Blackmagic Forum

Does anyone have any ideas what the cause of this glitch is? It happens at seemingly random points of the video I'm working on. When I've had these issues in the past, enabling 'Flatten Transform' on Merge nodes with masks has helped, but that doesn't seem to be fixing it this time.



The glitches tend to appear as 1-frame artifacts — sometimes strobing, other times at random intervals or over a number of frames. In Fusion, the example shown below appears as checkered grey & black artifact (as if it's transparent), but they appear white in the final render (there's no alpha channel option when rendering. Presumably they'd be transparent there too if there were).

The glitches don't appear in the timeline when working in Proxy mode (haven't checked if they appear when not working in Proxy mode yet). The final video export is rendering in ProRes 422, 60fps, 4k.

Are you using any 3D in the scene? It might be z-fighting—two 3d objects sharing the same, or nearly the same coordinates, and the renderer sometimes miscalculates which one should be in front. If that's the case, it can frequently be solved by increasing the scale of the scene using a Transform3D tool right before the Renderer3D. If you have any lights in the scene or have turned on Depth of Field, those parameters will need to be adjusted after a scene scale, but if not, everything should render exactly the same.

If it's not a 3d problem, then I'm not sure what the issue might be. Have you tried rendering to an image sequence to verify it's not an encoder issue?

z-fighting, what a great name Bryan. Maybe we should call it Z-depth figthing, and make a song about it?

Every layer was Z-depth fighting!

No 3D elements in this project sadly. I agree, it does look like the type of thing you get when you layer multiple 3D elements on top of each other at the same Z-depth.