There are four buttons used to initiate tracking, and one in the middle used to stop a track in progress. These buttons can track the current pattern forward or backward in time. Hold the mouse pointer over each button for a moment and a tooltip with the name of the button will appear.

The buttons operate as follows :

Clicking on this button will cause all Active trackers to begin tracking their patterns, starting at the end of the render range and moving backward through time until the beginning of the render range.

Clicking on this button will cause all Active trackers to begin tracking their patterns, starting at the current frame and moving backward through time until the beginning of the render range.

Clicking on this button will Stop the tracking process immediately. This can also be achieved by pressing ESC. This button will only be active when tracking is in process.

Clicking on this button will cause all Active trackers to begin tracking their patterns, starting at the current frame and moving forward through time until the end of the render range.

Clicking on this button will cause all Active trackers to begin tracking their patterns, starting at the first frame in the render range and moving forward through time until the end of the render range.

This value of the slider determines how often the Tracker sets a Keyframe on the Path. The normal default is 1, which sets a Keyframe on the tracked path at every frame. Increasing the value of this slider will cause the tracked path to be less accurate. This may be desirable if the track is returning fluctuating results, but under normal circumstances this control should be left at its default value.

Fusion is capable of re-acquiring the tracked pattern as needed, to help with complex tracks. This button array determines what mode of Adaptive tracking is employed.

If selected, Fusion searches only for the pattern originally selected in each single frame.

If selected, Fusion re-acquires the pattern every frame. This helps the tracker compensate for gradual changes in profile and lighting over time.

If selected, the Tracker will compare the pattern acquired at each frame and compare it to the original selected pattern. If the variation between the two patterns exceeds the threshold amount defined by the Match Tolerance control, Fusion will not re-acquire the pattern on that frame. This helps to avoid tracker drift caused by transient artifacts that cross the pattern's path (such as a shadow).

The two buttons in this button array determine how the Tracker behaves when re-positioning a pattern. These controls are used when switching a path from one pattern to another, which happens when a pattern leaves the frame, or changes so significantly it can no longer be tracked.

When Pattern Center is the Active mode, the tracked path continues from the center of the new path. This is appropriate when replacing an existing path entirely, but when trying to append to a path using a new pattern, this will cause a discontinuity.

When Track Center (append) is selected, the path tracked by a new pattern will be appended to the existing path. The Path created is automatically offset by the required amount. This technique will work best if the new pattern is located close to the position of the old pattern to avoid any problems with parallax or lens distortion. This mode can also be used to virtually continue the tracking of patterns that move out of the frame or get obstructed by other objects.

Use these to add or delete Trackers from your Tracker List.

Add a new Tracker

Delete the tracker that is currently selected in the Tracker List.

The Tracker List shows the names of all of the patterns created on this tracker. It is also used to add new trackers. The Tracker tool is capable of hosting a virtually unlimited number of tracker patterns.

Click on the Add button immediately above the list to add a new tracker pattern. Each pattern appears in the list by name, next to a small checkbox. Clicking on the name of the pattern will select that pattern. The controls below the list will change to affect that pattern only. Click once on a selected pattern to rename the pattern to something more descriptive. Clicking on the checkbox changes the state of the Tracker.

(Black Checkbox)

An Enabled pattern will re-track each time the track is initiated. Its path data is available for use by other tools, and the data is available for Stabilization and Corner Positioning.

(Grey Checkbox)

A Suspended pattern does not re-track when the track is initiated. The data is locked to prevent additional changes. The data from the Path is still available for other tools, and the data is available for advanced tracking modes like Stabilization and Corner Positioning.

(Clear)

A Disabled pattern does not create a path when tracking is initialized, and its data is not available to other tools, or for advanced tracking operations like Stabilization and Corner Positioning.

These two buttons determine what controls are displayed in the tool controls. They have no effect on the operation of the Tracker, they only affect the interface.

When Selected Tracker Details is selected, the controls displayed pertain only to the currently selected tracker. You will have access to the Pattern Window and the Offset sliders.

When All Trackers is selected, the pattern window for each of the trackers is displayed simultaneously below the Tracker List.

Pattern Display : Selected Pattern

The Pattern Display has two image windows next to each other, and a series of status bars. The window on the left shows the pattern initially selected, while the one on the right shows a real-time display of the current pattern as tracking progresses.

As the onscreen controls are moved for a pattern, the display in the leftmost window will update to show the pattern. As the pattern is moved, the clarity and contrast of the image channels is indicated by the vertical bars immediately to the right of the image display.

The channel, or channels, with the best clarity are automatically selected for tracking. These channels have a white background in the vertical bar representing that channel. The automatic tracking can be allowed to stand, or you can override the automatic selection and choose the channel used for tracking by disabling the button labelled with a question mark, and selecting the button beneath the channel to track.

Under normal circumstances, the channel selected is indicated in the Pattern Display. If the selected channel is blue, then a greyscale representation of the blue channel for the pattern appears. The image is only represented in full color if all three channels are selected for tracking.

Override this behavior by selecting the Show Full Color button beneath the Pattern Display, instead of the Show Selected Channel button.

The Pattern Display on the right indicates the actual pattern acquired for tracking. This display is clear until the first time the selected pattern is actually tracked. The Pattern Display becomes active during tracking, displaying the pattern that Fusion acquires from frame to frame.

As the tracking occurs, the pattern from each frame is accumulated into a Flipbook, which can be played back in the pattern window after tracking by using the transport controls at the bottom of the window.

While the track is progressing, the vertical bar immediately to the right of the pattern shows how confident Fusion is that the current pattern matches the originally selected pattern. A green bar indicates a high degree of confidence that the current pattern matches the original. A yellow bar indicates less certainty, and a red bar indicates that Fusion has detected extreme variations in the current pattern, and is no longer certain of its accuracy.

After tracking, the pattern display will show a small flipbook of the track for that pattern, overlaid with a frame number to help identify problem frames for the track

Use these controls to adjust the width and height of the selected tracker pattern manually. The size of the tracker pattern can also be adjusted in the display view, which is the normal method, but small adjustments are often easier to accomplish with the precision of manual controls.

The search area defines how far Fusion will look in the image from frame to frame to re-acquire the pattern during tracking. As with the Pattern Width and Height, the Search Area can be adjusted in the display views, but you may want to make small adjustments manually using these controls.

This positional control indicates the position of the tracker's center. To remove a path from a tracker pattern, right-click on this control and select Remove Path from the context menu.

You will often need to track the position of an object in the scene, but that object does not provide for a very reliable pattern. The Offsets permit the tracking of something close to the intended object instead. Use these Offsets to adjust the reported position of the Tracker so that the data is reported for the intended pattern instead of the actual one. File:F6 Tool Tracker Icon Offset.png
The Offset can also be adjusted directly in the view by activating the "allow moving the positioner's offsets" icon next to your view.

The Tracker tool is capable of performing a wide variety of functions, from match moving an object into a moving scene, smoothing out in 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 tool.

Please also refer to the Tracking Explained section in the Appendices.

These four buttons select the exact function performed by the Tracker. The remaining controls in this tab fine tune the result of the Operation.

The Tracker performs no additional operation on the image beyond simply locating and tracking the chosen pattern. This is the default mode, used to create a path that will then drive another control in Fusion.

This mode is used when stabilizing an image, or when matching the position, rotation and scaling of the layer for match moving another element into the scene. Stabilizing requires a minimum of one tracker to determine position, and two or more to determine scaling and rotation in the sequence.

The Corner Positioning mode is used to track the four corners of a rectangular object, and replace the contents with a new image. A minimum of four trackers is required for this mode, and if there are not enough trackers, new ones will be created until the total equals four.

This mode is similar to the Corner Positioner but, rather than replacing the contents of the rectangle, the four tracked corners are mapped to the four corners of the image. This is generally used to remove Perspective from an image. Like the Corner Positioner, this mode requires four trackers, which will be created if there are not already that many.

The Merge control determines what is done (if anything) with the image provided to the foreground input of the Tracker. This array of buttons appears when the operation is set to anything other than None.

The foreground input is ignored, only the Background is affected. This is used primarily when Stabilizing an image sequence.

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's.

The Foreground image is merged over the Background image, using the Merge method described by the Apply Mode control that appears.

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.

This drop-down menu provides a variety of options to determine how the two layers should be combined. The options in this menu are explained in more detail in the reference chapter for the Merge tool.

This determines whether the foreground layer is placed over the background in using Additive or Subtractive merging techniques. This control is explained in more detail in the documentation for the Merge tool.

This button array only appears if the Operation mode is set to Match Move. The various options select how the revealed edges are handled when the image is moved to match position and scaling.

Out of frame edges revealed by Stabilization are left black.

Portions of the image moved off frame to one side are used to fill edges that are revealed on the opposite side.

The last valid pixel on an edge is repeated to the edge of the frame.

The Position, Rotation and Scaling checkboxes only appear when the mode is set to Match Move. They determine what components of motion that stabilization will attempt to correct in the image. For example, if only the Position checkbox is selected, no attempt will be made to correct for Rotation and Scaling in the image.

This checkbox only appears when the mode is set to Match Move. Like most transformations in Fusion, Stabilization is concatenated with other sequential transformations by default. Selecting this checkbox will flatten the transform, breaking any concatenation taking place and applying the transform immediately.

The Mapping Type control only appears in the Corner Positioning mode. There are two options in the button array.

The first method is Bi-Linear where the FG image is mapped into the BG without any attempt to correct for perspective distortion. This is identical to how previous versions of Fusion operated, and the Classic mode is included pretty much for compatibility reasons only.

The preferred setting for this control is True Perspective.

When the operation of the Tracker is set to either Corner or Perspective Positioner modes, these four drop-down menus appear. They are used to select which trackers map to each of the four corners of the rectangle used by these modes. This is useful when a tracker has more than four patterns selected, and you must choose which are used by the positioners.

These controls only appear when the operation of the Tracker is set to either Corner or Perspective Positioner modes. They are used to rotate the FG image by 90 degrees before it is applied to the BG.

The Tracker tool automatically outputs several steady and unsteady position outputs to which other controls in the Flow can be connected. The Stable Position output provides X and Y coordinates to match or reverse motion in a sequence. These controls are available even when the operation is not set to Match Move, since the Stable Position output is always available for connection to other tools.

See the Tracking page for details.

Under virtually all circumstances, the axis for any stabilization should be the average position of all trackers on that frame, however, the rare occasion arises when the tracker's axis must be elsewhere.

This array of buttons allows for the selection of an axis for the Stabilization based on the position of a single tracker, or a manual position.

The Reference controls are used to set the `snapshot frame' for Stabilization. When you stabilize an image, there must be a position that is considered correct, to which all subsequent movement is detected, and corrected.

The Select Time Reference mode determines the `snapshot frame' based on the frame where the pattern is first selected. All Stabilization is intended to return the image back to that reference.

The snapshot frame is determined to be the first frame in the tracked path. All Stabilization is intended to return the image back to that reference.

The Start and End Reference mode is somewhat different from all other Reference modes. Where the others are intended to take a snapshot frame to which all stabilization returns, immobilizing the image, the Start and End mode is intended to smooth existing motion, without removing it. This mode averages the motion between the Start and End of the path, drawing a straight line between those points.

When this mode is Active, it reveals the Reference Intermediate Points control. Increasing the value of this control increases the number of points in the path used by the Reference, smoothing the motion from a straight line between start and end without making it wholly linear.

The snapshot frame is determined to be the last frame in the tracked path. All Stabilization is intended to return the image back to that Reference.

Each pattern in the tracker has its own set of onscreen controls, used to select the pixels in the image to be tracked. These controls are visible in the display views whenever a tracker is selected in a flow.

The onscreen control is indicated by a red rectangle with a handle in the top left corner. This rectangle indicates the position of the pattern in the image. Every pixel within the rectangle is considered to be part of the pattern used for tracking. Resize the pattern by clicking and dragging on the rectangles borders.

Whenever the mouse moves over the pattern rectangle, a second rectangle with a dashed outline appears. This represents the search area, which determines how far away from the current pattern the Tracker looks on the next frame. This should always be larger than the pattern, and it should be large enough to encompass the largest frame-to-frame movement in the scene. Faster moving objects require larger search areas and slower moving objects can get away with smaller search areas. The larger the search area, the longer it will take to track, so try not to make the search area larger than necessary.

Click-dragging on the handle repositions the pattern. While repositioning the pattern, a thumbnail window with an enlarged view of the pattern is displayed in the views, to assist with precise positioning of the pattern. This thumbnail disappears when the mouse button is released. The magnification ratio can be adjusted in the options tab. If the selected tracker has a custom name, the name of that tracker will be displayed as a label at the bottom right of the search area rectangle.

This option defines if the Tracker's name will be displayed in the view. Switch it off to see just the Pattern Rectangle instead.

This option defines if there is an enlarged view on positioning the Pattern Rectangle or not.

The Zoom factor that is used on positioning the Pattern Rectangle when the above option is on.