Caustics flickering in animation

[Aram Avetisyan]

Thanks for the test and reporting back.

Can you please try one last thing: try with 4K Cache (or UHD Cache) as secondary solver and set it to, if not already:

Precomputation: Try to load + append
After render: Save to file

Let's see if this brings improvements.

[Norma]

Doesn´t seem to improve.
See attachement.

Notes:
Primary: Path Tracing
Secoundary: UHD Cache
Animation (flicker-free)
Precomp: Try to load + append    After render: Save to file

Noise level x frame: 5% + Corona Denoise.

[Aram Avetisyan]

Thank you.

This is yet another "research" for this topic we will add to the investigations, so thanks for your efforts.

[maru]

@anyone with the flickering caustics problem - could you please try this kind of setup? (see screenshot)

What it does: the water material is just a regular water material with caustics enabled. No need to change anything in its settings. Then a Corona Rayswitch map is connected to its opacity slot (Rayswitch map, not material). The Rayswitch map has pure white color in all its slots, but a slightly darker color in the Global Illumination slot. This means that the water material is fully opaque for reflections, refractions, and when seen directly, but it is semi-transparent to GI. This way the caustics generated by the water material will be slightly weaker (less contrasty) but it can also help with flickering. The color used in the GI slot should be determined by trial and error. Set it to bright gray and render a few frames. If there is still flickering, make it slightly darker and try again.

Unfortunately, Corona caustics do not have "temporal consistency" so they will have a different pattern on each frame and this may cause flickering:
"The new caustics use a Markov Chain Monte Carlo algorithm, which means each frame in an animation (or even rendering the same frame twice) will have a different pattern in the noise. To avoid flickering in animations, you will have to render a significant number of passes to ensure the solution has converged. "
Source: https://support.chaos.com/hc/en-us/articles/4954589213457