User Manual

4 Connect the foreground to a corner-positioned node, so you can position the corners
of the foreground appropriately over the background.
5 Add another Transform node to the Node Editor after the Merge.
A second Transform after the Merge is used to add back in the original motion with Unsteady Poisition.
6 Connect the new Transform’s Center to the Tracker’s Unsteady Position. The image will
be restored to its original state with the additional effect included.
To better understand how this works, imagine a pattern that is selected at frame 1, at position
0.5, 0.5. The pattern does not move on frame 2, so its position is still 0.5, 0.5. On the third
frame, it moves 10 percent of the image’s width to the right. Now its position is 0.6, 0.5.
If a transform center is connected to the Steady Position output of the Tracker, the Transform
node’s center is 0.5, 0.5 on the first and second frames because there has been no change. On
frame 3, the center moves to 0.4, 0.5. This is the inverse of the horizontal motion that was
tracked in the pattern, moving the image slightly to the right by 10 percent of the image width to
counteract the movement and return the pattern of pixels back to where they were found.
Using the Tracker as a Modifier
Another technique for adding a tracker directly to a control is to add it as a modifier. Choosing
the Tracker from the Modify With contextual menu does not use a Tracker node; it adds a
modifier in the Inspector with a set of parameters almost identical to those found in the Tracker
node itself. The benefit here is that the object that you want to follow the tracked path is
automatically connected to the tracker modifier when you apply it.
Applying the tracker as a modifier.
The differences between a Tracker modifier and a Tracker node are as follows:
 The Tracker modifier can only track a single pattern.
 A source image must be set for the Tracker modifier.
Chapter – 73 Using the Tracker Node 1509