Apple Motion 4 - Manual (Page 1263)

Four-Corner Pinning with Match Move
The Match Move behavior allows you to track four points on a background clip and apply
the motion to the four corners of a foreground element. There are three possible
four-corner pinning workflows. In the first example, a foreground element is pinned to
a background element using the four-corner trackers. This workflow is useful when the
“pinned” image is the same size as the background reference patterns to which it is being
tracked. In the second example, the foreground element is corner-pinned prior to using
the four-corner trackers. This allows you to position the element in the correct location
on the background element prior to applying the Match Move behavior. In the third
example, the foreground object is transformed to fit a background picture frame using
the scale, rotation, and position parameters in the Properties tab prior to applying the
Match Move behavior. This workflow is helpful when you prefer to adjust the “pinned”
image prior to being tracked.
Motion offers many different tracking workflows because shots vary so greatly, and
tracking success is unpredictable. Several tracking attempts are often required before a
satisfactory track is achieved.
Tip: If one of the pinning options below doesn’t result in a successful track, try another
option. There is an additional four-corner pinning workflow that can be performed using
the Analyze Motion behavior.
Note: You can also perform four-point tracking using the Analyze Motion or the Stabilize
behavior. For more information, see
Using a Non-Match Move Four-Point Track for
Corner-Pinning .
There are special considerations when corner-pinning groups. For more information, see
Tracking and Groups .
Option 1: Pinned Image Is Locked to the Reference Points
This workflow is ideal for a four-corner pin in which the transformed or “pinned” image
is the same size as the background “frame” (or reference patterns) to which it is being
tracked. In the following example, a foreground image is pinned to a background clip of
a picture frame.
To track an image using four trackers
1 Drag the playhead to the frame where you want to start the track and apply a Match
Move behavior to the foreground element.
1263 Chapter 19 Motion Tracking