User Manual

Corner Positioning Operations
The Corner Positioning operation maps the four corners of a foreground image to four patterns
within the Tracker. This operation, or technique, is most commonly used for sign replacements.
The Corner Positioning operation of the Tracker requires the presence of a minimum of four
patterns. If this operation mode is selected and there are not four patterns set up in the Tracker
already, additional patterns will automatically be added to bring the total up to four.
When this mode is enabled, a set of drop-down boxes will appear to select which tracker
relates to each corner of the rectangle. It has no effect when the Merge control option is set
to BG Only.
Perspective Positioning Operations
The Perspective Positioning operation is used to remove perspective from a foreground image
or apply the perspective from one sequence to another. This can be useful when you need to
paint out an area that is distorted by perspective. Removing the perspective flattens the images
for painting, and then another tracker adds the perspective back.
The Perspective Positioning operation of the Tracker requires the presence of a minimum of
four patterns. If this operation mode is selected and there are not four patterns set up in the
Tracker already, additional patterns will automatically be added to bring the total up to four.
When this mode is enabled, a set of drop-down boxes will appear to select which tracker
relates to each corner of the rectangle. It has no effect when the Merge control option is set
to BG Only.
Connecting to Trackers’ Operations
One of the most common applications for a tracked pattern is using the tracked position or path
to drive the position of another node’s parameters. For example, tracking an eye in order to
color correct the eye to blue using an effect mask. You start off by tracking the eye, and then
create a color corrector with the desired settings. You create a mask in the shape of the eye
and connect the Tracker’s position to the Center of the mask.
In addition to the path (called Offset Position), each pattern in a tracker publishes four other
values for use as connections that are available to other nodes in the Node Editor.
You connect a node’s position parameters to a tracker by selecting the connection type from
the controls contextual menu (for example, Transform 1: Center > Connect To > Tracker 1 > Offset
Position).
There are five connection types automatically published by the tracker to connect to a position
parameter in another node.
Steady Position
Steady Position can be used to stabilize footage in both X and/or Y to remove camera shake
and other unwanted movement. The connection inverts the output of the tracked pattern’s
motion. When you connect a Center parameter to the Steady Position of the Tracker, it will be
placed at 0.5/0.5 (the center of the screen) by default at frame 1. You can change this using the
Reference mode in the Tracker’s Operation tab.
Chapter – 73 Using the Tracker Node 1506