I have an issue with my glass window that create some weird effects in Vray. I tried a few different material, try take away the thickness of the window, different light settings, but this weird effect remains. I’m sure there’s an explanation and something to do about it, I’m just not able to find it.
I’m not sure exactly why you’ve set up your window/background image the way you have it. It looks like this is a ‘Z-Fighting’ issue where you have two planes sharing the same surface.
I found that the issue of the glass weird effect was coming from the thickness of the object. So I replace the window by a single surface. It works now. Though I need to find the right setting for the reflection.