TARGET Data Type
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In Visual3D motion capture data (e.g. 3D markers) are stored in the Data Tree as a TARGET Data type. A TARGET is a 3 degree of freedom signal. TARGET information is either specified in a C3D file, or another file format that has been translated into a C3D file during the process of importing the file. TARGETS contain 5 elements, but Visual3D currently displays only 4 of these elements: (x,y,z) components describe the location of the point in 3D space; and the residual component contains information from the motion capture hardware indicating the reliability of the point.
TARGET::ORIGINAL
The ORIGINAL folder contains the POINT data that was stored in the C3D File.
The POINT data contains 5 components: x, y , z, residual, and camera contribution
Note: Visual3D does not routinely let you modify the signals in this folder.
Target Marker Position
This is the x,y,z position of the marker in space.
Target Marker Residual
This is the residual error computed by the data collection software. This can be treated as the reliability in reconstructing the 3D position of the marker. Marker reliability is a measure of the accuracy of the 3D motion capture system in locating a marker. Each camera in the motion capture system identifies a ray from the camera to the marker. In an ideal world the ray from all cameras would converge on the center of the marker, but the world isn't ideal. The residual is a measure of the size of a sphere that contains the point at which all rays were closest to the marker. In other words, big residuals indicate that the motion capture system could not reliably locate the marker.
A reliability of -1 indicates that the point was obscured or could not be localized by the mocap system. A reliability of 0 indicates that the file was processed (by some unknown process, such as a filter or interpolation). A reliability>0 is an indication of the accuracy of the point.
Camera Contribution
A 7 bit value containing the numbers of the cameras that were used for the reconstruction. This is a legacy value because if only allows data from 7 cameras, so Visual3D doesn't bother displaying the contents.