97) triaged this task as Needs Information from User priority.May 16 2017, 4:11 AM

Hm, I never encountered that kind of problem before - what GPU are you using?

YAFU (YAFU) added a subscriber: YAFU (YAFU).EditedMay 16 2017, 5:34 AM

Hi.
Here's what I get in Blender from buildbot ( 8ca9fa5fd36 ) with GPU:

Kubuntu Linux 14.04, GTX 960 ( driver 378.13)
Tiles: 480x360

I think it's the same problem about black patterns around tiles after denoise that I get here:


In my tests with my file, problem is much more evident with low samples rates. But anyway, with high sample values the problem can also occasionally be presented.
Black patterns are not always the same, this can vary on each render.

The problem does not occur in experimental build ( rB82bcfb9b342a ).

I'm using MSI GeForce 960 2GB, driver version 361.42 under Linux Mint 18.1 with KDE5.

Fixed with rBffd83a34ab53, thanks for the report.

Wonderful! I can't wait for a new build :D
Thank you!