Could somebody please explain this render artefact?


Today I went back to a model to tweak the materials. I added HDRI lighting. I’m seeing strange artefacts on the wheel on the left. There are very obvious sharp edges for some reason (Circled in the picture below). I’ve also included screen shots of the material node set-up as well as the world node set-up. I’ve tried two HDR images with the same results. If I look at the model front on, the hard edges are pretty much perfectly at 90 degrees going around the wheel. Any clues as to what might be happening here?

It seems to be something to do with the UV seems. As I move the seems and un-wrap again, those hard edges move. Is this normal? Even though, other than the normal map, I’m not using any image textures for the wheel?

Some information not supplied

What about the mesh itself, check it is correct with no problems
Any modifiers (mirror modifier etc) ? Are settings correct ?
You are using a normal map. Do those harsh edges coincide with the seams on the UV map ?

Hey Richard,

All modifiers have been applied. The mesh is pretty clean. After experimenting moving the seams and re-unwrapping, I can confirm that the harsh edges follow the seams.

EDIT: Also, if I completely remove the normal map, the problem completely disappears.

I found the problem. I had moved the folders about recently and so the normal image wasn’t actually open in Blender.