5

Important: To move the tracker positions independently of the foreground object, choose
Mimic Source from the Transform pop-up menu in the Behaviors Inspector. When Attach
to Source is chosen from the Transform pop-up menu, the foreground image is distorted
when you drag the trackers in the Canvas.
6 Click the Analyze button in the HUD or Behaviors Inspector.
The foreground object is pinned to the background element.
Note: If you adjust the Four Corner parameter for a layer and then apply a Match Move
behavior, the Four Corner parameter is applied in the behavior. If you delete the behavior,
the four corner settings for the layer remain. If you reset the Match Move behavior, the
four corner settings are reset.
Masking and Tracking
When a mask is added to an object with applied tracking data, the data is applied to the
mask. In the following image, the foreground object is tracked to four points on the
background clip, but still must be masked to fit into the picture frame.
By masking the image being tracked, you can include only the portion of the image you
want to fit in the frame.
Although the mask is attached to the foreground image, you might need to animate
changes in the mask’s position and scale to accommodate changes in the background
clip over time.
1308 Chapter 22 Motion Tracking