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After Effects Motion Tracker – Placing Items in the Background
Okay, so my issue is this. I have a clip from a movie that I am finishing. In the background is a computer screen. It has nothing on it (was filmed with the monitor off) and the arms and other objects of the actors in the scene pass in front of it. I have tried using the motion tracker but as my skills are still at a minimum I can’t figure out how to get the new computer screen graphic to track along with the shot and not lay over the arms and objects moving in front of the monitor. Also, I can’t get a clean track as when the arms move in front the tracker points skew. When i try to go back and adjust each frame, the target layer skews off of the one corner of the screen.
Any ideas? or am I forced to rotoscope the image in frame by frame?
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2 Replies
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Sorry to say, but you’ll have to roto out the arms as they pass in front. And you can do motion tracking, but you’ll have to manually adjust the points when something gets in the way of the track. It’ll be a lot of work, but it can be done with a lot of time and patience. Of course there’s better tracking programs out there, but for just using AE, that’s the only advice I can give.
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Remember you don’t have to track specifically on the monitor. You can track on anything in the scene that moves the same as the monitor, even objects that are not affected by the arms.
For track points that are partially obscured over the duration of the scene, you should check out Andrew Kramer’s set extensions tutorial at videocopilot.net to see how to do a tracker from multiple tracker points using null objects.
Get comfortable with Null objects and parenting. It might seem overly technical at first but nulls are very powerful for tons and tons of reasons, not the least of which is motion tracking.
Also, if you use the corner pin tool, the same thing applies. You can put the tracker in one position, but the actual corner node elsewhere relative to it. Obviously you want a stationary camera POSITION but you should be able to pull it off.
Brian
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