Weird behavious with caustics, object not receiving ANY caustics with a roughness below 0.23

[juangea]

So that's the thing, I was becoming crazy because my precious caustics were gone.

Today I had a bit of time to separate components and investigate and I found this, this is an example scene, notice the roughness value and the result render, it's final render, with caustics cache, but it affects also light tracing:

Now notice that I raise the roughness value to 0.23 instead of 0.22:

Here is the exact same file used in those renders, just open it, launch render, then lower the roughness and check the result:

https://we.tl/t-9INjKEA2Av

[Theverat]

The roughness input of the disney material is squared internally. 0.22² = 0.0484 0.23² = 0.0529

So it probably has to do with the default roughness threshold of 0.05 in the light tracing/PhotonGI cache settings.

[juangea]

Interesting, but that means that ANY kind of caustics would be disabled over a surface with less than 0.22 as roughness?

Because I would expect that from disabling it from light tracing, but also from caustics cache?