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Compositing CGi and Video ?


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I have a CG render to drop "into" live video footage of a busy street scene (pedestrians, traffic etc). I therefore need to "cut out" the moving people, and drop the CGi behind. I know I can use masking in Vegas, but its a very time intensive process so was hoping for a better solution / software. Any help greatly appreciated.

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Unless the people happen to be walking past a relatively uniform coloured surface that you could key out then I'm afraid rotoscoping (masking frame-by-frame) looks like your only answer, regardless of software.

 

Indeed! I've seen people actually placing massive tarpaulin sheets over buildings that need to be roto'd before, because the time it takes them to do that (a few hours) is often significantly less than the time it takes them to roto out all the people and traffic. Obviously this is only the case on busy scenes.

 

I've also seen technology whereby you can select corners of an object, and then the programme basically cycles through all the frames and gives you a "blank" plate of the background - ie, it looks at what's moving and what's constant, and creates an image based on the "gaps" in the crowd. You could effectively use this to highlight the difference between this plate and the video and thus automatically roto the people, but I must admit I've never personally done this, cannot recommend any specific software and have no experience doing it, so it's a bit of a wildcard!

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yeah unless you have a uniform background its going to be hell rotoing the people, it will look scrappy as well unless its good HD or above footage.

 

blue tarps and green cloth are your best hope.

 

here is a pic from our last shoot with our 'greencloth'

before and after.

 

DSC_0282.jpg

 

517_the_moon_04.jpg

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