Marker Tracking System

Establishes a dynamic local coordinate system based on one or two tracing markers.



Figure 1.

When a marker is traced, the coordinates of the marker can be reported with respect to the tracking system defined in this panel. This enables you to calculate only the dynamics of marker movement by removing overall motion of the video.

The user-defined coordinate system is displayed in the graphics area with arrows of the selected colors to represent the X and Y axes.

Collectors
Use the Origin collector to select the marker to be used as the origin.
Use the X/Y Axis collector to select the marker that designates the axis (relative to the origin).
Click to switch between the X and Y axis.
Only one collector can be active at a time. Once the first set of coordinates has been selected for the Origin collector, the Axis selector becomes active.
Start Time
End Time
Two start and end time fields exist:
  • The start time and end time for the origin marker, showing the start and end time steps in the video during which the marker is valid.
  • The start time and end time for the X axis or Y axis marker, showing the start and end time steps in the video during which the marker is valid.
Valid Time Range
The time range during which the defined tracking system is valid. Since both markers must be valid in order for the system to be valid at a given time, the start time will always be the latter of the selected markers’ start times, and the end time will always be the earlier of the selected markers’ end times.
Animation Control Time Range
The time range shown by the start and end times in the Animation Controls panel, and can be synced to the valid time range using Sync Range.
Sync Range
Syncs the Animation Controls time range to the tracking system’s valid time range. Click Sync Range to update the start time and end time edit fields for the Animation Controls Time Range and also to update the start and end times in the Animation Controls panel.
Use tracking system
This option is disabled by default, and is enabled and automatically selected once a tracking system has been defined. When off, marker tracing data is reported with the origin assumed to be in the lower left corner of the video.
Pin video at origin
This option will cause the origin to remain fixed in place on the screen while animating, during the time frame when the origin is a valid tracing marker.
Global X axis
Click the color selector to select the x-axis color.
Global Y axis
Click the color selector to select the y-axis color.
Axis Labels
Click the color selector to select the axis labels’ colors.
Note: When tracking with respect to the user-defined system, the locations of all markers are reported in terms of the user-defined coordinate system.  The markers used as the bases for the coordinate system appear as static values of (0, 0) for the origin at CS point 1, and (0, <pixels or units>) or (<pixels or units>, 0) for the marker at CS point 2.