5

Note: When None is chosen from the Auto-Zoom pop-up menu, the Auto-Zoom Mode
setting has no effect.
Look Ahead Frames: This slider and value slider allow you to specify the number of future
frames to be analyzed by the tracker. In other words, you can direct the tracker to look
in a specific location for its reference point. This is useful for footage that contains
fast-moving objects, because the reference point can quickly get away from the tracker.
For more information on using Look Ahead Frames, see Giving Motion a Hint by Looking
Ahead.
Track list: This list displays the trackers in the behavior. In the Analyze Motion behavior,
the trackers in this list are called Track 1, Track 2, and so on.
To disable a tracker, deselect its checkbox. To remove a tracker, click the Remove button.
A tracker that is turned off is not analyzed.
Click the disclosure triangle next to the track name to reveal additional parameters:
• Position: This parameter displays the X and Y positions of the tracker. The X position is
the value slider on the left; the Y position is the value slider on the right. Click the
disclosure triangle to display labeled position value sliders.
• Track Size: This slider adjusts (in pixels) the pattern search size for the tracker. As you
adjust the tracker size, the Tracker Preview is updated to show the new tracker size.
There is no visual change in the Canvas tracker.
To adjust the Track Size without exposing its parameters, Option-drag left in the Tracker
Preview area to reduce the tracker size; Option-drag right to increase the tracker size.
• Search Size: This slider increases or reduces the tracker’s search area size. In Motion,
you do not specify the size of a search area when setting up trackers in the Canvas. To
change the default search size, use the slider or value slider. If Search Size is set to 200
percent, the tracker’s search area is twice the default search area size.
• Fail Tolerance: This parameter defines the amount of tolerance for error, or confidence
value, of the tracker. In other words, it defines at what score the tracker determines it
can match a reference feature. When above the score, the tracker accepts the match.
When below the score, the tracker rejects the match. When the match is rejected, the
Fail Behavior kicks in.
• Fail Behavior: This pop-up menu specifies what happens if the track confidence value
falls below the Fail Tolerance amount. The following options are available:
• Smart Retry: The tracker attempts to find the reference pattern in a larger search area.
If the pattern cannot be found, the tracker switches to the Predict option. Smart Retry
is the default fail behavior.
• Stop: The analysis stops when the tracker loses the reference pattern. You can also
click the Stop button in the tracking progress dialog or press Esc to stop an analysis.
1343Chapter 22 Motion Tracking