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Tracking: null object jumping around

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Ron Dangus
Tracking: null object jumping around
on May 21, 2013 at 11:13:08 am


Although I've been using AE for a couple of years, I mostly use it for color correction. I've got some footage with the audioboom in sight.

I have a couple of frames with no boom, so I thought I'd copy those, mask the needed area, freezeframe it, and then apply it to my footage. Since it's 2,5 seconds of footage, and I don't want to do it frame per frame, I wanted to do it with tracking and a null object.

I've tried to track my footage with the standard AE tracker. I've tried parallel corner pin, perspective, the normal one, .. Everytime I apply the tracking data to the null object, it just jumps around.

I can't track the square I wanna replace, cause it's going in and out of the frame, and the boom getting into the image messes up the tracking points (even when I replace them by hand frame by frame), so I tracked other points in the footage. As you can see, there are a lot of high contrast spots easily trackable.

Can someone tell me what I'm doing wrong?

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John Cuevas
Re: Tracking: null object jumping around
on May 21, 2013 at 11:38:45 am

Not really enough info, but have your tried enlarging your tracking area and search area.

Another option would be to use the 3D camera tracker, attach a null to one of the tracked points and attach your clean footage to that.
Also, have you tried to use Mocha for AE to track your object, or an object in the scene?

Here's a couple of tutorials on motion tracking that might also help you out:

Motion Tracking Part 1

Motion Tracking part 2

Johnny Cuevas, Editor

"I have not failed 700 times. I have succeeded in proving that those 700 ways will not work. When I have eliminated the ways that will not work, I will find the way that will work."
---THOMAS EDISON on inventing the light bulb.

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Ron Dangus
Re: Tracking: null object jumping around
on May 21, 2013 at 10:41:09 pm

John, thanks for your reply. I found my mistake: I motion stabilized using Mercalli as a plug-in, forgetting that the tracking was done on the original footage. That's the reason the null object was jumping around while my footage wasn't.

I precomposed the footage, tracked and masked onto the original stuff, and then applied Mercalli to the new, masked precomp.

That way it looks perfect

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