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how do i keep a moving object in the centre of the frame

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Steve Harvey
how do i keep a moving object in the centre of the frame
on Dec 17, 2015 at 6:26:45 am

Hi, I film a lot of presenters in the production of training videos, as part of the production we drop in the PowerPoint slide so have to keep the presenter in the centre of the left hand segment of the frame. Most presenters seem to think that the more they walk about on stage the cooler it makes them look to the audience, unfortunately from my point of view I have to manually centre them every couple of frames and keep them there with key frames.
I have tried motion tracking in after effects but even though I have a very high powered work station with lots of ram and processing power it can take 3 days to track the points in motion tracker, does anyone have a simpler solution please???


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Kalle Kannisto
Re: how do i keep a moving object in the centre of the frame
on Dec 17, 2015 at 8:01:09 am

I would tell the presenter not to move around.

If that is not possible for some reason, give them a "tracking point" such as a white tie pin that is easily tracked with a point tracker and use that one point to track and stabilize the footage horizontally with a smooth expression.

(You said "tracking the points" which makes me think you are using something else than a single point to track. Tracking a single point should be way faster.)


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Steve Harvey
Re: how do i keep a moving object in the centre of the frame
on Dec 17, 2015 at 11:32:50 am

Hi Thanks for the response, I meant tracking point. typically we use a lapel mic although for some reason although we provide a 45" comfort monitor theses people cannot resist looking at the main screen, presumably to see if its still there, and in so doing we loose the track point. Oh and by the way I enjoyed your joke about asking them not to move around! As I said previously My work station seems to take an age to track the point and I thought that the problem was with my settings, I was hoping someone may point me in the direction of "Motion tracking for Dummeys"


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Kalle Kannisto
Re: how do i keep a moving object in the centre of the frame
on Dec 17, 2015 at 12:10:28 pm

Ok then. There are a whole bunch of factors that determine the speed of tracking, not the least of which is the computer you are using, and obviously the length of the footage. But one important thing is you want to have as small a tracking target and, even more importantly a small search area, the latter just large enough to account for the largest motion from one one frame to the next. That's where most of the processing power goes, searching through those pixels, so you don't want any extra there.

Then you could consider alternate strategies. It is not necessarily a good thing that the camera is moving constantly, so using you manual method to to re-position the footage but only doing it when it is absolutely necessary might even be faster than tracking the shot.

Alternate strategy #2: Shrink the footage so that it fits completely in that half of the screen, then take occasional close-up views when the person is not moving. Maybe there is a reason you could do this, such as showing other visuals in the "extra" space that you will create.


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Dave LaRonde
Re: how do i keep a moving object in the centre of the frame
on Dec 17, 2015 at 4:35:55 pm

Mmmmm.... doesn't it look kind of odd when the presenter takes steps but doesn't move?

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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Kalle Kannisto
Re: how do i keep a moving object in the centre of the frame
on Dec 17, 2015 at 6:34:06 pm

"doesn't it look kind of odd when the presenter takes steps but doesn't move?"

Yes, then there is that. Stabilizing the shot too perfectly on the person will give a similar effect to GoPro footage where the camera is attached to something, wherein the "something" (in this case, the person) looks static while the background moves in a dizzying fashion.


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