glossiness 1.0, white dots in gi

[mahorela]

Hi

I'm using Corona version: 2 (Release Candidate 4) and for the first time ever, I've noticed that my glass windows (well, anything with reflection glossiness at 1.0) are generating white dots (tiny fireflies) in the indirect lighting. This in turn is visible in the beauty pass.

I'm using a model exported from revit, it's the first time I've used models from this particular client, everything has been re-textured etc though.

Anyone seen or solved this yet?

Cheers

[maru]

Hi, is there any specific reason why you are using the V2 RC4 version? Can you please install the official V2 release? https://corona-renderer.com/download/
Models exported from Revit/Cad software are known to cause various issues with shading. Can you check if new geometry created in 3ds Max (e.g. box) shows this issue as well?
Are you using some environment overrides in the Render Setup > Scene tab?

[mahorela]

Thanks Maru

My bad, I upgraded to the wrong version, I now have the latest version installed and it hasn't fixed the problem.

Upon further investigation, I think it's a caustics problem (the standard kind, not the slow kind).

White dots_01 shows the effect on the beauty pass. white dots_02 shows the gi pass and the weird tiny caustic effect happening on a material in the scene that has glossiness at 1.0. White dots_03 shows the effect clearing up when I add the material to a rayswitch with the GI glossiness set to 0.0.

I was messing around the other day trying to to pool caustics using the tools in the dev mode. Somehow I think I must have changed some settings that have reflected on my caustic settings even after I have switched the render engine back from PPM to progressive. I have uninstalled and reinstalled Corona numerous times and merged this scene into a fresh scene and created the render settings from scratch (without messing with the dev tools) but still the problem remains.

Any way I can reset these to default values?

Cheers

[Vlad_the_rant]

Does reducing Max sample intensity change anything?

[mahorela]

Nah, first thing I tried. The only thing that fixes it is to add a rayswitch to the material and push the reflection glossiness in the material applied to the GI channel to 0.0.

Hardly something you want to do for every glassy material.

[mahorela]

Oh and it doesn't matter about the geometry, I remade the glass panes in max and it still happened.

[maru]

I am afraid we will have to take a look at the scene to find out what might be wrong. Can you upload it using https://corona-renderer.com/upload and tell me what's the file name? (or a simplified version of the scene - with the problem visible)

[Fluss]

That's a refraction issue I guess, try to enable thin (no refraction) and see if fireflies are still there

[mahorela]

Ok so sorry I haven't been responsive, I've been swamped.

Putting the MSI back to 1.0 did clean up the noise although it's hardly ideal either. The only way I could solve this was to load a scene from before I started to mess with the dev settings and save out a preset and then load the preset.

I'm sticking to the original hypothesis that something I changed in the dev settings while experimenting with pool caustics baked into the render settings.

Let me know if you'd still like me to upload a scene, I faced this problem on all scenes not just that one. I'd wager that I could save out a render preset and you could apply it to any scene and it would generate the same white pixels.

[mahorela]

This looks like what I'm facing;

https://corona-renderer.com/stuff/helpdesk/caustics/msi0-30min.jpg

But there's no "slow caustics" in my scene and the msi is 20

[maru]

Moving to resolved. Explanation was probably messing with some development settings. Feel free to bump in case of still having this problem (or similar).