At the moment I'm trying to render another animation very similar to my "...and yet another sci fi scene..." scene, which was rendered with the path tracer as well.
I adjusted some shaders, moved the objects a bit, and animated the camera differently. There is no atmosphere involved, and the lighting I used is not much different from my previous scene.
In my first tests of the actual animation I encountered some really heavy flickering. There was no flicker at all in the other one. I created a GI cache file, but the flickering was still there. This is really weird.
So here is my question: are there any other reasons for GI flicker using the path tracer? I know, that if clouds are in the scene it might be a problem, but there's nothing.
OK, I might have solved the problem on my own. In the new scene I added some sort of neon tubes at the ceiling. I duplicated the tubes and gave the first set a luminosity of 6 to illuminate the interior. Since it looks weird to have a visible object with such a high luminosity I set it to invisible, and made the other one visible, but with a luminosity of 1. So I guess these two objects interferred with each other somehow, since they are at the exact same location, which was causing the problem I guess. So I unchecked the visible tubes' "visible to other rays". Seems to be working now. And fortunately the path tracer is not to blame...
Good that you found it!
Indeed! Things like that can drive you crazy, when you think the problem is something different.
I always scaled down my light emission objects just a hair so their meshes weren't intersecting. May also fix the issue without any other rendering tweaking.
Good idea!