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Dynamic mask?
Chances are.. this is a stupid, moot question – something I should have been able to discover on my own. Sadly, I’m unintelligent. Plus I haven’t really had too much luck with Google. So here goes.
So I know what masking does, and I comprehend its standard method of implementation. You have somebody’s face in the video, say. You draw a face-shaped bubble around that face. You finetune it. You move around in the timeline and make painstaking adjustments to the shape of the bubble, based on alterations to the face’s shape in the video.
It seems to me that any program which can be told to track motion in a video should also be able to figure out what a person is attempting to mask, and process a sort of dynamically computated mask across a timeline range, based on the user’s initial (and perhaps end-of-timeline) mask. Or, if AE itself doesn’t have this capacity, then a plugin probably exists.
So that’s what I’m after. Either the correct step within AE itself, or the plugin or plugins which attempt to fill this gap. Because right now, the painstaking nature of mask finetuning is one of the biggest timesinks in anything I’ve attempted so far.
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2 Replies
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Welcome to the world of roto-scoping. There is no plug-in or feature that does what you want automatically. There are techniques to speed up the manual process it is still manual.
I don’t have to do it very often but when I do I usually adjust the mask every 5 or 10 frames, then go back to see if After Effects tweens the make correctly in between, if not I had more keyframes.
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Yes, rotoscoping is time-consuming. Check out the options ($) by Imagineer systems: Mocha etc.
Within AE, the idea is to study the motion, then create a key for the mask shape when the shape-changing changes direction, or is at a point of inflection. For example, if something gets bigger, then smaller, add a key when it stops growing and starts shrinking. Let AE do the interpolation between. Don’t set keys at a regular interval unless the motion specifically requires it.
Also, separate a complex shape into its non-changing elements, if you can. If the thing has five elements that change position, that’s easier: you just move the masks, rather than having to aniamte the shape of one.
Of course, if the shape is organic, like a flowing cape, you probably have to do that frame-by-frame. Try switching rotobezier on for that one.
Note that when rotating a mask, AE makes the mask vertices travel in a straight line between keys.
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