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Path OpenCL (CPU+GPU and only GPU)


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Did you used the same amount of samples for the test ? The GPU rendering looks sharper/better but it could just due to the higher amount of samples per pixel.

the settings are the same. I just switch OpenCL to CPU.
In compositing, if you look at the node render layer, the images in the channels are the same. The results differ only in the channels of the Denoiser.

Dez! wrote: Wed Oct 31, 2018 6:02 pm the settings are the same.

But you did not specify the "Samples" halt condition.
So it could be that they have a different amount of samples.

B.Y.O.B. wrote: Wed Oct 31, 2018 6:17 pm

Dez! wrote: Wed Oct 31, 2018 6:02 pm the settings are the same.

But you did not specify the "Samples" halt condition.
So it could be that they have a different amount of samples.

And why does the processor and video card have different understanding of the noise threshold?


Yes, indeed, the processor makes fewer samples with the same amount of samples installed.

With an equal number of samples from the CPU and the GPU, the result is the same. The picture is blurry again.
Before denoise pictures look the same.
This denoise works differently between the CPU and the GPU.

Yes, I am researching now.
Denuser settings work differently for the CPU and the GPU.

everything i found the reason. value Histogram Distance Treshold works differently.

Working with a long animation, I noticed another problem.
If in OpenCL mode you disable the use of the processor, the denoiser may hang.
The system resource monitor at the same time shows 100% CPU usage. But in fact the system is not loaded. And it lasts forever. I tried to wait the whole night, but no, this is a hangup forever.
This does not happen all the time. I have not figured out what it depends on. But it happens quite often.
I could not render more than 100 frames in one approach, the deoiser will definitely hang.

Am witnessing somewhat small inconsistencies in final result statistics, while comparing GPU vs CPU usage.
I assume since GPU does computing far faster using different packaging than CPU, results may vary. Difference is very small and not visible to the naked eye.

Also, a small error can escalate faster and turn into a bug, a halt or a crash. In my case, sometimes, when denoiser doesn't do it's job, the frame is saved black, but the rendering sequence continues. I never had a hanging situation with LuxCore. Since i got ECC memory on GPU and CPU... I wonder, if it could be it, but i don't know how to test the assumption. There are also many other factors that could sprout bad behavior (applications running in back, faulty hardware... as in one case i had network card polluting the system environment, got some freezing & hanging).

Would you care to make a study scene for testing purposes?