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Applying tracking data to a path vertex?

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Bob Woodhead
Applying tracking data to a path vertex?
on Sep 4, 2013 at 12:13:22 pm

Scenario: have an actor walking with a phone. I want to have a curved line (Bezier, prob) that has one end "attached" via tracking data to the phone and the other end manually positioned. No problem with the tracking part, done that often. But usually I attach an image, etc via the track, never done a portion of a path segment.

So:
- how to attach track data to only one vertex of a Bezier path
- if I wanted a multi-vertex Bezier or RotoBezier path (for more shape than a simple curve), how to have "falloff" of influence from the track-managed vertex? (was wondering if somehow the Puppet tools could work)
- or is there another direction to take for a solution?

Not looking for step by step answer really, just something to get me going in the right direction.

As always, thanks!

"Constituo, ergo sum"

Bob Woodhead / Atlanta
CMX-Quantel-Avid-FCP-Premiere-3D-AFX-Crayola
"What a long strange trip it's been...."


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Cassius Marques
Re: Applying tracking data to a path vertex?
on Sep 4, 2013 at 2:09:00 pm

Well, This script would help you link positional data to a mask vertice. Unfortunatly its kind expensive if you need for just that example. There are others scripts there that work/assist with masks there are "name your own price" and may be able to assist you.

For example Keytweak would help you interpolate masks to visually give that "falloff".

Edit: Thinking about it now, You may be able to pull that out with a line and puppet tools, if not actually needing a mask is an option. You can easily link a puppet point to your tracked mask with the pickwip.


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Bob Woodhead
Re: Applying tracking data to a path vertex?
on Sep 4, 2013 at 3:00:07 pm

That's right, not masking anything, this will be a visible line connected at one end to the tracked phone in the hand, and the other end of the line connects to a "thought bubble".

Would a puppet point distort the line in an odd way? That is, I'd want the line to love as if I was simply animating one end vertex.

Maybe there's another approach.... how about applying track data to a point in a plugin that creates a line? So there's direct keyframe access to the point (unlike a shape vertex).


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Cassius Marques
Re: Applying tracking data to a path vertex?
on Sep 4, 2013 at 5:01:45 pm

you can apply the data to one end of the beam effect, but that will give you a straight line not a bezier curve.


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Jason Jantzen
Re: Applying tracking data to a path vertex?
on Sep 5, 2013 at 12:49:25 pm

Seems that Motion Boutique's free script ConnectLayers would do the trick here. There's an option for bezier lines with the "Rope" button. The way it works, tho, is with an animated null or shape or any layer really and it attaches to the anchor point of that animated layer. Obviously you need more than 2 layers to create a bezier curve with rope, so more than 2 points to create the curve. Anyway, after you've run the script, it creates the line via shape layer, and it's not really controllable other than animating the stroke or applying other shape layer effects to it. So you need all your keyframes BEFORE running the script.

Jason Jantzen
vimeo.com/jasonj


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Bob Woodhead
Re: Applying tracking data to a path vertex?
on Sep 5, 2013 at 1:50:16 pm

Yeah, I'm playing with ConnectLayers right now.... a bit rusty in AFX, so it's going slow.

Still searching for some kind of "line" plugin that uses points that could be null-driven (from a track path).


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Jason Jantzen
Re: Applying tracking data to a path vertex?
on Sep 5, 2013 at 5:08:41 pm

if you mind sharing your project, I wouldn't mind taking a look at what you've got and setting something up. I think the ConnectLayers script will get you most of the way there, but I'm not entirely sure what your'e situation is since you say you're still looking for something to drive the end points of a line with nulls and that's exactly what ConnectLayers is designed to do.

Jason Jantzen
vimeo.com/jasonj


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Bob Woodhead
Re: Applying tracking data to a path vertex?
on Sep 5, 2013 at 6:02:02 pm

Why thanks Jason. I don't even have a formal project yet... I'm doing preproduction research so when it comes to the script/shoot I haven't painted myself into a corner, effects-wise. aka, "seemed like a good idea at the time"!

What I'll have is some tracked positional data, translation only - rotation and scale aren't necessary I think. And a Bezier curve (dotted line) with one end manually animated, and the other end getting the XY tracking data.

I was hoping to put time into it this morning, but had 5 other projects get in the way. And I wonder why I never have the time to get expert in AE.....

W/O having spent the time I need to on Rope, I'm wondering if it can work with say 1 out of 3 nodes on a Bezier curve (or maybe just 2)? Imagine a simple half sine wave curve, it can be defined by as few as 2 nodes. So if Rope can "drive" that, the solution is there. Though in a perfect world there'd be more complexity to the curve, and the tracking data "pulls" one end.... now that I think about it, EXACTLY like inverse kinematics in 3D. yeah, that!


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