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Make an artificial green screen [ANSWER]

Posted: Tue, 17th Jul 2007, 7:27pm

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Defcorpse

Force: 600 | Joined: 28th Apr 2007 | Posts: 7

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I was wondering if you can take a shot with an actor and a clean plate. And set them on top of each other. And change the compisite to difference and some how make an artificail green screen.

What i am basicly saying is can you seperate and actor from its background using a clean plate.

Sorry if I making it hard to explain.
Posted: Tue, 17th Jul 2007, 7:43pm

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Axeman

Force: 17995 | Joined: 20th Jan 2002 | Posts: 6124

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SuperUser

Separating an actor from the background without keying requires a lot of time-consuming masking. In general, the whole point of a greenscreen is to make this very labor and time-intensive process much easier and quicker.

There are technologies being developed that do make background removal without a greenscreen easier, but if you are working with CompositeLab, greenscreen is the way to go.
Posted: Wed, 18th Jul 2007, 5:31am

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Defcorpse

Force: 600 | Joined: 28th Apr 2007 | Posts: 7

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Ok, I just saw a video of another program and it was able to seperate the actor from the background. Luckily I have a green screen.
Posted: Wed, 18th Jul 2007, 12:23pm

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petet2

Force: 2899 | Joined: 27th Dec 2005 | Posts: 1043

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I think you are meaning a difference matte. This is where you film a background plate and then film the same shot with your actor/subject moving in front of it.

The program then analyses the two shots and removes all elements which are identical in both shots. Here's a guide to how it works from Adobe

http://livedocs.adobe.com/en_US/AfterEffects/8.0/help.html?content=WS3878526689cb91655866c1103a9d3c597-7b4b.html

and here's some tips on filming when using the technique

http://www.digitalvideofuel.com/filmingdiff.htm
Posted: Mon, 3rd Sep 2007, 12:41pm

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razerlazer2

Force: 440 | Joined: 18th Nov 2006 | Posts: 28

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u can use a mashk a roungd the person to cut them out but u have to edit the mask each frame.