Black artifacts

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Taka
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Black artifacts

Post by Taka » Mon Nov 08, 2021 6:31 pm

Hi there,

I've been having a problem with some places rendered as black. If I change the angle of the camera, they disappear.
I'm using Blender 2.93.5 with Luxcore 2.6 alpha0. If I render with Luxcore 2.5 on Blender 2.92, these spots are less noticeable and they look like dark stains. Link to simplified file:
https://www.dropbox.com/s/nma9s7b79ui2z ... blend?dl=0

It was made in Marvelous Designer. Does anyone know what causing this?
Attachments
K_04_MasterBR - LR Cropped.jpg

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B.Y.O.B.
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Re: Black artifacts

Post by B.Y.O.B. » Mon Nov 08, 2021 7:54 pm

Have you checked for duplicate faces?
https://wiki.luxcorerender.org/BlendLux ... nal_render

Luximage
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Re: Black artifacts

Post by Luximage » Mon Nov 08, 2021 8:01 pm

It seems to be caused by the normal map in the bump slot. The results for the cpu and gpu are different(latest blendluxcore).
I tried an older blenluxcore 2.6 version i have and the results from the cpu and gpu are the same.
Furthermore if you change in the normal map node from OpenGL to DirectX the result is better.

Taka
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Re: Black artifacts

Post by Taka » Mon Nov 08, 2021 9:28 pm

Thank you both for looking into the issue. I checked the duplicates and there is none. Yes, Luximage, If I lower the normal map strength, the black spots disappear but so as bump effects. I wonder why it renders differently from version to version (in my case 2.5 and 2.6 alpha0).

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Dez!
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Re: Black artifacts

Post by Dez! » Tue Nov 09, 2021 12:03 pm

1) Check the camera settings. Make the area of what the camera sees as small as possible.
https://i.imgur.com/h6wyZgz.png

2) If that doesn't solve the problem, study these settings: https://i.imgur.com/4wkeDdF.png
Changing the minimum value has a noticeable effect: https://i.imgur.com/TUlKWEy.png
I've had cases where this setting helped: https://i.imgur.com/InP5Jpw.png
Careful, increasing the maximum value increases the time to prepare the scene for rendering when using the GPU
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Taka
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Re: Black artifacts

Post by Taka » Tue Nov 09, 2021 4:47 pm

Hi Dez!, thanks for your suggestions, but they don't seem to help with my scene. Besides, every time I change the "epsilon settings", Luxcore re compiles the kernel, another wait for 5 ~ 10 minutes.

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Dade
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Re: Black artifacts

Post by Dade » Wed Nov 10, 2021 9:50 am

I'm running the test scene but it looks like it is working fine here:

black.jpg

Am I missing something ? What result do you get ?
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Taka
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Re: Black artifacts

Post by Taka » Wed Nov 10, 2021 4:10 pm

Sorry, I decreased the Normalmap Height before saved the file.
If you increase the height, here is a result I get.
Attachments
Capture.JPG

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Dade
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Re: Black artifacts

Post by Dade » Thu Nov 11, 2021 9:31 am

Taka wrote:
Wed Nov 10, 2021 4:10 pm
Sorry, I decreased the Normalmap Height before saved the file.
If you increase the height, here is a result I get.
It is still working fine here even if I set the height to 20.0 but I think you have just forget to include the relevant normal map:

Code: Select all

WARNING: Node "Imagemap.001" in tree "Duvet_FRONT_2": Could not find image "Seamless_crease_Blur_Normal_GL.jpg" at path "//../04_Shader/Fabric/Seamless_crease_Blur_Normal_GL.jpg" (Not an existing file: "/home/david/tmp/blackbed/../04_Shader/Fabric/Seamless_crease_Blur_Normal_GL.jpg")
You included "Seamless_crease_Blur.jpg" file but not "Seamless_crease_Blur_Normal_GL.jpg".
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Taka
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Re: Black artifacts

Post by Taka » Fri Nov 12, 2021 8:49 pm

Dade,
Thanks for your help. I re-packed the file so it should include the normal map. Could it be a problem with my gpu? With cpu rendering, it's less noticeable. I will try with different gpu at home tonight.

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