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Green Screen Footage with no Motion Trackers

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Jason Matos
Green Screen Footage with no Motion Trackers
on Apr 28, 2011 at 7:46:18 pm

So. I have just shot my first music video on a green screen cove.

Both my VFX artist and I completely blanked out (COMPLETELY) and did not place motion trackers on the green screen.

Our cameras don't have TONS of movement but there is enough to make the genie looking floating effect when we put them onto a background.

Now, our backgrounds are simply colored vignetted backgrounds, nothing crazy complicated like a cityscape or a forest.

SO, my question is:

Is there a way to do some basic motion tracking without the physical markers on the green screen? Any solutions?

ANY help/hints/thoughts are appreciated.


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Dave LaRonde
Re: Green Screen Footage with no Motion Trackers
on Apr 28, 2011 at 8:15:17 pm

If there isn't anything in the shot you can track -- a light stand you masked out, for example -- you're stuck doing it by hand. Sorry.

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


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Jason Matos
Re: Green Screen Footage with no Motion Trackers
on Apr 28, 2011 at 8:23:21 pm

Thanks for the quick response Dave.

Would you be able to direct me to a tutorial or simply lay out a few directions on how to motion track my hand?

Is there an accurate (maybe not as accurate as motion trackers) but close to accurate way of doing it by hand? Again, any assistance is greatly appreciated!

Thanks!


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Dave LaRonde
Re: Green Screen Footage with no Motion Trackers
on Apr 28, 2011 at 8:53:37 pm

You don't really motion track: you animate the background's Position or Anchor Point properties (take your choice) by hand. There's no actual tutorial for it. There's no semi-automatic way to do it. It's grunt work: a right royal pain-in-the-neck process that takes time & patience.

But get to know your keyframes and Keyframe INTERPOLATION (aka how they affect motion):
http://help.adobe.com/en_US/aftereffects/cs/using/WS3878526689cb91655866c11...
http://help.adobe.com/en_US/aftereffects/cs/using/WS3878526689cb91655866c11...

Make sure your background is bigger than your comp. That way, you won't run out of background when you have to move it. How much bigger does it have to be? That depends on the motion in your chroma key shot. Personally, I'd use a stand-in when animating: a nested comp that you THINK will be big enough. Apply the Grid Effect to a solid in the nested comp to gauge motion more accurately.

Look on the bright side: when you're done, you'll never, EVER forget track marks.

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


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Jason Matos
Re: Green Screen Footage with no Motion Trackers
on Apr 28, 2011 at 9:08:58 pm

Excellent, thank-you for your much needed assistance Dave! You've been a great help, I had a hunch that there was a way to fix it.


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Walter Soyka
Re: Green Screen Footage with no Motion Trackers
on Apr 28, 2011 at 8:51:44 pm

[Dave LaRonde] "If there isn't anything in the shot you can track -- a light stand you masked out, for example -- you're stuck doing it by hand. Sorry."

Wow -- this might be a rare case where a wrinkle or mark on the chroma key background could actually help.

Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog - What I'm thinking when my workstation's thinking
Creative Cow Forum Host: Live & Stage Events


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Dave LaRonde
Re: Green Screen Footage with no Motion Trackers
on Apr 28, 2011 at 9:06:39 pm

Very true, but that's a lot to ask. I hope for the guy's sake those inadvertent marks are actually there.

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


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Jason Matos
Re: Green Screen Footage with no Motion Trackers
on Apr 28, 2011 at 9:28:44 pm

Negative, the cove was freshly painted :P

But, if there were marks, would AE tracking still pick it up?


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Tudor "Ted" Jelescu
Re: Green Screen Footage with no Motion Trackers
on Apr 28, 2011 at 9:39:04 pm

I would give Camera Tracker from the Foundry a shot. If there's anything in the shot that can be used this one will pick it and use it for a camera solve.

Tudor "Ted" Jelescu
Senior VFX Artist


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Dave LaRonde
Re: Green Screen Footage with no Motion Trackers
on Apr 28, 2011 at 9:40:53 pm

[Jason Matos] "would AE tracking still pick it up?"

Maybe yes, maybe no. It would be a crap shoot at best.
And you'd have to mask out the marks to get a clean key.
And if those marks happened to pass behind the subject, the track would go south on you and you'd have to do rotoscoping work to boot.

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


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Jason Matos
Re: Green Screen Footage with no Motion Trackers
on Apr 28, 2011 at 10:09:00 pm

Looks like I'm sticking with manually moving the background layer - thanks all!


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Chris Buttacoli
Re: Green Screen Footage with no Motion Trackers
on Apr 29, 2011 at 3:03:17 pm

Still, any marks or bumps, or anything barely visible on the wall will make hand tracking a lot easier. So look carefully for one. My fingers are crossed for you.


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Dave LaRonde
Re: Green Screen Footage with no Motion Trackers
on Apr 29, 2011 at 3:16:21 pm

...and here's another thought: there may be stationary objects in the shot you can track, too.

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


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