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Chapter 2 Motion Tracking 77
Note: Keep in mind that paint strokes usually have a very large number of control
points. You should simplify a paint stroke by deleting or disabling control points prior
to applying a Track Points behavior to the stroke. To track the stroke as a whole, rather
than by its control points, use the Match Move behavior.
2 Drag the trackers to their reference patterns.
As you drag, a magnified view of the area around the tracker appears.
3 To disable a tracker, turn off its checkbox in the Behaviors tab of the Inspector.
Note: Any control points without an associated tracker are not modified.
4 Click the Analyze button in the HUD or Behaviors tab of the Inspector.
The mask control points are tracked to the reference patterns. In this example, the
moving car is masked so that it is isolated. Blur and desaturation effects are
subsequently applied to the background, without affecting the car.
Note: As with all behaviors, you can drag or copy (Option-drag) a Track Points behavior
to a new shape in the Layers list. When you apply the behavior to a new shape, the
behavior is reset.
Original unmodified clip A tracked mask isolates the car in the shot,
allowing separate effects to be applied to the car
and its background.