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Artifacts When Using CC Force Motion Blur/Blending/Timewarp on PNG Sequence
I often work with png sequences exported from Blender and imported in to After Effects. In the past I’ve often noticed that when adding “CC Force Motion Blur” to the sequence and then turn on “Frame Blending” I’ll get strange artifacts appearing around the object. The best way to describe it is that the edges of the 3d objects appear like they would as if looking at them through a heat wave or thick glass. Very annoying and I’ve just learned to work around it and add a directional blur as opposed to the motion blur effect. Well, recently I’ve noticed it happening when I use timewarp and I figure there’s got to be an explanation. The sequence is just a simple set of pngs rendered out of Blender 2.6. I usually notice it when I add a lot of specularity to the objects, but I’ve sometimes noticed it even when there’s none. Not sure if it’s a problem with the way I render the sequence out of Blender or if it’s After Effects or whatever. Any help is appreciated. Many thanks.
Jason
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3 Replies
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Its common issue, u can only turn to the max error treshold and block size @ timewarp effect, artifacts should be reduced.
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cc force motion blur isn’t really designed to add motion blur to footage, it’s designed to add motion blur to effects that don’t support ae’s native motion blur…. there’s a pretty big difference in how that works.
timewarp can add motion blur when that’s enabled in the effect, but the algorithms used are so-so and results can be hit or miss.
if you do this type of work often, you might check out reelsmart motion blur (revisionfx.com). it works quite well, and if you can render out motion vectors from your 3d app, it works even better.
here’s a tutorial that covers using rsmb:
https://aloedesign.com/2008/12/maya-2d-motion-vectors-tutorial/
Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW -
Thanks Michal and Kevin. Michal – I got your suggestion to work. Turned up “Error Threshold” all the way and then turned down “Block Size” and then also checked “Build From One Image” and it reduced the artifacts quite a bit.
Kevin – thanks for the explanation on the motion blur. I have heard a little of reelsmart and I’ll have to check it out and see if I can get a better result and also see if I can render out a motion vector out of Blender.
Thanks Again for the help.
Jason
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