Corona 4 for 3dsMax - Exclude objects from Caustics

[MaryKrivo]

Hi everybody!

I'm testing a scene with new corona caustics, I would like to ask if anyone knows how or if it is possible to exclude some objects from caustics?

My scene is an exterior with a pool, I've put a sun that just lights the pool water, in order to obtain caustics, but I'd like that the caustic effect is just visible on the water and on the pool tube, and not on everything in the scene, also to speed up the rendering time.

Is it possible to exclude/include objects in the caustic effect (like we do for lights for instance).

Before anyone asks, I've already tried to render just the pool, but I don't like the final result (there are bloom&Glare effects applied) and I need to render the scene just once.

Thank you.

[maru]

Sorry, but I don't think this is possible right now. You can only toggle caustics globally (on/off), toggle refractive caustics per material (caustics checkbox under material's refraction parameters), and toggle caustics for Corona Light objects ("generates caustics" checkbox).
Controlling where the caustics should appear, which objects should receive them, and which specific objects should generate them is among some of the most common caustics-related user requests, so we will definitely come up with a solution to this as quickly as possible.

[maru]

Just a small confirmation:
Including/excluding specific objects from receiving or casting caustics is currently limited (other than using the "caustics" checkbox in a material to disable refractive caustics, or using Corona Light includes/excludes).
This seems to be one of the most commonly requested features, so we will definitely look for a solution to this.

[Vlad_the_rant]

The ability to include and exclude objects entirely from caustics is currently not possible to implement with the caustics solver the way it is.

[aaouviz]

Sorry to dig up an old thread...

To continue this discussion, I understand that turning caustics on/off for objects is not possible. Fair enough, the 3 other tick boxes should be able to do a good enough job...

However, I'm playing around with Caustics today for the first time in a while.

I have a glass, a table and sun. Renders perfectly, caustics look great! The glass has caustics turned on, the sun too, but the table not.

When I put the same glass, table and sun into a 'complete' scene, the caustics basically fails - very blurry, very noisy nothing like the simpler scene. The sun is the only light source with caustics enabled, no other objects have caustics ticked (though, with 100 or so materials, is there any fast way to confirm this?). The sun light is uninterrupted (ie; doesn't travel through a window pane) when hitting the glass.

So why the big difference? Is this just how it is? All the other objects in the scene affect the caustics? If I have buildings across the street they're messing up my nice caustics, for example?

Or am I missing something/doing something wrong?

Thanks for any clarification!

[maru]

Caustics will always render faster / better in simple scenes than in more complex ones. The easiest solutions to deal with this would be:
- Disabling reflectivity / refractions (either directly or using the rayswitch material) for other objects in the scene, which would otherwise "steal" performance
- Focusing the caustics-casting light only on the area where caustics are needed - e.g. you can disable caustics for the global sunlight, and enable them for a smaller light which would be hitting the caustics-generating objects only
Of course both solutions are partly fake.

If you can share the scene, please do. We will see if we are able to optimize it (or the caustics solver): https://corona-renderer.com/upload