Strange Behavior with OpenCl

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TAO
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Strange Behavior with OpenCl

Post by TAO » Sun Jan 17, 2021 1:15 am

In addition to the last dark render with bump texture on LuxCore 2.4 and up. I keep seeing the same pattern with geometries even with no texture at all. low poly and high poly.
This is happening only with openCL.
Screenshot 2021-01-17 020440.jpg
Screenshot 2021-01-17 020508.jpg
The same scene with CPU render and GPU render.
Also, I can see an EXR image that is not in my scene. not sure why!
tColor2021.zip
(3.08 MiB) Downloaded 13 times
Omid Ghotbi (TAO)
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Dade
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Re: Strange Behavior with OpenCl

Post by Dade » Sun Jan 17, 2021 3:24 pm

It is a numerical precision problem, the size of your scene is HUGE, it is about 200m large.

You can fix the problem by using a realistic size or changing the default epsilon for something appropriate for you scene size:

Code: Select all

scene.epsilon.min = 0.01
scene.epsilon.max = 0.1
The default epsilon values in LuxCore are appropriate for rendering something like a room (i.e. something 4m large). You need to increase the espilon for a lot larger scenes or reduce for a lot smaller.
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TAO
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Re: Strange Behavior with OpenCl

Post by TAO » Sun Jan 17, 2021 3:32 pm

How can I found the exact size of the scene, and is this better to rescale the scene before render or the option you mention will do the same.
Because in 3dsmax the scene is 2m x 2m.
Omid Ghotbi (TAO)
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TAO
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Re: Strange Behavior with OpenCl

Post by TAO » Sun Jan 17, 2021 3:41 pm

And one question, why the rendered result is different from v2.3 and 2.4?
Omid Ghotbi (TAO)
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B.Y.O.B.
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Re: Strange Behavior with OpenCl

Post by B.Y.O.B. » Sun Jan 17, 2021 3:43 pm

In Lux the scene unit is meters. It sounds like your 3ds max is using centimeters. You will have to check if you can change this in 3ds or if you have to convert the units during export (with potential loss of precision).

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Dade
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Re: Strange Behavior with OpenCl

Post by Dade » Sun Jan 17, 2021 3:44 pm

TAO wrote:
Sun Jan 17, 2021 3:32 pm
How can I found the exact size of the scene, and is this better to rescale the scene before render or the option you mention will do the same.
Because in 3dsmax the scene is 2m x 2m.
The .ply are created by you, the numbers written there are big, just check the object bounding boxes or try to just load the .ply inside Blender or 3DsMax if it supports that kind of format.
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TAO
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Re: Strange Behavior with OpenCl

Post by TAO » Mon Jan 25, 2021 10:06 am

I try your solution and it works, in addition, I add the rescaling method so the scene from the 3dsmax scale in the metric system get matches the LuxCore scale factor. As I can see it has a huge impact on the results.
Omid Ghotbi (TAO)
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