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Haha, yes, after (de)activating all kinds of caches and rendering modes, I found out that the specular difference is simply a matter of switching between GPU and CPU, where the CPU result looks considerably better.

You can see the difference in this post.

Thanks, I thought so too.

BYOB already has my pumpkin scene, so he can check it out. If his findings are not the same, it might be caused by my hardware configuration.

Eager to find out what causes the very noticeable difference in specular highlights between Path + Sobol and Bidir + Metropolis , I did some testing...

I error-trapped by switching off all kinds of Path + Sobol settings to see if the specular highlight behaviour of Bidir + Metropolis would appear ...

Thanks for the explanation, appreciated!

So when I use area lights surrounding a scene (along with a HDRI environment), Bidir + Metropolis should have no limitations, and will even calculate SDS paths?

And by "intersectable", do you mean a light should have at least a little volume, or does only ...

I'm wondering: is Bidir + Mis not able to render SDS paths at all, or is it able to do so if the light has some area or volume? (Not a distant sun or point light.)

Nice!

Yeah, I worked with Renderman for a while, which also has a bidirectional VCM engine. The results are quite nice, but once Blender 2.8 was released, Renderman support was left behind in Blender 2.79.

Early 2021 there will be renewed Renderman support for Blender though, so Luxcore devs, just ...

Bidir + Metropolis can't do SDS caustics, so at least the Caustics light cache would be an "advantage" for Path. I'm also with Sharly as in I don't even see any obvious SDS paths there. Maybe in the knife reflection onto the pumpkin-eye carving, but there is only diffuse lighting arriving there ...

I just figured to activate all settings that bring the Path engine closer to the Bidir + Mis result, for the best quality. But it turns out that Bidir + Mis still has the edge.

I just discovered that Bidir + Metropolis has a noticeable advantage over Path + Sobol + Light Tracing + Photon GI Cache + Caustic Light Cache.

Would it be possible to accelerate Bidir + Metropolis using the GPU?

Dez! wrote: Thu Nov 05, 2020 9:30 am what purpose do you pursue by uploading such huge images to the forum?

Haha, no purpose. Just forgot to convert them to JPG.

It seems that all specular highlights are more prominent in the Bidir + Metropolis rendering, and the SSS also is a bit lighter, with a more gradual falloff.