
We know - the definition of "Variable caustics" is direct+indirect lights reflected and/or refracted on any glossy (not diffuse) ground:
- (almost) 100% focus of lights direct+indirect reflected and/or refracted -> between 0% and 2% roughness of ground
- low to high blur of lights direct+indirect reflected and/or refracted -> between 2%~95% roughness of ground
- bit or little visible of variable caustics on 95%~99% roughness of ground.
-> Can you understand this?

Difference between my 2 images rendered about variable caustics at 0.09 (9%) roughness of ground:
- At Path Tracing (PT) kernel - I apologize for noises but I needed very, very long number of samples per pixel - At new Photon Tracing with denoiser - quick direct+indirect caustics = only 20 seconds on my RTX 4090 but unfortunately, this is not any variable caustics visible at less than 0.3~0.4 (30%~40%) roughness of ground -> But this new kernel seems to be NORMAL.

--> I'll post to add new image at PT kernel in this night when the new image will be rendered (the camera little moved to right from camera original (see 1st image)).
