1 person found this helpful
One tracking point allows you track an object's position. Two tracking points allows you to track rotation. This is a standard function of AE's built in motion tracker, but you could also use Mocha if you wanted to.
You need to track the position of the finger (probably the finger tip), and you also need to track a second point on the finger. Ideally, that point would be above the first finger joint, so that if the finger bends at the joint the object will rotate with it. Depending on the resolution and the scale of your shot this may not be possible.
1 person found this helpful
As Andrew said you will need two tracking points. Depending on the shot AE's point tracker may work better than Mocha. You may even be better off stabilizing the shot so that the finger does not move in the frame, animating the pointing object by hand, then removing the stabilization from the shot and adding the movement from the stabilized shot to the animated layer.
If you could post a few frames of the video on YouTube or Vimeo we could give you a better idea.
Andrew - I had understood about the rotation tracking, I guess my concern was that how would I apply that data to an object that would be, say, 6 inches out from the finger because the movement of the object would be more exagerated due to the distance out... would I need an expression on top of it?
Rick - How would I add the stabilized shot information to my object layer? also, Would you be talking about using the Warp Stabilizer in CS6?
When you stabilize a shot using AE's built in stabilizer (not the warp stabilizer) you pick some points on the shot that you don't want to move, run the analysis, and then click stabilize. The part you stabilized should now not move in the frame but the rest of the video will be moving around.
Did you follow that? If you stabilize a hand and a finger then the hand and finger will not move but the rest of the shot will be moving around the hand and finger.
U will reveal the keyframes. There will be some for anchor point and rotation
You then add a layer for your artwork. It doesn't move so you can position it exactly where you want it and do any animation easily.
The easiest way to add the motion to the new artwork and remove the stabilized shot is to simply add a camera that has about the same focal length as your original shot, make the footage and the artwork layers 3D layers, then parent the camera to the footage.
You can also copy the anchorpoint keyframes to the position keyframes for the artwork and use a -Value expression added to the rotation keyframes that you copy and paste to the artwork.
Here's a tutorial that should get you started.
Without seeing a sample of your footage I can't give you any better pointers than that.
Thank you so much Rick, that worked brilliantly!
Don't know if I should do a separate question, but how would you do the same for 2 hands? Ie like if someone was juggling something back and forth (Trying to animate the "something")?