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Offset Track: This parameter appears only when there is a tracking source (footage) in
the source well. If a tracker’s reference point becomes temporarily hidden or goes off the
screen, this parameter allows you to select a different reference point that continues the
same tracking path as the original reference point. For more information on offset tracking,
see Tracking Obscured or Off-Frame Points Using Offset Tracking.
Auto-Zoom: This parameter appears only when there is a tracking source (footage) in
the source well. Choose an option from this pop-up menu to set the magnification level
when positioning the tracker in the Canvas. This allows you to zoom in on the Canvas
when searching for an ideal tracking reference pattern. There are four choices: None, 2x,
4x, and 8x.
Auto-Zoom Mode: This parameter appears only when there is a tracking source (footage)
in the source well. Choose an option from this pop-up menu to set the display of the
auto-zoomed tracker in the Canvas. There are three choices:
• Normal: Displays a normal pattern.
• Contrast: Displays the tracker pattern with contrast detection.
• 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.
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 Giving Motion a Hint by Looking
Ahead.
Anchor/Rotation-Scale: Available when one-point or two-point tracking is enabled (when
Transformation is chosen from the Type pop-up menu), these checkboxes turn the Anchor
and Rotation-Scale trackers on or off. The anchor tracker records position data. When
Position is enabled in the Adjust parameters, the Anchor tracker is turned on. Rotation
and scale data are recorded by using the relationship between the Anchor and
Rotation-Scale trackers. When Scale or Rotation is enabled in the Adjust parameters, the
Rotation-Scale tracker is turned on.
When the Match Move behavior references another behavior, such as Analyze Motion,
the Anchor tracker becomes the Anchor pop-up menu. Likewise, the Rotation-Scale tracker
(if there is one) becomes the Rotation-Scale pop-up menu.
1348 Chapter 22 Motion Tracking