As an image moves in a shot, the lighting, surrounding objects, and angle of the object can all change, making the once distinct feature no longer identifiable at the subpixel level. Also, if the search region is too small, the tracked feature may leave its bounds from one frame to the next.

Learning to choose a trackable feature takes time. Even with careful planning and practice, the feature region can drift away from the desired feature. Re-adjusting the feature and search regions, changing the tracking settings, and trying again is a standard part of automatic tracking. It’s not necessary to get a single good track in one try. You may need to track the shot in sections, redefining the feature region in places where the feature changes and the region drifts. You may even need to choose a different feature to track, one with movement that closely matches that of the feature to track, and use the attach point offset to place the target.

After you’ve tracked motion, each track point has a motion path in the Layer panel that shows the position of the center of the feature region. You can fine-tune the keyframes of the motion path in the Layer panel as you would any other motion path. Modifying the motion path is most useful when you want to manually change the motion tracking data before applying it to a target. In some cases, it may be easier to manually modify the motion path created by the motion tracker than to get a perfect track.

Motion source and its motion path

A.

Moving the feature and search regions

B.

Keyframe marker