Using Houdini Indie 20.5.278
Windows 11 64GB Ram
Ryzen 9 3900X 12 Core
nVidia 2080RTX


Hi,

I'm encountering an issue and I'm unsure if it's a bug, an expected behavior, or something I can adjust.

I'm working on a car model where the front lights consist of multiple layers of glass. When rendering with Karma CPU, I achieve the desired result. However, when I switch to Karma XPU, the outcome differs specifically in this area. The issue arises when I add a second glass layer on top of the first. The Shader was done with materialX( transmission and transmission color)

Is this normal behavior for XPU, or is it a bug? Any advice would be appreciated.

Thanks!

Just guessing here but have you tried adjusting the Ray Bias? In the past I've seen some artifacting with transmissive geo overlapping other geo and lowering the ray bias solved it for me.

The geo are not overlaping but anyway I tried to change Ray Bias value but nothing changed.

The geo on the back (orange) get an normal map on it and the issues seems to be the way the light reflect on the second glass bump. They reflect differently.

Is it possible you could reduce the scene down to the most simplistic elements which demonstrate the issue, and then file a bug?
thanks