White speckles problem

[Giulio-NeP]

Hi all,

I'm writing to report a problem I have with glass materials in general.
Sometimes it happens that white speckles appear on the glass (probably reflections) and they don't go away, no matter how many passes you do.

Please find image attached,
Thanks in advance,

Giulio/N&P

[maru]

What kind of light are you using (the thing that is refracted inside of this noisy area)? I would also check for geometry errors as I can see parts of flowers intersecting with the glass.

[Stan_But]

Also try to set diffuse color in 0.0.0 or diffuse level in 0.0

[Giulio-NeP]

Hi guys, thanks for your help!

I tried changing the diffues parameters but the noise was still there.
The lights that are causing this noise are two long and narrow lights on top of the mirror (see image attached).

No problem if we switch those lights off or exclude them from reflections/refractions.

I had the same problem with a chandelier that had very small and powerful lights, that's probably the thing.

Thanks very much,
Giulio

[maru]

Mirror + light + refraction. It could be an instance of this: https://forum.corona-renderer.com/index.php/topic,5628.msg38930.html#msg38930
You could try making the light invisible in reflections only and see what happens. Or maybe rayswitch could help here. I will get back to this.

[maru]

Here is my result + max file. Not sure how close it is to your scene. My advices:

-use diffuse level 0
-maybe the light source is too strong?
-try increasing system>frame buffer>internal resolution to 2
-increase highlight compression
-render in higher resolution, then reduce size
-decrease gi vs aa balance (to 8? 4?) this will result in better antialiasing in the same time, at the cost of GI quality

[Giulio-NeP]

Thank you so much Maru, I tried to change system parameters etc.. but nothing good happened.
I switched caustics on, changed the diffuse in the glass material but same white noise.
Lowering the power of lights or disable reflections/refractions helped and the noise did go away... but I don't know if we can call it a bug...

Thank you again for all your efforts!
Giulio