Long rendering time

[maru]

Correct, we have a simple repro scene, so no need for uploading any other one.

[dj_buckley]

Hm hm, the include exclude doesn't stop the calculations from actually happening. It just removes them from the image so that you don't need to worry about caustics looking noisy in a part of a scene you're not really concerned with - hence you can stop rendering sooner. The calculations do still happen though.

I suggest you render the caustic-y part separately (region, selected mask etc.) and all the rest in another render. That should bring reasonable render times.

But from your Caustics article here - https://support.chaos.com/hc/en-us/articles/4954589213457-How-to-render-caustics-with-the-caustics-solver-in-Corona-for-3ds-Max

"There are also some limitations:

Caustics may render slower/differently when using render regions. The smaller the region the harder it is for the caustics solver to optimally guide photons. "

[maru]

In case of region-rendering a small object like a glass on the table it shouldn't be a problem.

[Tom]

But from your Caustics article here - https://support.chaos.com/hc/en-us/articles/4954589213457-How-to-render-caustics-with-the-caustics-solver-in-Corona-for-3ds-Max

"There are also some limitations:

Caustics may render slower/differently when using render regions. The smaller the region the harder it is for the caustics solver to optimally guide photons. "

I confirm this point: caustics on the table look different when rendered with 'Region render', compared to the whole scene being rendered (see attached the region render, and the whole scene cropped to the region render).