1.5

Will Motion Tracking Solve All Your Problems?
With shots where there is a clearly defined target (something high-contrast and angular,
preferably), automatic motion tracking can be the fastest way to quickly and accurately
animate a vignette to follow the motion of the subject or camera in a shot, but not
always.
If you’re working on a shot where automatic tracking is almost usable, but has a few
errors, you might be able to use manual tracking on top of the automatic track to correct
the most egregious mistakes, and then increase Tracking Curve Smoothness to get an
acceptable result. For more information about manual tracking, see Using the Tracking
Tab.
However, if actors or other subjects in the shot pass in front of the feature you’re tracking,
or if the motion of a shot is so fast that it introduces motion blur, or if there’s excessive
noise, or if there’s simply not a feature on the subject you need to track that’s
well-enough defined, you may need to resort to manual tracking for the entire shot,
which can be tedious if it’s a long shot. In many cases, manual keyframing may well be
the most efficient solution. For more information on keyframing, see Keyframing.
Using Motion Tracking to Animate Vignettes and Shapes
After you’ve processed a tracker, you can use that tracker’s analysis to animate the
following:
• A vignette in the Secondaries room
• A user shape in the Geometry room
• X and Y positions in the Pan & Scan tab of the Geometry room
• The Vignette node in the Color FX room
When applied to a vignette or a user shape, the animation of the Motion Tracker is added
to the X and Y positioning of the shape. For this reason, it’s most efficient to track a subject
and assign that tracker to the vignette, shape, or setting first, and adjust the positioning
later.
For example, suppose 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
should choose the tracker from the Use Tracker pop-up menu first. As soon as you choose
a tracker, the vignette or shape you’re animating moves so that it’s centered on the
tracked feature. At that point, you can position the center, angle, and softness of the
shape to better fit the person’s face. 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.
371Chapter 15 The Geometry Room