After Effect: Create Stroke from Motion Track Path

Question

In After Effect, I tracked a moving object in my Video with the Motion Tracker. There I got Keyframes, which I want to use. Now, I would like to show the path of my object in the Video. I thought to use the stroke effect, to get one stroke that is builded when it "follows" my object. The goal is, that the stroke shows in the end the path of my object.

Do you know how to accomplish this task? I don't now how to modify the position keyframes from motion tracker that I can use them in "stroke". (Thought also to interpolate them with bezier, but what's next?)

Thanks for your help!

Max

Answer 1

Select the motion keyframes & copy. Now create a new mask on the layer on which you have the stroke effect, any old mask shape will do. Set its mode to none. Now select the mask's Mask Path property and paste. The mask can now be used to provide the path for the stroke effect (it's the first property in the stroke effect). You have to directly select the Mask Path property, just pasting it on the layer will paste it to the position property of the layer.

Because there's always more than one way of doing things in AE:

You can also create a shape layer with the pen tool. Once you've done expand the new shape layer until you see the Contents>Shape 1>Path property (it could be called Shape 2, 3 etc) and paste the motion path on to it. Then you can use it as a normal stroked shape layer.

Note As Alyssa points out below, when pasting a motion path to some other property you have to explicitly select that property, otherwise AE will just paste it on to the layer's position.

Answer 2

Not sure how to do this with the stroke effect.

But you can use a particle generator set the movement and physics to 0 and link the particle source to the trackpoint. This will generate a stroke of particles, and if you ramp up the amount of particles you can make a solid line.