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Table Of Contents
Preparing to Generate Tracking Data
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5. Move the position indicator to the first frame or field of the segment, or to the first frame or
field of the tracker region.
A tracking box display appears in the Effect Preview monitor for each tracker. For more
information on tracking regions, see “Performing Offset Tracking” on page 333.
To move a tracking box display in the monitor:
t Click anywhere within the boxes except the adjustment handles, and drag the boxes to a new
position.
To resize a box in a tracking box display:
t Drag the adjustment handle for the box.
For more information on what to consider when making these adjustments, see “Guidelines
for Positioning and Resizing Tracking Boxes” on page 327.
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If you enable multiple trackers, you might find it difficult to select one. You can disable some of
the trackers temporarily in the Tracking window to simplify the display in the Effect Preview
monitor and make it easier to select and manipulate a particular tracker.
Guidelines for Positioning and Resizing Tracking Boxes
Positioning
When you position tracking boxes, consider the following:
Locate the boxes over material that your Avid editing application can track successfully.
Locate the boxes so that the tracking data you generate accurately represents the movement
you want to track.
Tracking works most successfully on an area of the image that is easily distinguishable from its
surroundings. For example, a bright dot tracks extremely well if darker material surrounds it.
You often need to scrub through the entire clip to determine which areas are good candidates for
tracking.
To represent the movement you want to track accurately, you must consider the geometry of the
motion that you want to achieve. For complex movement, such as controlling a replacement sign
for a bus that is receding into the distance as well as moving across the screen, you must track
enough points to represent the change in shape and size of the sign over time. Tracking two
corners lets you control changes in scale and rotation (the corners should be diagonally opposite
if scaling on the X axis differs from scaling on the Y axis). Adding third and fourth trackers fills
in the other two corners as needed for more complex transformations.