Follow Track Constraint

By default the Follow Track constraint is making objects have the same position at a frame as the track has and the motion of this object happens on a single plane defined by the camera and the original position of the object.

Active Clip
Receive tracking data from the active movie clip in the Movie Clip editor. If unchecked, an option appears to choose from the other available clips.
3D Position
Use the 3D position of the track to parent to.
Parent to the undistorted position of the 2D track.
Frame Method
Defines how the footage is fitted in the camera frame.
Select the camera to which the motion is parented to (if active an empty scene camera is used).
Depth Object
If this object is set, constrained objects will be projected onto the surface of this depth object which can be used to create facial makeup visual effects.
Constraint to F-Curve
Creates F-curves for the object that copies the movement caused by the constraint.