Apple Motion 5.1.1 - Manual (Page 1005)

Chapter 22 Motion tracking 1005
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Edge: Displays the tracker pattern with edge detection. The Auto-Zoom Mode applies to
trackers in the Canvas and does not appear in the Tracker Preview in the Behaviors Inspector.
When None is chosen from the Auto-Zoom pop-up menu, the Auto-Zoom Mode setting has
no effect.
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Look Ahead Frames: This parameter appears only when there is a tracking source (footage) in
the source well. 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
Advanced strategies to improve tracking results on page 984.
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Track list: Tracks appear only when there is a tracking source (footage) in the source well. The
Track List shows the trackers in the behavior as Track 1, Track 2, and so on. The number of
trackers is determined by the number of control points on the shape with the applied Track
Points behavior. For example, when a Track Points behavior is added to a shape with 12 control
points, 12 trackers appear in the track list.
When another track is referenced, the track list is replaced with Control Point pop-up menus.
To disable a tracker, deselect its checkbox. To remove a tracker, click the Remove button. A
tracker that is turned off is not analyzed with the track.
Click the disclosure triangle next to the track name to reveal these additional parameters:
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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.
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Track Size: Use this slider to adjust (in pixels) the pattern search size for the tracker. As you
adjust the track size, the Tracker Preview is updated to show the new track 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 track size; Option–drag right to increase the track size.
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Search Size: Use this slider or value slider to increase or reduce 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.
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Fail Tolerance: Use this parameter to define the amount of tolerance for error, orconfidence
value, of the track. In other words, it defines at what score the tracker determines it is able
to match a reference feature. When above the score, the tracker accepts the match. When
below the score, the tracker rejects the match. After the match is rejected, the Fail Behavior
kicks in.
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Fail Behavior: Use this pop-up menu to specify what happens if the track confidence value
falls below the Fail Tolerance amount. The following options are available:
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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.
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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.
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Predict: The tracker predicts a new search area without creating keyframes until it finds
a match for the reference pattern. This is excellent for tracked objects that pass behind
foreground objects.
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