Caustic Shadows

[podperson]

Blender 3.2 just added shadow caustics for Cycles and it's a definite improvement for Cycles. but points to just how amazing the Cheetah renderers are/were because both were able to do both shadow and reflection caustics better than Cycles can now (albeit Cycles is much easier to set up, you just toggle on shadow caustics for a lamp and it "works" for low values of "works").

I haven't spent nearly as much time tweaking the blender scene as I did, once upon a time, with the Cheetah 3D scene, but I was able to more-or-less duplicate the lighting setups and the materials are pretty close. The Cheetah image is far richer in terms of internal reflections and caustic shadow detail. I took the stats shots around the 100 sample point, but I wasn't able to figure out how to export the blender render until it got to 250 odd samples. To my eye the C3D render looked slightly cleaner at ~100 samples than the Cycles render, but obviously it took a fair bit longer.

All of this was on an Macbook Pro with an M1 Pro Max.

Edited: put images inline and added C3D render (which was rejected due to size).

C3D 7.5.1 Falcon

Blender 3.2 Cycles

 

[podperson]

What C3D does is pretty nice, but it's a long way from realistic.

Here's a photo of a much less intense light producing clear tinted bright spots in shadows of a glass of scotch.

Under a more intense and concentrated light (the sun) you can see that the "shadow" is in many cases BRIGHTER than the fully lit surface because the glass is focusing light onto it. Meanwhile, you can again see a VERY bright tinted shadow.

It's possible to get something of this effect using Falcon, but not at all in Cycles (well, I can't do it).

And now I'm going to drink that scotch…

 

[podperson]

I've posted this before (and I'm not positive it renders the same way in the current version of C3D) but it does show that caustics in Falcon can produce bright spots in a single pass render.

 

[misoversaturated]

Somehow you have managed to talk about caustics without mentioning LuxCoreRender
Also Blender is adding path guiding right now which is much more caustics complete than MNEE and will be nVidia Optix compatible compared to LuxCore's light tracing CPU only approach.
Regarding Cheetah3D their caustics are somewhat similar to the previous Blender approach via glossy/caustic filter though much nicer.
But with any kind of accelerator missing (GPU rendeing, denoiser, ...) it's simply not possible to put up anything competitive right now.
(I have provided several Cheetah3D Falcon caustic renders during the v7 beta times but without access to user attachments in this forum I'm unable to find them anymore )