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) it is being tracked to. 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 analysis, then apply a
Match Move behavior to the foreground object.
2
In the Behaviors Inspector, choose Four Corners from the Type pop-up menu.
Note: The Four Corners option is not available when Match Move is applied to a 3D group.
To corner-pin a 3D group, select the Flatten checkbox in the Group Inspector.
1302
Chapter 22
Motion Tracking
In the Canvas, a tracker appears at each corner of the foreground object’s bounding box.
In the Inspector, the default track list (Anchor and Rotation-Scale), is replaced with the
Top Left, Top Right, Bottom Right, and Bottom Left trackers.
As with the Analyze Motion trackers, when you drag a tracker to a new position in the
Canvas, a magnified inset appears to help you position each tracker.
3
In the Canvas, drag each tracker to a corner of the background element (in this example,
the corners of the picture frame).
4
Click the Analyze button in the HUD or Behaviors Inspector.
The foreground element is pinned to the background element; four motion paths show
the transformation occurring at each corner.
Note: In this example, a reflection is created on the table using a duplicated and
transformed copy of the tracked image.
1303
Chapter 22
Motion Tracking
To fine-tune the track (when Four Corners is chosen from the Type pop-up menu), you
might need to make minor adjustments to the foreground element, such as modifying
its scale or rotation. When you choose the Attach to Source option from the Transform
pop-up menu in the Behaviors Inspector, you cannot transform the tracked object. To
transform the tracked object, choose Mimic Source from the Transform pop-up menu.
5
To transform the foreground element after the tracking data is applied:
a
From the Transform pop-up menu in the Behaviors Inspector, choose Mimic Source.
b
Open the Properties Inspector and make any necessary adjustments to the foreground
object using the Scale, Rotation, and other parameters.
For more information on the Mimic Source and Attach to Source transform options, see
Match Move Controls
.