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Table Of Contents
Understanding Motion Tracking
310
• Guidelines for Using Multiple Trackers When Stabilizing
• Using the Region Stabilize Effect
• Making Adjustments to the Region Stabilize Region of Interest
• Editing Segments That Use Tracking Data
• Reusing Existing Tracking Data
• Copying and Pasting Tracking Data
• Conforming Symphony Meridien Sequences with Tracking Data
• Examples of Effects Using Motion Tracking
Understanding Motion Tracking
This topic includes conceptual information that helps you to understand how tracking works and
when you might want to use it.
Understanding the Tracking Process
Motion tracking searches for a distinctive pattern of pixels in each frame of a video segment. As
the pattern moves over time, your Avid editing application records the movement as a series of
points, one for each frame or field in the segment. For example, if a car is moving across a
segment, you can track a distinctive pattern on the side of the car, such as the shape of its side
mirror. The result is a set of tracking data points that represent the movement of the car over
time.
Once you have a set of data points, you can associate them with an effect parameter to control
how an effect moves. For example, if you need to hide the identity of the person driving the car in
your segment, you can associate the tracking data with the Position parameter of a Blur effect.
The tracking data then controls the movement of the Blur effect so that the blurred area remains
over the person’s head throughout the segment.
Each set of data points is contained within a structure called a tracker. Depending on the kind of
motion you need to track, you might need one, two, or more trackers. For simple
two-dimensional movement, a single tracker is sufficient. If you need to track rotational
movement or scaling information, you need two trackers so that your Avid editing application
can calculate the position of one point in the image relative to a second point. For even more
complex motion, such as that involved in corner pinning an image, you might need three or four
distinct points to correctly track perspective or the angle at which the image is tilted.