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Re: tracking a fast moving dot

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James Pierson
Re: tracking a fast moving dot
on Jan 23, 2014 at 4:27:29 pm

Hi Declan,

Thank you for taking the time to respond. Effectively what im trying to do is animate a whiteboard style animation in after effects.

Ideally i'd draw the characters inside illustrator with the line/pen tool, copy this into after effects as a mask, apply the stroke effect, reveal the line, and then copy the mask path properties onto the position layer of a hand holding a pan, sync up the key frames so it looks like the hands drawing out the image.

Its all great in theory but the problem I get is when I copy the path from illustrator into after effects, it comes in as 50+ masks(unfortunately trying the 'unite' function in illustrator doesnt help either)as the image is complex. This is fine to apply a stroke to, but I can't copy the mask path properties of each mask path into the position of the hand as its to time consuming and also would be difficult to sync up properly if I was using easing etc.

So! What I wanted to do, was to copy the path from illustrator to after effects, apply the stroke effect to 'all the masks' to get a nice reveal. I then duplicate the layer, and make the line colour vivid (in this case tried red) and thicken up the line. Now, rather than reveal all the lines as if being drawn out, I tried to make it so the stroke 'start' and 'end' keyframes made a dot that zipped along the front of the path.

I would then export this as a png sequence or mp4, bring it back into after effects, lay it over the initial image being drawn out, track the red dot data, then apply it to the hand image and hey presto it would follow along.

I've done white board animations inside after effects before by having the image I want to reveal, drawing a mask by hand over the top of it and applying stroke to it, to then copy the mask path into hand position. I'm certainly prepared to do it that way again, but I found its slightly time consuming, and when lines intersect it can be a little messy.

I just thought it seems like the answers so close what with illustrator/after effects path compatibility, but I can't figure it out! I was hoping it would be simple to track a red dot on a white background and my problem would be solved, but if I have to track the dot by hand every time it drifts off course then that would probably be more time consuming than my old method.

Any comments/work arounds I'm not seeing would be greatly appreciated!

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