I'm not Jurgen but hopefully you'll take comments from the peanut gallery.
I would break down the problem into these pieces:
- Identify the ball
- Determine its position
- Record the position
- plot or analyze
Identification is the hard part. It is greatly simplified if you have high contrast such as a bright ball against a dark background especially if the ball is a constant size that is not moving toward or away from the camera.
For something like that a simple thresholding technique works pretty well. Some simple algorithm to remove extraneous points might be needed.
Then the position could just be the center of gravity of the points identified as the ball.
What you end up with is the (x,y) position of the ball in the frame. Assuming a constant time per frame you can just store it in 2 vectors and use Matlab plot function to display it.
Joe
