Octane Glass Material Problem

Fri Jun 12, 2020 6:57 pm

Hi, i was wondering if anyone has encountered this issue with lines on the glass surface when using path tracing to render glass objects.
I cant seem to solve it, I've tried various methods.
I've checked that i have specular depth set at 32, no intersecting geometry or reversed normals also tried subdividing it as well.
Also tried increasing Ray epsilon as well. Wanted to check if it was a scene/lighting problem so i exported the cup into an empty scene and it still has this issue,
however this issue is gone when i switch to Direct Lighting. I am currently using Octane 2020.1 version.

Beppe OctaneRender™ Italia Blue Sky · Mon Jun 15, 2020 8:51 am

Hi,
does it happen also with a white backdrop/environment?
You could use the InfoChannel passes to check the geometry/shading/vertex normals.

ciao Beppe

Mon Jun 15, 2020 8:58 pm

which lines are you referring to in your render? those repeated lines at the base?

Tue Jun 16, 2020 4:10 pm

I think what you are seeing is physically correct. Yes, it will look different in direct lighting, because the rays are not being refracted back and forth within the glass in the same way.

This is what I get in a similar setup, and is what I expect to see.

Tue Jun 16, 2020 5:02 pm

Yeah those lines at the base is how a glass like this refracts in real life. I found some photos of this the other day-I’ll post when I’m back at my computer

Tue Jun 16, 2020 6:37 pm

It's funny how that works out sometimes, when our expectations are out of sync with what's actually more realistic. I had a funny debate about how motion blur works in real life with someone who insisted it should only be behind a moving object, not in front.

Tue Jun 16, 2020 7:03 pm

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frankmci wrote:It's funny how that works out sometimes, when our expectations are out of sync with what's actually more realistic. I had a funny debate about how motion blur works in real life with someone who insisted it should only be behind a moving object, not in front.

The amount of times I've had a client say "X part of the render looks like weird" and then I tell them "no that's how it looks in real life" with an attached reference photos--at which point they're all like "ok, cool, it's fine then"

Here's one of the refs I mentioned. I couldn't find the exact same glass but you can definitely start to see it happen in the tapered part.