Caustic does not work in glasses, Photon Tracing Kernel Tweet

[Elvissuperstar007]

How to work with caustics? I do everything according to the lesson, from metals the caustic is very weak, but there is, but from glass there is no caustic at all
increasing the power of the light source does not give any effect, the IOR setting also has no effect, The checkbox for displaying caustics in the material is selected

OctaneRender® for 3ds max v2024.1.2 - 15.12
https://help.otoy.com/hc/en-us/articles ... ing-Kernel
3ds max 2025.3
win 10
4090 rtx
566.36 game ready

[skientia]

That is caused by a too-large light, which results, just like shadows, in a softening of the caustics.

From this Caustics post:
The larger light in this .gif is not as large as in that 3ds max project file, but the larger, the more "diffused" (softened) and "disappearing" the caustics becomes.

[paride4331]

Hi Elvissuperstar007,
The caustics are working, so the issue might be with the scene setup. It looks like you're using a very large light source, which naturally creates diffuse shadows and tends to diminish the caustics. On the other hand, point-like emitters will emphasize the effect.
Regards
Paride

[Elvissuperstar007]

Hi Elvissuperstar007,
The caustics are working, so the issue might be with the scene setup. It looks like you're using a very large light source, which naturally creates diffuse shadows and tends to diminish the caustics. On the other hand, point-like emitters will emphasize the effect.
Regards
Paride

I made a scene according to the lesson
https://help.otoy.com/hc/en-us/articles ... QuMzIuMC4w

[skientia]

The key is a smaller light source. The information on the provided images indicate the lights are several meters (3-4m) large, akin to a large softbox in reality, or diffuser frame ("scrim"). This will effectively produce caustics as any light source will but in a too-subtle way, softened and diffused: much less apparent.