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94 Chapter 2 Motion Tracking
To use a tracker for a portion of a stabilize operation:
1 Once the Stabilize motion analysis is complete, play the clip to determine what section
you want to track.
Important: Always analyze the entire clip before adding any trackers. The Stabilize
behavior needs “meaningful” data—a large range of frames—to yield the best results.
2 Set an Out point for the tracker analysis: Position the playhead at the frame you want
to stop the analysis, then choose Mark > Mark Play Range Out (or press
Command-Option-O).
3 Position the playhead at the frame where you want to start the track, then click the
Add button in the Inspector.
4 Position the tracker on the reference pattern you want to track in the Canvas, then click
the Analyze button in the HUD or Inspector.
The specified play range is tracked, creating track points in the Canvas and tracking
keyframes in the Keyframe Editor.
Note: When using this strategy to track multiple noncontiguous sections of the clip,
use the same tracker whenever possible to simplify the track and to avoid clutter in the
Keyframe Editor.
This strategy is not recommended for small portions of the clip, such as using the
default stabilization for 25 frames, a tracker analysis for 10 frames, the default
stabilization for 10 frames, and so on.
Changing the Smoothing Parameters
If you’re trying to smooth the motion in a clip, you should first try adjusting the
smoothing parameters. These parameters include Translation Smooth, Rotation Smooth,
and Scale Smooth. This can be accomplished without having to reanalyze the clip.
Reanalyzing at a Higher Quality
When analyzing, choose Better from the Quality pop-up menu in the Behaviors tab of
the Inspector. This may take longer, but the quality of the analysis is higher.
Editing the Analysis Data
If neither of the prior solutions helps, look at the Confidence parameter in the Keyframe
Editor, then look for frames where the Confidence parameter falls to very low values. If
the image transformation at these frames stands out, you can convert the Stabilize
behavior to keyframes. This creates transform keyframes on the stabilized object, which
can then be edited in the Keyframe Editor. Try deleting any keyframes that create
unusual spikes at the frames where the Confidence curve value was low.
For more information on converting behaviors to keyframes, see “Converting Tracks to
Keyframes” on page 84.