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keying out a moving object

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peter crawfordkeying out a moving object
by on Feb 3, 2011 at 8:38:33 am

Would hugely appreciate any advice.

I've been given some time lapse footage of a flower opening (against a multi coloued background), and my client would like thie flower to be keyed out.

I have experience with keying well shot blue/green screens using FCP, MOTION, COLOUR AND A EFFECTS, but am unsure how to do this with footage not shot against a proper screen.

Is this Rotoscoping I need to learn abbout or is there an easier way to simply travk a mask in one of the prior mentioned programmes. I am new to AE.

Thank You

Pete Crawford

paxpincer


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Cassius MarquesRe: keying out a moving object
by on Feb 3, 2011 at 12:17:09 pm

does the background change at any time? is it moving? if it's not and the colors don't match exactly, you can try and get a clean plate of that background and use a difference matte to key out the flower pretty much automatic. Even though it's a bit rough effect for my taste.

A few screen shots of your footage could help us see the best option.

But I'm imagining that rotoscoping would be the way to go.


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Tudor "Ted" JelescuRe: keying out a moving object
by on Feb 3, 2011 at 12:22:27 pm

It sounds like a job for Roto Brush - check out Adobe help and feature tour.
You could also try Roto with Mocha.

Tudor "Ted" Jelescu
Senior VFX Artist


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Michael SzalapskiRe: keying out a moving object
by on Feb 3, 2011 at 2:29:02 pm

You could certainly try Roto Brush. I'd recommend going to this page [link] first before you try to use it. It's not a very intuitive tool and you can end up frustrated.
This page [link] lists a ton of tips, tricks, shortcuts, and more to help with conventional rotoscoping. Even if the Roto Brush works for you, you will probably have some cleanup to do and, if the Roto Brush doesn't work, you'll have to resort to it anyway.

- 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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peter crawfordRe: keying out a moving object
by on Feb 4, 2011 at 7:57:40 am

Hi , Thanks heaps for the quick reply,

No the background doesnt really change just the foreground orchid 'blooming'
Unfortunately the background is red/maroon which is very similiar the the flower itself.
The file is also 1 minute 15 sec long so especially being new to rotosoping I shudder to think how long this would take me.
I tried a test in FCP using the difference matte you suggested, but I think I am doing something wrong...
I exported a still image of the file to photoshop, cut out the orchid and clone stamped the backgound, then impoted back to FCP
I then put my main primary footage into the top timeline and the still background on the bottom. I then applied a difference matte to the main footage.
The result was simply the background, so I inverted which didnt seem to do much.
I would like to end up with simply the orchid doing its thing with a keyed background.

Ill try to upload an image
1594_picture2.png.zip
Thanks

Pete

paxpincer


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Cassius MarquesRe: keying out a moving object
by on Feb 4, 2011 at 11:07:13 am

you've got a very defined edge around the flower... if you have access to AE cs5, you should definitely go for the roto brush.


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Dave LaRondeRe: keying out a moving object
by on Feb 4, 2011 at 4:12:10 pm

Since there's such a marked difference in luminosity between foreground and background, you may also be able to animate a garbage mask and use a combination of the Levels, Threshold and Minimax effects to build a matte, which can then be used to isolate foreground from background.

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


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peter crawfordRe: keying out a moving object
by on Feb 4, 2011 at 9:54:47 pm

great thanks everyone

paxpincer


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