Chaos Corona Forum

Chaos Corona for 3ds Max => [Max] Bug Reporting => [Max] Resolved Bugs => Topic started by: maru on 2014-10-24, 15:26:40

Title: Noise in reflected refraction.
Post by: maru on 2014-10-24, 15:26:40

Build timestamp: Oct 14 2014 02:21:33

I'm not sure if this hasn't been reported yet, please let me know.

When there is a glossy reflection of a light seen through a solid glass object, the reflection gets very noisy and the noise does not go away at all. The problem can be observed in this thread:
https://forum.corona-renderer.com/index.php/topic,5325.0.html

I didn't manage to improve it by changing glass parameters, different sampling settings, different light settings, changing from GGX to AS. This also happens to objects with Corona Light mtl (but only if it "emits light"), but odd enough the reflection is more uniform when using CoronaMtl with self-illumination on. Maybe it's a hint?

This does NOT happen to refracted reflections. It also looks ok if reflective material has no glossiness.

Sorry for being so random but I'm in a little hurry.

Images:
r1, r1a - no reflectivity for ground plane
r2, r2a - glossy reflectivity turned on for ground plane
v1, v2 - different views of the problem
refract1 - refracted reflection
SE - self-illumination in CoronaMtl

Title: Re: Noise in reflected refraction.
Post by: maru on 2014-10-25, 17:28:29

hello :/

Title: Re: Noise in reflected refraction.
Post by: maru on 2014-10-25, 20:20:36

here is a bit more "real world" example, light and sun+sky

Title: Re: Noise in reflected refraction.
Post by: lacilaci on 2014-10-26, 10:06:15

You can try to disable "visible in refractions" on your light source, or lowering MSI to a very low value (1?), or try using BiDir..

I would try to avoid this situation from happening (refracted light source being reflected on rough surface)

Not sure if bug or just a standard behavior though...

Title: Re: Noise in reflected refraction.
Post by: maru on 2014-10-26, 16:40:20

This may be really hard to avoid in normal work! Like a glass of water standing on a table...

Title: Re: Noise in reflected refraction.
Post by: Christa Noel on 2014-11-01, 06:56:35

are there someone that would like to explain this? just like lacilaci said, is it a bug or just another kind of standard behavior??

Title: Re: Noise in reflected refraction.
Post by: maru on 2014-11-01, 09:40:39

Yeah, I'm surprised there is so little attention to this topic. Maybe I'm doing something wrong?

Title: Re: Noise in reflected refraction.
Post by: Ondra on 2014-11-03, 17:48:59

This is only another instance of the hybrid glass + reflections bug. It was already reported, changing the glass mode to anything but thin-off, caustics-off helps. There is currently no other solution

Title: Re: Noise in reflected refraction.
Post by: maru on 2014-11-03, 20:41:44

Ok, thanks for the reply. I think this is a really serious flaw.

Title: Re: Noise in reflected refraction.
Post by: Christa Noel on 2014-11-04, 02:47:07

Quote from: Keymaster on 2014-11-03, 17:48:59

This is only another instance of the hybrid glass + reflections bug

what is "hybrid glas"??

Title: Re: Noise in reflected refraction.
Post by: maru on 2014-11-04, 10:10:30

It's solid glass with no caustics (transparent shadows).

Title: Re: Noise in reflected refraction.
Post by: Christa Noel on 2014-11-04, 10:22:42

oh, so it's just a glass that actually has caustic (in real world), and if the caustic effect removed & replaced with transparent shadows, then it named hybrid glass. ok i got it.
thanx