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a magic wand tool for contiguous pixels ?

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Lucia Bastenhof
a magic wand tool for contiguous pixels ?
on Apr 10, 2010 at 8:46:18 pm

Hi everyone ! :)

Am I in a desperate situation ? Here is the case :

There are 1 or 2 freehand closed paths, drawing many separated loops.
The layer the paths/masks are applied on is visible only through some of those loops.
I'd like to fill those loops with different materials. In one loop an image, in another a video, in a third one a plain color....
Then, you could tell me : that's easy, you just have to stick everything in the right places in a precomp, and you apply the masks on this one. Done !

But it's a little more difficult : I want to animate those masks. The different loops drawn by them would grow or shrink during time, and of course I'd like the materials seen through them (image, video, color....) to be more or less visible meanwhile.

Maybe I should paste the same masks on different layers, one layer for each material... but the problem remains : how can I tell After Effects I want to isolate one loop from the others ?

Creating another mask in order to hide the other loops means changing its shape manually on each frame... Not imaginable with many loops.

I thought about the magic wand tool in Photoshop, which can select only the contiguous pixels. It would allow me to select only one loop, and to hide the others.
I thought about exporting a simple video in a filmstrip file, from AE to PS, to use the magic wand there. But I suspect this "solution" to be an incredible pain... :-(

Do you have an idea about all that ? A way to recreate a "magic wand tool for contiguous pixels" into After Effects ?
Or maybe are there completely different solutions ?

Great thanks for your great ideas ! :-)

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Walter Soyka
Re: a magic wand tool for contiguous pixels ?
on Apr 11, 2010 at 12:24:00 am

You could use the Paint Bucket effect on a precomp of your loops to create luma mattes for your materials layers.

Paint Bucket works like the paint bucket tool in Photoshop, but of course you can add keyframes. You could step through your animation a frame at a time pretty quickly, just adding keyframes to the fill point where necessary. Depending on your loops, you might even be able to track them.

Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
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Lucia Bastenhof
Re: a magic wand tool for contiguous pixels ?
on Apr 11, 2010 at 2:51:40 am

Hi Walter ! :-)
Thanks for the idea, I had never used this tool in AE ! :-)
And what's great is that I don't even have to go through each frame separately, I just have to specify the right Fill point !
That said, it has some strange behaviour though.
For instance, I specified a Fill point in one loop, but when I make a preview, one other loop is filled as well, one frame here one frame there.
I tried to resolve it by animating the Fill point, but it doesn't work : wherever I put the Fill point (into the 1st loop), the 2nd loop is filled as well.
Whereas one frame earlier or after, everything's fine.

I can't find the logic in there. Any ideas ?
By the way, if there are other effects that would be used in this situation, it still interests me ! :-)

Thank you all,

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