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--- other:amass:documentation:track [2024/06/18 13:25] – sgranger
+++ other:amass:documentation:track [2024/07/17 15:44] (current) – created sgranger
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-===== Introduction =====
+====== Track ======
+==== Introduction ====
 The //**Track**// program accepts a .//cen// file, the Tracking parameters, and a .//cal// file, and runs without any user intervention to produce a .//seg// file containing three-dimensional __segments__ reconstructed from the image data. A __segment__ is a 3D trajectory of __points__ extending over multiple frames that is reconstructed from image data, and it may or may not represent an actual marker.
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 The ability of the //**Track**// program to reliably identify rays that belong to the same marker is strongly dependent upon the accuracy of the calibration. Rays that do not tightly intersect (have high residuals) cannot reliably be assigned to a single marker, resulting in poor tracking, “ghost markers” (caused by the program combining rays that actually come from different markers), and gaps in the marker segments. Hence, even if your experimental requirements do not call for high accuracy, the quality of the calibration is critical to effective marker trajectory generation.
-All marker (point) positions are expressed in the user distance units in the Global Coordinate System as defined by the [[Other:AMASS:Documentation:Calibrate#Reference_marker_file|reference markers]] during the system calibration.
+All marker (point) positions are expressed in the user distance units in the Global Coordinate System as defined by the [[Other:AMASS:Documentation:Calibrate_AMASS2#Reference_marker_file|reference markers]] during the system calibration.
-===== Track parameters =====
+==== Track parameters ====
 The Track parameters influence the 3D reconstruction and formation of the segments.
-{{track_params_nov3d.jpg}}
+{{:track_params_nov3d.jpg}}
   * ****Predictor error**** During tracking 3D point positions are gathered into trajectories or segments, and typically five previous frames of a point’s locations are used to predict its position in the next frame. The Predictor error parameter defines how far the point’s calculated location in the next frame may be from its predicted location in order for the point to be considered to belong to the current segment. If there are no points found within the **Predictor error** distance of the predicted location the segment is terminated. Setting this value too low will result in many short segments while setting it too high may cause segment crossovers (the trajectory of two markers are swapped). The default value is 5mm.The predictor error should be set with regard to
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   * ****Display frame**** Setting this Track parameter to a valid frame number will case the //**Track**// program to pause processing at the designated frame and allow the user to examine the marker reconstruction geometry. This facility is useful in diagnosing tracking problems and also serves as a very useful teaching tool. The graphics screen displays a 3D view of all rays, calculated marker locations, ray residuals, and predicted marker positions ( drawn to scale as squares), and allows image manipulation by use of the mouse. The markers are also drawn to scale according to the size entered in the **Marker diam.** parameter, and the small circles have a radius of 1.0 mm.
-{{sview.jpg}}
+{{:sview.jpg}}
 The view may be __rotated__ and __tilted__ by dragging with the __left__ mouse button. Dragging __up-down__ with the __right__ mouse button performs __zooming__ of the view, while __left-right__ dragging changes the __lengths of the rays__ that are displayed. __Right double-clicking__ on a marker makes that marker the __center__ of the display.
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-===== Tracking issues =====
+==== Tracking issues ====
-==== No segments produced ====
+=== No segments produced ===
 This condition is usually the result of tracking with an old calibration file that is no longer correct for your camera setup. Recalibrate your system often, and especially of any of the cameras have been disturbed.
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 Another possible cause might be the system renumbering of the cameras between the calibration and trial data captures. This condition could result from a system hardware reset, or the physical reconfiguring of the camera cable connections.
-==== Numerous short segments ====
+=== Numerous short segments ===
 The possible causes are
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 If you have a sufficient number of cameras, setting **Minimum cameras** to 3 will eliminate most artifacts resulting from reflections and false ray intersections.
-==== Segment crossovers ====
+=== Segment crossovers ===
 A segment crossover occurs when a segment from one marker gets connected to a segment of a different marker. This can happen when you use the **Connect gap** capability during tracking and that parameter is set too large. If this is an issue, set **Connect gap** to zero to turn off the connecting utility. Using **Segment trim** may also be very helpful.
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 It is also possible to get segment crossovers within a segment if the **Predictor error** is too large. The **Predictor error** value should always be less than the minimum separation of any markers.
-==== Missing frames during capture ====
+=== Missing frames during capture ===
 In some situations the //**Capture2D**// program may drop frames during camera data capture, especially if you are collecting data at high frame rates from many cameras. The situation can be complicated by other software that is also running on the data capture computer. Refer to the [[Other:Capture2D:Documentation|//**Capture2D**// documentation]] for recommendations.