Mirror artefacts
Posted: Wed Jan 02, 2019 6:29 pm
While setting up some scene, I came across a strange behaviour with a mirror and Sky-background. Looking somewhat perpendicular at a mirror gives me the following type of artefact:
Blend file attached, consisting of a clean setup of only a mirror and camera, the rest is left pretty much default.
Here is what I can say so far from quick playing around with it:
- happens with all bidir/path + /sobol/MLT/Random combinations
- The artifact is half the size using BiDir than using path
- It can be different between preview and actual render
- Mirror and Glossy material behave the same
- The pattern heavily depens on the camera-mirror distance
- The pattern heavily depends on clipping start, but not clipping stop
- camera FL changes nothing other than zooming in on it
- Using volumes or not makes no difference
- The pattern changes with orientation of the camera/mirror pair. It then appears to be partly cut off (by what??). You can test this by selecting camera+mirror and rotating them around the origin.
What I haven't tested a lot yet is various light sources, i.e. if this only an issue with the background sky.
Blend file attached, consisting of a clean setup of only a mirror and camera, the rest is left pretty much default.
Here is what I can say so far from quick playing around with it:
- happens with all bidir/path + /sobol/MLT/Random combinations
- The artifact is half the size using BiDir than using path
- It can be different between preview and actual render
- Mirror and Glossy material behave the same
- The pattern heavily depens on the camera-mirror distance
- The pattern heavily depends on clipping start, but not clipping stop
- camera FL changes nothing other than zooming in on it
- Using volumes or not makes no difference
- The pattern changes with orientation of the camera/mirror pair. It then appears to be partly cut off (by what??). You can test this by selecting camera+mirror and rotating them around the origin.
What I haven't tested a lot yet is various light sources, i.e. if this only an issue with the background sky.