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Need ideas on how to stabilize this footage

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Dennis Bodin
Need ideas on how to stabilize this footage
on Jan 10, 2010 at 5:53:26 am

Hi all:


I have this footage when a cameraman walked around the stationary guy in the middle, doing some sort of a 360 shot around him. I need to stabilize this footage, making the guy apprear spinning around the red axis in this diagram:
http://i150.photobucket.com/albums/s99/dc2000_bucket/roto.jpg

Can you recommend a tracking method/plug-in to do this before I begin?

Thank you in advance!


PS. Later on I will also have to rotoscope him out.


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Dave LaRonde
Re: Need ideas on how to stabilize this footage
on Jan 11, 2010 at 3:43:31 pm

[Dennis Bodin] "...making the guy apprear spinning around the red axis in this diagram:"

If the camera didn't revolve around that red axis, you can't magically put him on that axis.

------------------------------------------------------------------------------

[Dennis Bodin] "...Can you recommend a tracking method/plug-in to do this..."

Nope. You'll need to re-shoot.

Dave's Stock Answer #2:

When you're out on a shoot, and you say, "we'll fix this in post" without knowing PRECISELY HOW you're going to fix it in post, don't shoot it! You'll only end up shooting it over again.

Since post typically costs three times the cost of production, fixing something in post is not a way to save money, but rather a way to spend more of it.

And, before you say "well fix it in post," always consider who's doing the work, especially if you're the one doing the editing.

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[Dennis Bodin] "PS. Later on I will also have to rotoscope him out. "

When you re-shoot, consider putting the guy on a turntable. If your camera is up to the task, you may also want to consider shooting against a chroma key background.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Dave LaRonde
Re: Need ideas on how to stabilize this footage
on Jan 11, 2010 at 6:28:14 pm

On a second look at those three frames you posted, I see yet another problem. As the camera revolves around the subject, the lighting changes.

Since your goal is to put this guy over a different background, no one will know why the lighting is changing on him, and it will look god-awful.

So there's another argument for re-shooting. This time, it would help to plan out the shot.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Dennis Bodin
Re: Need ideas on how to stabilize this footage
on Jan 13, 2010 at 7:23:01 am

I appreciate your input guys! But let's face it that if I used a chroma key background, a turn-table for the guy, a steady light source and a camera on a tripod I wouldn't be here asking these questions, would I? Reshooting it is not an option so I had to deal with whatever footage I have at the moment.

I also tried tracking like Michael suggested but the problem became apparent right off the getgo. Since those track points were off the rotation center the final result looked like the guy was wandering to the side, which was not satisfactory. But..... I did it with another method.

I looked at the footage and to my amazement I realized that we shot it on an almost gridded background (see those stone tiles) and that I can use them to find the bottom anchor point for 3D rotation. Take a look at this screenshot:

http://i150.photobucket.com/albums/s99/dc2000_bucket/stabilize_1_guy.jpg

I had to track two bottom yellow lines (that match two perpendicular cracks in the ground) and used expressions and geometry to find their intersection that gave me the bottom stationary point for this 3D rotation (red dot in the screenshot.)

The second stationary point became the top of the guy's head, which was somewhat easy to track with a built-in AE tracker (the top red dot).

And that was it! Using both dots (or expressions for them) as two track points for stabilization I was able to make this footage stable. Of course, there's still Dave's point about lighting, but I hope to smooth it out with keyframed curves and levels. So we'll see. Another technique that I'm banking on is that I will be able to significantly speed it up in the final project. As I said this is an approx. 30 second video, so there's lots of information to make it look nice in an 8 second (or even maybe 5 second) spin. It took me some time to fix it but it was worth it!


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Steve Roberts
Re: Need ideas on how to stabilize this footage
on Jan 13, 2010 at 7:24:38 pm

That should work. Clever!

In the "next time you shoot this" sweepstakes, consider a greenscreen on a rolling frame, moving directly opposite the camera. This way you'd only have to roto out the feet and lower legs.

It does commit you to losing the background, though. The client can't change his mind if he decides he actually likes the background. :-)



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Dave LaRonde
Re: Need ideas on how to stabilize this footage
on Jan 13, 2010 at 9:58:32 pm

[Dennis Bodin] "It took me some time to fix it but it was worth it!"

Yipes! That's a lot of work! But I have to admit, you pulled it off and I didn't think you could. Good luck getting the lighting to work out.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Michael Szalapski
Re: Need ideas on how to stabilize this footage
on Jan 11, 2010 at 5:11:02 pm

Without seeing the camera's motion, it's hard to see what issues there are. I'm guessing that there's no dolly track - that it's handheld. Since you're just now asking how to fix the shot, rather then thinking it out ahead of time, it indicates that there was no planning in place.
So I'm guessing the camera guy probably gets closer and further from the guy in addition to tilting and bouncing. This, coupled with the fact that you're doing a 360 means you're going to have a difficult job.
For future reference:
Since you're going to be rotoscoping him out, you could have put the camera on a tripod, the guy on a turntable (or lazy susan-type thing) and spun the guy. (Maybe even in front of a chroma screen; might have saved you some rotoscoping trouble).

It may be easier to use some third party stabilization plug-in...

Again, without seeing the actual footage it's hard to know how to deal with it. You might have to do it in pieces, a bit at a time and possibly some frame-by-frame tweaking yourself by hand.

Using AE's built-in tracker, I would track a point on the ground by his feet to stabilize. I'd do it for as many frames as I could get away with, then appy it, choose a new spot and do it again.
Or, when that didn't work, I would just go frame by frame through the footage in the tracker, making sure the tracker point is in the right spot on each frame. You may need to do some smoothing and tweaking after, but that might start you off on the right way.

- The Great Szalam
(The 'Great' stands for 'Not So Great, in fact, Extremely Humble')

No trees were harmed in the creation of this message, but several thousand electrons were mildly inconvenienced.


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