First track (autotrack) the hip, knee, and ankle as 3 point masses. Then click the measuring tool button on the toolbar and create a protractor, which will be selected by default. Click the protractor button on the track bar and choose Attach Points. Then in the Attach Points dialog attach the vertex, base and arm of the protractor to the hip, knee and ankle as desired. Make more protractors to attach to other points as needed.  The protractors generate angular position, velocity and acceleration data as well as base and arm lengths.


> I want to use Tracker to analyse sprint mechanics.
> Is there a way to (auto)track limb angles and limb
> angle velocities if I place markers on certain spots
> (hip, knee, ankle)?