Isolating X and Y tracking points

[Sam Moulton]

i’m not sure exactly how to do this but tracker info is an array [x, y] so you should be able to write an expression that looked at timeline markers and then held the y value at the marker time when the hand changes direction. It would be somethin like if time< marker 1 then [tracker value x, y tracker value] then if time > marker 1 use the value of x at marker 1 for x and the tracker value of Y for y and then change for marker 2, 3, and 4 as the rectangle is drawn.

I don’t know much about expressions but i’ll bet someone here could come up with the answer.

[Steve Roberts]

Hmm … if you track the person’s motion perfectly, you might not get a nice rectangle. Have you considered this?

1. draw a rectangular mask
2. apply effect>render>stroke
3. tweak the masks’s position to the picture
4. animate the stroke’s end point from zero to 100
5. add extra keyframes if necessary to follow the speed of the person’s hands

… assuming the camera is static. 🙂

If this doesn’t account for two-handed motion, try animating the start and end points, or adding vertices at the start and end points of the motion. Make one of those the “first vertex” of the mask (covered in the help).

Hope it helps,
Steve

[Wr Sampson]

Thanks for the suggestions Steve. The stroke render idea is a good one. Keyframes to follow the hands are probably the way to go too. The camera is static.

Tracking his hands precisely yields a very lopsided shape because human movement just isn’t exact. What I was hoping was that the X and Y values from a tracker would be available in a graph or table so that I could grab a whole region and hold them constant.

Sam’s idea of writing an expression is something to try as well.

Thanks again!

[Wr Sampson]

Cool idea. I’m going to mess with it a bit. The movement goes with a beat, so I could even start with markers generated by SoundKeys and modify them.

Thanks!