I have a clients product with beveled edges. I am getting really wierd edges showing up. The glass looks great everywhere on final renders but the edges keep getting these lines. The bottom pane of glass is the one I am trying to use but I have tried straight cut, rounded edges. I have tried beveling the edges so there are no sharp lines assuming the geometry is too perfect. I can’t seem to find a good solution. I have tried making the samples as high as they can go on glossy, transmission and transparency, but the results are the same.
How do I fix this?
I have also attached 2 samples of real beveled glass. Keep in mind the glass my client is using is not tinted. It is as clear as he could get it.
I have attached a blend file here. One is a diamond like edge cut, one is a flat extruded plane, and one is a pane of glass with a bevel modifier with subsurface and smooth shading.
I have had a look at your blend and cannot see anything inherently wrong with what you are doing (aside from your top pane of glass being unnecessarily subdivided).
I created a clean scene from the Blender startup - added a plane, extruded it and applied the Glass shader and added an environment HDRI - and I get the same banding as you observe. I checked my normals etc and everything was fine.
The only way I have found to get rid of it is to add a slight amount of roughness to the glass (say 0.005) - but then this means your glass is not quite crystal clear. Give it a try and see if it’s an acceptable solution.
Perhaps cycles glass shader may not like thin refractive objects viewed edge on.
Thank you for looking into it. I am sad that blender doesn’t appear to handle it well. My clients object is basically a terrarium made out of those separate panes of glass bound together.
If anyone comes up with a better solution, I would appreciate it very much!
I think moony was quite right in the post #4. Those chanfered edges are normally not so smooth as the tempered faces of the glass. This makes a big difference!
So you need to have two materials, or use vertex paint to drive the roughness on those faces.
Another thing that has special importance in glass, is absorption. Specially when we are viewing at those faces, light rays travel a long distance inside the glass, either going to the other end, but mostly bouncing inside the glass until hitting a point where there’s no total internal reflection.
edited: there’s also the possibility to turn the shader into transparent after a number of bounces…
here’s an example http://www.pasteall.org/blend/41689
Yes adding a second material for the edges of the glass with a higher roughness did seem to fix the problems for the shots I am working on! Clear large surfaces with the edges rougher seems to be working. Thank you very much for helping me out!
