LuxCoreRender Forums

When using a HDRi with light tracing, it looks like the shadows are a lot darker, as if only the sun is used in the image. This seems to only happen when using OpenCL, CPU looks as it should.


There are also a lot of fireflies in this scene, not sure why as caustic paths should be accounted for with the cache.

What LuxCore version are you using ?

Latest build V2.4

Your scene seems to have only a 2% of light rays (this is like enabling light tracing and than not doing it)

@B.Y.O.B: wasn't the light tracing % hidden and set to 100% automatically with OpenCL

Dade wrote: ↑Thu Apr 09, 2020 3:35 pm Your scene seems to have only a 2% of light rays (this is like enabling light tracing and than not doing it)

Note: the same happen if you render in OpenCL with light tracing enabled (that is done only on the CPU) and 0 CPU threads.

I made it possible to use less than 100% light rays even with OpenCL after JuanGea pointed out that very powerful CPUs are a waste to use for only caustics.

Maybe I should set a lower limit for light rays though, something like 20%.

B.Y.O.B. wrote: ↑Thu Apr 09, 2020 3:57 pm I made it possible to use less than 100% light rays even with OpenCL after JuanGea pointed out that very powerful CPUs are a waste to use for only caustics.

Oh, ok.

B.Y.O.B. wrote: ↑Thu Apr 09, 2020 3:57 pm Maybe I should set a lower limit for light rays though, something like 20%.

Using 0% (or 100%) can be still useful for some trick (like getting only light tracing or only eye tracing output for compositing) so I guess we can leave it as it is.

Ok.

Light Rays was set to 100% using OpenCL, the 2% was only on CPU rendering (which had the correct result).

Just to clarify what the issue is here, the CPU image looks as it should, but the OpenCL image has the shadows much darker. The Light Tracing % was set to 100% for OpenCL, and set to 2% for CPU. I only set it to 2% as I didn't need the default 20% as the caustics would get clear much faster than the rest of the scene