Apple Motion 5.1.1 - Manual (Page 975)

Chapter 22 Motion tracking 975
Track a mask using the Track Points behavior
In the following example, the Track Points behavior is applied to a loose mask of seven control
points isolating a car in a background clip.
1 With a background clip visible in the Canvas, use a mask tool to isolate part of the background clip.
For more information on working with masks, see Masks and transparency overview on
page 888.
2 Select the mask object, then choose Shape > Track Points from the Add Behavior pop-up menu
in the toolbar.
The behavior is added to the mask object, and trackers appear for each control point on the
shape. The trackers are ordered in the same order that the shape was drawn: Control Point 1 is
Track 1, Control Point 2 is Track 2, and so on.
3 Drag the trackers to fine-tune their position on the reference patterns.
As you drag, a magnified inset view of the area around the tracker appears.
4 To disable a tracker, deselect its checkbox in the Behaviors Inspector.
Note: Control points without an associated tracker are not modified.
5 Click the Analyze button in the HUD or Behaviors Inspector.
The mask control points are tracked to the reference patterns.
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