Hybrid Back/Forward path tracing (aka BiDir without MIS)

[epilectrolytics]

Glossy caustics didn't work for me either in Blender, so I went after it, and it seems, that it dosen't work without the "path.hybridbackforward.glossinessthreshold" parameter.

- Didn't work in Blender
- I exported the scene from Blender => didn't work in LuxCore UI
- I added "path.hybridbackforward.glossinessthreshold = 0.05" line in render.cfg => now it works in LuxCore UI

Glad you figured that out, I was just going to look into it after my animation was done

[epilectrolytics]

I might have found a bug:

I also observed that fireflies don't disappear when I disable specular visibility in the lamp properties.

[Dade]

In newer LuxCore UI LightCPU engine doesn't trace certain paths. The image in the mirror doesn't seen at all.
The version from June 21 of is working fine, the June 25 is no longer.

Yes, I removed the tracing of some eye paths, it was there to do some test for BiDir, it is now no more necessary. A pure light trace can not render mirrors and some other stuff, always for the same reason: you can not connect a light path specular vertex to the eye.

[provisory]

Yes, I removed the tracing of some eye paths, it was there to do some test for BiDir, it is now no more necessary. A pure light trace can not render mirrors and some other stuff, always for the same reason: you can not connect a light path specular vertex to the eye.

Oh, I see... it seemed promising for SDS treatment in some cases...

[Dade]

Have started an animation, but when motion blur is activated light tracing does not work

It was a general LIGHTCPU, BIDIRCPU and now Hybrid problem. I should have fixed camera motion blur.

[happyboy]

You may be using a version with an initial bug, it has been fixed so try to update your binaries again.

Ah, yes! I'm tested the latest binary and it works now!

[epilectrolytics]

It was a general LIGHTCPU, BIDIRCPU and now Hybrid problem. I should have fixed camera motion blur.

Thanks for fixing it, tested and found it working!
(build 20190626.1)

But now the infinite lights are off again:

and the scene I animated yesterday is a total mess with a horizontal split and way too strong caustics

[Dade]

I might have found a bug:
This is a scene with metal material, roughness 0.1, glossiness threshold set to 0.2 so the glossy reflections of this material are handled by the light tracer.
However it looks like the normal path tracer is also still tracing these reflections because they are very noisy.

I should have fixed this problem. This was the rendering with the bug:

and this with the fix:

Note how the fireflies inside the caustics are now gone however the one from SDS paths are still there. Variance clamping can be used to keep them under control.

[Dade]

But now the infinite lights are off again:

horizontal split and way too strong caustics

Try again (with the under construction build).

[epilectrolytics]

Try again (with the under construction build).

While the concrete scene works again, still my glass cubes won't show sky reflections.
(left:BiDir, right: Hybrid)

testanim+_LuxCore.zip

(39.44 KiB) Downloaded 189 times

When hybrid lightpass always uses metropolis sampler, would we need to adjust the settings in certain situations?
In my testing it works just fine in all circumstances and I don't feel like I have to change anything,
but just in case, are they taken from BiDir or are there extra hybrid metropolis settings?