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Permanently remove keyed out area, even after the color key fades

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Kjeld Schmidt
Permanently remove keyed out area, even after the color key fades
on Jul 25, 2016 at 9:06:42 pm

Hey,

I'm trying to achieve an 'erasing' effect. Basically, imagine a blue ball roling over a green background. Everywhere the blue ball has rolled to should permanently turn transparent.

Keying the blue ball is trivial. When setting out for this project, I expected to be able to 'export' the keylight data in some form onto a mask layer, presumably by using a, possibly compley, expression.

However, I fail to both see and successfuly google a way to get useful data from the keylight effect.

Can you imagine any way this is possible?

Thank you very much,
Best regards.


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Dave LaRonde
Re: Permanently remove keyed out area, even after the color key fades
on Jul 25, 2016 at 10:54:49 pm

I'm not certain what you're keying -- the ball or the background. I THINK you're keying the ball.

Sadly, there's no positional data preserved in Keylight. But you might be able to use AE's built-in tracker to track the ball's position. Mocha may also work for this job. Once you have a track, you can create a mask, which you can use for the Stroke effect to create a matte, which can get rid of the background.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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Kjeld Schmidt
Re: Permanently remove keyed out area, even after the color key fades
on Jul 26, 2016 at 8:03:52 am

Yes, I'm keying the ball.
Thank you for your help!


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Walter Soyka
Re: Permanently remove keyed out area, even after the color key fades
on Jul 26, 2016 at 5:41:07 pm

Try an inverted matte output from your keyer and apply the Echo effect. Tweak the echo time, number of echos, etc. to get a nice streak that shows the path of the ball. You can use this as an inverse luma matte for your background.

You will benefit from a clean key, some tight-ish garbage masking, and perhaps some matte adjustments here and there.

Walter Soyka
Designer & Mad Scientist at Keen Live [link]
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
@keenlive [twitter]   |   RenderBreak [blog]   |   Profile [LinkedIn]


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