Glass banding

[RenoJ]

Tring to figure out of this is normal behaviour or not.

The glass (Glass preset physical material) is showing up these bands if I put a chamfer or fillet on the edges.

There is just the box, plane and one light in the scene. I feel it must be bouncing the reflection of the glass edge back and forth but I dont know why.

Anyway to stop it even if it is normal?

[romullus]

No, that's not normal. Since you mentioned chamfer, first thing i would check are normals. Adding chamfer without support loops may lead to incorrect shading and refractive materials are extremely sensitive to that.

[RenoJ]

Thanks for the reply, it happens even with corona round edges as well, which I would have thought doesn't need support loops?

The geometry is just a primitive box.

[pokoy]

Chamfer applies smoothing groups to the entire object, try to tell it to smooth chamfers only and tick on 'smooth to adjacent', this is the more correct approach anyway.
Also, make sure your glass object doesn't overlap with the object/plane below it. Overlapping faces will result in artifacts.

[romullus]

Maybe it's a scale issue? Could it be that your box is extremelly small, or extremelly large? Or it's very far from scene origin.

[RenoJ]

Ok tried a new scene but same issue.

Corona round edges on a box shape 30x300x300mm zero'd on the origin. Units set to mm.

When I turn off smoothing if using the chamfer modifier it goes really crazy like I've put a large noise map in the bump.

Would it be possible for someone to try the max file and see if it happens with them too in case its something to do with my settings?

Thank you in advance!

[pokoy]

Tried the file, nothing wrong here.
I get it now - you mean the stripes? These are total reflections, the edge keeps being reflected internally off and off again until it finally fades.
Chamfer and smoothing - if you set 'Smooth chamfers only' and check 'smooth to adjacent' it will look exactly like the rounded edges version.

Not sure what else to say. If you think Corona does it wrong, try using a different renderer to check against - if it looks the same, it's just how rays work.

[mferster]

Looks correct to me, I think it just looks weird at theese particular proportions of glass , if you increase the height of the box while in interactive render mode I think it will become clear how it is working physically.