4

The spinning animation of the line is applied to the Bezier shape. The tangents remain
aligned at their original angles along the shape.
Note: By default, Mimic Source is chosen from the Transform pop-up menu. For more
information on the Transform pop-up menu, see Track Points Controls.
Track Parameter Workflow
The Track Parameter behavior allows you to track a position parameter of a filter to a
reference feature of a clip, or to apply existing tracking data to a position parameter of
a filter. For example, you can track the center of a Light Rays filter to a moving light in a
clip.
Note: This behavior is only applicable to filters with position parameters, such as Scrape,
Ring Warp, Light Rays, Slit Tunnel, and so on.
For a full description of the Track Parameter behavior, see Track Parameter Behavior
Controls.
To use the Track Parameter behavior
1 In the Canvas, position the center point of the filter over the reference pattern.
In this simple example, the center point of a blur is positioned over the license plate of
a car.
Use the onscreen
controls to position the
center point of a filter on
the tracking reference
pattern.
Note: To use a filter’s onscreen controls, select the filter in the Layers tab, then choose
the Adjust Item tool from the 2D transform tools in the Toolbar. For more information
on using filters, see Using Filters.
1282 Chapter 19 Motion Tracking