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How to Hide some Part of the clip and replace it with something else

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Taha Kirmani
How to Hide some Part of the clip and replace it with something else
on Jan 10, 2011 at 9:08:00 pm

Hello
I created a video ,that a Man is running on Playground , and suddenly he hit by a stone and fall into the floor .
The problem is that , when Man hits the floor , he lay into the Red Color Badsheet ,not into the sand , because he did not wanted to lay on the Ground and get dirty .
The Problem is that my camera is moving alot , if i use Masking , i think i need to create couple of masks , and i need to rotate them alot .
Is there any other way to do this .

Regards,
Taha .


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Dave LaRonde
Re: How to Hide some Part of the clip and replace it with something else
on Jan 10, 2011 at 10:42:45 pm

From your description, this will be very difficult to do.

It's not easy to do a chroma key on red. You may have to rotoscope the subject to separate him from the background. Here are some resources:
http://community.adobe.com/help/search.html?q=rotoscoping&hl=en_US&lr=en_US...

If you can separate the subject from the background successfully, you now have to replace the background. Do you have a background that will work? Since your camera moves you may also have to use motion tracking. Here are some resources:
http://community.adobe.com/help/search.html?q=motion+tracking+in+after+effe...

It seems that during your shoot, you thought you could do this in After Effects, but you didn't know HOW it would be done in After Effects. When you do things that way, you make a lot of work for yourself later.

I wouldn't want to fix your shot.

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


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Todd Kopriva
Re: How to Hide some Part of the clip and replace it with something else
on Jan 11, 2011 at 1:56:17 am

The Problem is that my camera is moving alot , if i use Masking , i think i need to create couple of masks , and i need to rotate them alot


That is normal. Rotoscoping is complex, tedious work.

Just for comparison, I recently had to rotoscope to separate a man's upper body from a background, and I had to use eight masks to to it, each animated frame by frame. And that was a simple shot, since his lower body was blocked by a desk.

There are many ways to separate a foreground subject from a background. The most common ways are listed here:
"Compositing overview and resources"
The ones that aren't a lot of work (such as color keying) take a lot of planning and discipline during shooting.

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Todd Kopriva, Adobe Systems Incorporated
Technical Support for professional video software
After Effects Help & Support
Premiere Pro Help & Support
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