User Guide

399
ADOBE AFTER EFFECTS 5.0
User Guide
Tracking different types of motion
The Tracker/Stabilizer can track five different kinds of motion—position, rotation,
position and rotation, affine corner pinning, and perspective corner pinning. For each
type of motion, define one or more tracking regions. If you switch between tracking types,
the Tracker/Stabilizer retains the track points, tracker settings, and tracking data of your
last track type, and displays them correctly the next time you choose that track type.
Tracking position
When you track position, you are attaching a layer or an effect to a single point. The
attached layer floats over (or under) the tracked point and is not distorted or skewed to
simulate perspective. For perspective, use perspective corner pinning. For more infor-
mation, see “Tracking position using perspective corner pinning” on page 402.
To define tracking regions for position:
1 Size the feature region to include only the object you are tracking.
2 Size the search region to accommodate the movement you are tracking. If the motion
is jumpy and sudden in one or more directions, stretch the search region in those direc-
tions, so that the Tracker/Stabilizer can accurately find and match the suddenly shifting
pixels. If motion is smooth in all directions, you can size the search region to be just
outside the feature region, to minimize tracking time.
3 Drag the track point anywhere within the layer. If you want to attach the second layer
directly on top of the feature region, place the track point in the center of the feature
region. If you find that the second layer is not positioned correctly during tracking, you
can stop the track and adjust the track point by dragging it and, if necessary, monitoring
the tracking coordinates (for details on the tracking coordinates, see “Working with the
Tracker/Stabilizer Controls” on page 394). After you apply the tracking to the second layer,
you can also adjust the layer’s anchor point to reposition it.
Tracking rotation
When you track rotation, you duplicate the rotation of a specified region in one layer in
another layer. When tracking only rotation, the Tracker/Stabilizer does not track position
but generates only rotation keyframes for the second layer. In other words, the second
layer is not attached to the first; the second layer remains in the position you have specified
in the composition, rotating relative to the specified region’s arc of rotation.
UG.book Page 399 Wednesday, February 21, 2001 12:05 PM