User Guide

405
ADOBE AFTER EFFECTS 5.0
User Guide
9 In the Tracker panel, click Analyze. Watch the tracking to make sure it is accurate. If not,
press any key to stop the tracking, and then correct the problem as described in
“Correcting a drifting feature region” on page 405. A black line appears in the time bar,
indicating the portion of the layer that has been tracked. Keyframes are not generated until
you click Apply.
10 To track multiple areas in the same layer, repeat steps 3 through 8 for as many areas as
you need. If you track a previously tracked area within the same track type, After Effects
generates new track data for the area.
11 When you are satisfied with the track, click Apply to generate keyframes for the
selected layer or effect point control you are attaching.
To delete a tracked area:
1 Reposition the In and Out points to include only the area of the track you want to
delete.
2 Press the Delete key. After Effects deletes only the tracked area between the In and Out
buttons.
Correcting a drifting feature region
There are two main methods for realigning a feature region if it drifts off track during
tracking. If most of the footage tracked accurately, you may need only to move the feature
region in selected frames. If drifting occurs early in the footage, you can modify the
tracking settings and then track again from the beginning.
Under certain conditions, you can correct drifting by simply enlarging the search region
(for example, if the search region is too small to contain erratic movement of the feature
region from one frame to the next). Note that increasing the size of the search region
increases the tracking time.
To correct drifting by moving the feature region:
1 Drag the current-time indicator to the last well-tracked frame.
2 Do one of the following:
UG.book Page 405 Wednesday, February 21, 2001 12:05 PM