Turning a solid mask into an outline/edge mask effect?

HOST: After Effects

Hello - I am wondering if there is a specific way to turn a masked object, e.g, like a completely masked circle so that the mask is only applied to the outer edges/margins of the circle.

Is there a specific boris fx effect that can accomplish this?

Thank You


Hi, I don’t know about an effect but,
Open splines only mask the line of the spline,

If you create a spline within a spline using the spline option with a + it cuts out that part from the orig,

Or if you create a spline, duplicate it, set Edge Properties of the copy to -1, click Set then click + it shrinks the copy by 1, set that copy to Subtract, that’ll then show just a ring around the circle you masked.

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Thanks for the options GID I appreciate it. I will give those a shot when I mess around with Mocha.

I was more wondering if there was an effect in the pack to do this with a pre-existing mask created in AE, ; without having to use Mocha. I know in AE you can turn a mocha mask into an AE mask but I don’t believe the converse is true, unless I am wrong which I might be, lol. Thanks again! You are the most helpful person on this forum btw.

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:+1: The last one copy & shrink is what i use to outline things,
I thought you were using Vegas, i’m getting old n stupid :man_facepalming::rofl:
I don’t know about AE but isn’t there an option to Stroke the path (Spline) ?

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That is awesome Gid thanks for that makes it very clear so if I used Mocha I know how to achieve that effect thanks again for clear succint demo!!

That’s an elegant solution with Mocha, Gid. Thanks.

RomanAnthony, if you want to use AE’s own masks you could use AE’s Stroke effect to generate a white outline of the AE mask. This could then be used as the source for a track matte, etc.


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Thank You!!! I will try that out I really appreciate the time and advice, both of you.