Frosted glass in mirror reflection

[ler01]

It looks like a bug to me. But if I'm wrong and it's just because I'm doing something wrong please move this thread where it should be.
So the problem is on the attached image - in direct view frosted glass looks fine but in it's reflection in the mirror looks very weird. I'll attach mirror and frosted glass materials settings.
Thank you

[ler01]

Update: I turned on caustics in glass material and for one view it was enough. But on another view the glass in reflection got another flake artifacts. And to get rid of them I had to switch from UHD cache to path tracing. Flakes gone but it took like forever to render even in region.

[cecofuli]

You should try to reset Corona settings.

[maru]

1. Can you completely remove diffuse for this material? (either set diffuse level to 0 or color to pure black) Or maybe it is important for this material to have it?

2. There was a bug in Corona 1.5, and the solution is to download the newest version (1.5.2), open your scene, and click "reset settings" in "scene" tab. This will revert UHD Cache settings to safe defaults (which are NOT accessible from the ui otherwise).

3. If there are still some problems, it would be great if you could share the scene with us.

[romullus]

I don't think it's UHD cache related. I stumbled upon similiar behaviour too, not so long ago. Didn't think about reporting it though. I will see if i can find that scene and will provide more details or scene itself if required.

[ler01]

Hi guys. Thanks for attention) I have corona 1.5.2 I've created a new scene and merged there part of the scene including mirror and frosted glass door. Render settings were untouched and the result is the same - when caustics are off - glass door in the mirror rendered like it has refraction glossiness set to 1. When caustics turned on door in reflection has normal glossiness - just like original but has flake artifacts - the same as on pictures in my previous posts.
Setting diffuse level to 0 doesn't change the thing.
I'll attach the scene file.
Also on another similar scene I noticed another weired behaviour but also related to glass reflection in the mirror. This time glass doors had glosiness set to 1 but material had some absorbation. And while I had caustics turned off  - the glass doors looked weird in the mirror reflection and after turning caustics on the reflection became normal.
So generally what is really weird is why turning caustics on and off affects objects reflected in the mirror more than same objects seen directly

[romullus]

I noticed that your mirror has 0.99 reflection glossiness. Try to set it to 1.0 and weird behaviour should disappear. That is exactly the same behaviour i was talking in my previous post. I found that scene and reprodused the bug. As i said, i can share scene with Corona team if needed.

[ler01]

in fact - yes. Changing mirror glossiness to 1 resolved issues in both scenes.
Well doesn't really matter to me now because I already have final images for both scenes. It's more for developers and for other people to let them know how to resolve similar problems.
Anyway I would consider this as a bug. Because changing glossiness to 1 might be not an option in some other situations.

[SharpEars]

I noticed that your mirror has 0.99 reflection glossiness. Try to set it to 1.0 and weird behaviour should disappear. That is exactly the same behaviour i was talking in my previous post. I found that scene and reprodused the bug. As i said, i can share scene with Corona team if needed.

Is 1.0 a safe value for glossiness though, or is this one of those values that has to be <1 to be "physically realistic?"

[romullus]

There's no reason to set reflection glossiness to 0,99 just hoping that it will make your materials more realistic. I doubt you will see any difference between glossiness 1 and 0,99 but in the case of latter, renderer will have to make more complex calculation, which may lead to increased render time or even various artifacts.

[alexyork]

There's no reason to set reflection glossiness to 0,99 just hoping that it will make your materials more realistic. I doubt you will see any difference between glossiness 1 and 0,99 but in the case of latter, renderer will have to make more complex calculation, which may lead to increased render time or even various artifacts.

Disagree with that. In quite a few cases we're finding that tweaking the glossiness from 0.999 to 0.998 produces a very visible difference at full res. Makes a really big difference the realism of mirrors and complex glasses like antique glass etc.

[maru]

Reproduced with 1.6. Enabling caustics immediately fixes the issue.
Another problem with fake glass. :/

Attaching simple scene.