User Manual

Operation Tab
While the Trackers tab controls let you customize how the Tracker node analyzes motion to
create motion paths, the Operation tab puts the analyzed motion data to use, performing image
transforms of various kinds.
The Tracker node is capable of performing a wide variety of functions, from match moving an
object into a moving scene, smoothing out a shaky camera movement, or replacing the content
of a sign. Use the options and buttons in the Operation tab to select the function performed by
the Tracker node.
Operation Menu
The Operation menu contains four functions performed by the Tracker. The remaining controls
in this tab fine-tune the result of this selection.
 None: The Tracker performs no additional operation on the image beyond merely
locating and tracking the chosen pattern. This is the default mode, used to create a
path that will then drive another parameter on another node.
 Match Move: When only the orange background input is connected, this mode
stabilizes the image. When a foreground image is connected to the green foreground
input, the foreground image matches the position, rotation, and scaling based on
the tracking patterns. Stabilizing and match move require a minimum of one tracking
pattern to determine position, and two or more to determine scaling and rotation.
 Corner Positioning: The Corner Positioner mode tracks the four corners of a
rectangular object and replaces the contents with a new image. This function requires
a minimum of four tracking patterns. If there are not enough tracking patterns, new
tracking patterns are added until the total equals four.
 Perspective Positioning: This mode is the inverse of the Corner Positioning mode.
Rather than replacing the contents of the rectangle, the four trackers are mapped to the
four corners of the image. This is generally used to remove perspective from an image.
Like the Corner Positioning mode, this mode requires four tracking patterns, which
automatically get added if there are fewer patterns.
Additional Layering Controls
When you choose any operation other than None, a series of additional controls appear.
Merge
The Merge control determines what is done (if anything) with the image provided to the green
Foreground input of the Tracker. This menu appears when the operation is set to anything other
than None.
 BG Only: The foreground input is ignored; only the background is affected. This is used
primarily when stabilizing the background image.
 FG Only: The foreground input is transformed to match the movement in the
background, and this transformed image is passed through the Tracker’s output. This
Merge technique is used when match moving one layer’s motion to another layer’s
motion.
 FG Over BG: The foreground image is merged over the background image, using the
Merge method described by the Apply Mode control that appears.
 BG Over FG: The background is merged over the foreground. This technique is often
used when tracking a layer with an Alpha channel so that a more static background can
be applied behind it.
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