Eyeon:Manual/Fusion 6/TrackingExplained
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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.
If the project is field rendered, a value of 1 sets a Keyframe on every field. Since the tracker is extremely accurate, this will result in a slight up-and-down jittering due to the position of the tracked pattern fields. For fielded footage tracked in field mode you will get better results setting this slider to a value of 2, which will result in one keyframe per frame of your footage.
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.
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.
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.
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.
As Fusion looks for the channel with the highest contrast automatically, you might end up tracking the boue channel, especially on scanned film material. Unfortunately the blue channel on most filmstock contains the most grain as well, which naturally leads to unclean tracks. Before tracking it's always a good idea to zoom into your footage and check the RGB channels individually.
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.
Tips for TrackingExplained (edit)
EyeonTips:Manual/Fusion 6/TrackingExplained
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