Green Screen problems

L

LeavingTheCandy

Well-known member
I have a green screen shoot that had an error that we didn't see 'til post.
Attached is a small closeup segment of the screen. There's a black strip along the side of the green that does not belong there.
The catch is that the shot pans so an easy mask fix is not an easy fix (it changes perspective). Any ideas?

PastedGraphic-5.png


Thanks.
 
You might be able to use a color key/luminance key effect (maybe with a mask on just the area with the black) to just key out the black. Depends on what is in front of the black area in the shot.

If you must isolate it, track it with mocha and use the corner pinning feature. It should be able to handle the pan and perspective change. You might need to hand adjust the pinning but you should be able to get a mask(apply the corner pin to a solid). Combine that with a lumiance key and you should be pretty close.

That reflection on the desk is going to give you some headaches too. Mocha might be able to track that desktop and let you handle that reflection seperately by masking that surface off.
 
Thanks for the ideas. Yes, all kinds of problems....the desk too. It keys ok, but there's a lot of noise that is causing it to act funky.
I tried the luma-mask to get rid of it and there's too much stuff in front of the green that gets lost.
I have not really used Mocha much. I guess my time has come.

I was considering a roto in Photoshop too. Any other ideas?
Thanks.
 
One thing that might help you is the free Unmult plugin (it's available at Red Giant Software). It's primary use is to create a matte for things shot on black. I mainly use it on old explosion stock footage. It's also useful on lens flare images (where the flare is rendered on black). It might be able to help you with the luma key.

When using AE you have to sometimes think more like Nuke/Shake/Fusion. You want to build up a set of comps that when combined together get the end result you want. Which means you might create the mask for the black area using a bunch of different methods, each adding a bit more to what will become the final mask. A close luma key + a few hand made and tracked roto shapes (to fill back foreground areas) might do the trick. Worst case though you may very well have to hand roto a lot of the shot. Depends on the footage, the length of the shot(s), etc.
 
Its got a pretty clean edge. Do you have CS5? This is where the roto brush works a treat.
 
I do have CS5, but am not aware of the Rotobrush. How does it work?
In the meantime, I've had some good success using Mocha to track the move and create a shape matte. Seems like it's gonna work.
Haven't used Mocha much but it ROCKS!
 
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