Ambient Occlusion Shadows flickering

Hello. Can anyone tell me why the shadows are flickering during a fast camera move? Here is the movie:

https://vimeo.com/38356249

It is the opening camera move. The AO Shadows flicker during the move. All is fine after. I am rendering a motion (Vector) blur through the compositor. I think that may be at fault but haven’t had time to test it yet.

Any other ideas?

Thanks, Chris

I don’t know why this is happening but if you don’t find a solution, I’d slow it all down, re-render and then retime it back to the faster movement it in post. Doing it like that, though, you can’t use motion vectors to create the motion blur but need something like AE’s CC Motion Blur and kinda fake it…

Of course it’s better to find the real problem and solve it in Blender, but if you’re in a hurry, this is a quick solution. :slight_smile:

Not a bad idea. I had a similar issue with text flickering in a different shot. I finally killed the motion blur and it was fine. Frustrating!

Thanks, Chris

OK. Fixed it! On the Vector Blur node is a setting for Speed. There is a “Min” and a “Max” that you can set. By default they are set to Zero. I changed “Min” to 5 and “Max” to 20. I get decent motion blur and no weird artifacting.

I can’t tell you exactly what the values do (other than the vague description when you hover the mouse over them), but a little playing should help!

C

Nice that you solved it, if for nothing else it might help others running into the same issue. :smiley: