Apple Color 1.0 - Manual (Page 307)

Chapter 15 Geometry 307
Using Motion Tracking
After you’ve processed a tracker, you can use that tracker’s analysis to animate a
Vignette, User Shape, or Pan & Scan setting. When applied to a Vignette or a User
Shape, the animation of the motion tracker is added to your original positioning of the
shape. For example, if you’ve used a tracker to follow the movement of someone’s eye,
and you want to apply that motion to a vignette that highlights that person’s face, you
need to position the center, angle, and softness of a circle-shaped vignette over the
person’s face at the first frame of the shot, and then choose the number of the tracker
from the Use Tracker field. This way, the vignette starts out in the correct position, and
goes on to follow the path created by the tracker. Because the tracker uses an
additional transformation, you can still reposition the vignette using the X and Y center
parameters or the onscreen control in the Previews tab.
If you track a limited range of a shot’s total duration by setting In and Out points for
the tracker that are shorter then the length of the shot, the vignette stays at the initial
position you drag it to until the playhead reaches the tracker’s In point, at which time
the vignette begins to follow the tracker’s motion path. When the playhead reaches the
Out point, the vignette stops, and remains at that position until the end of the shot.
Controls in the Tracking Tab
The Tracking tab has the following controls:
 Tracker List: A list of all the trackers that have been created for the shot at the current
position of the playhead. This list has three columns:
 Name: The name of that tracker. All trackers are named in the following manner:
tracker.idNumber
 ID: The ID number that corresponds to a particular tracker. This is the number you
enter into any Use Tracker field to specify which tracker to use to animate that
adjustment.
 Status: A progress bar that shows whether or not a tracker has been processed.
Red means that a tracker is unprocessed, while green means processed.
Will Motion Tracking Solve All Your Problems?
With certain shots where there is a clearly defined target (something high-contrast
and angular, preferably), motion tracking can be the fastest way to animate an effect
to follow the motion in a shot, but not always.
If actors or other subjects in the shot pass in front of the feature you’re tracking, if the
motion of a shot is so fast it introduces motion blur, if there’s excessive noise, or if
there’s simply not a feature on the subject you want to track that’s well-enough
defined, using a Manual Tracker may work, although manual keyframing may still be
your best option. For more information on keyframing, see Chapter 14, “
Keyframing ,”
on page 285.