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Subject needs to be close to green screen..

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Yianni Papanicolaou
Subject needs to be close to green screen..
on Mar 4, 2010 at 7:35:36 am


I'm about to shoot some green screen footage with the objective of pulling a key of just the actors arms. The arms will then be composited to give the illusion of coming from behind a large building and interacting with parts of the front of it. I've had to pull many keys in the past with the subject placed at a suitable distance from the screen and had no problems. Now, the arms are going to have to be in front of a large background green screen and also in front of a smaller screen to key out the body, right? My main concern is that the arms are going to have to be quite close to this second screen and I imagine shadows and spill will be a problem. I need the final result to look like the building is the torso with multiple sets of arms that come from the side at various elevations and touch various places on the buildings front.

I would also like some shadows cast on the building from the arms, I'm invisaging using a copy of the arms blacked out and blurred with a radial blur with the source point placed real high and maybe a simple feathered drop shadow from the original arms and animate both to reduce the distance of the cast shadow as the hands touch the building but I imagine this will looka bit dodgy. Any suggestions?

We are shooting on PAL HDV 1080p 25fps and compositing in AE CS4 with Keylight on a quad-core mac with 12gb ram

Thanks in advance for any assistance offered, sorry for the long post..

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Steve Roberts
Re: Subject needs to be close to green screen..
on Mar 4, 2010 at 1:43:13 pm

You could wrap a green fabric around the talent's torso.
Or use the second "body" greenscreen on a sandwich board and use the shadows on it as shadows for the building ...?
Hey, do a test.

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Michael Szalapski
Re: Subject needs to be close to green screen..
on Mar 4, 2010 at 2:21:03 pm

He's shooting HDV; that's probably going to make it very difficult to get a nice shadow to use on the building from the shadows on the green, but it's definitely worth a try. CERTAINLY worth a test.
You might try hanging a light almost directly above the talent. Try to get a bit of backlight on the arms. It will help it look more like it's lit from above by the sun and may help you with shadow issues.

Yianni, do you have the equipment to capture the uncompressed signal from your camera, rather than pulling it off of a tape or memory card later? Many cameras have an output that can be put through a video capture card. That way you avoid the terrible color resolution of HDV footage. If you don't know what I'm talking about, this might be useful.

- 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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Illya Laney
Re: Subject needs to be close to green screen..
on Mar 5, 2010 at 4:40:18 am

Spill and shadows are not a problem if you know what you're doing and can roto well. Keylight corrects spill already so don't worry about that, just use soft or hard color to adjust the spill...Or you could throw on an extra grade after the key to desaturate the greens. I'd suggest using Primatte because of it's superior spill suppression rather than Keylight or just use Nuke's IBK and be done with it. After all that and a light wrap, you really shouldn't notice anything.

***Here's a good tip if you bring a Mac on set with you.*** Hook the camera up to a Mac and record the video through the Quicktime Pro Application uncompressed via Firewire. It takes up a crazy amount of space but I've gotten better results doing that with my sh*tty HV20 than shooting straight to tape. I found that out after attempting to use the HV20 as a Webcam. Haha.

Motion Design, Color, Editing
Simulated Wood Grain Cabinet Inc.
Bunim-Murray Productions

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