Data Export: CSV
Last updated
Last updated
Captured tracking data can be exported in Comma Separated Values (CSV) format. This file format uses comma delimiters to separate multiple values in each row, and it can be imported by spreadsheet software or a programming script. Depending on which data export options are enabled, exported CSV files can contain marker data, Rigid Body data, and/or Skeleton data. CSV export options are listed in the following charts:
General Export Options
| Option | Description |
|---|---|
CSV Export Options
| CSV Options | Description |
|---|---|
Rigid Body markers or Skeleton bone markers are referred to as Marker Constraints. They appear as transparent spheres within a Rigid Body, or a Skeleton, and each sphere reflect the position that a Rigid Body, or a Skeleton, expects to find a 3D marker. When the asset definitions are created, it is assumed that the markers are fixed at the same location and do not move over the course of capture.
In the CSV file, Rigid Body markers have a physical marker column and a Marker Constraints column. They have nearly the same ID but are distinguished by the first 8 characters as uniquely identifiable.
When a marker is occluded in Motive, the Marker Constraints will display the last known position of where it thinks the marker should be in the CSV file. The actual physical marker will display a blank cell or null value since Motive cannot account for its actual location due to its occlusion.
When the header is disabled, this information will be excluded from the CSV files. Instead, the file will have frame IDs in the first column, time data on the second column, and the corresponding mocap data in the remaining columns.
CSV Headers
TIP: Occlusion in the marker data
When there is an occlusion of a marker, the CSV file will contain blank cells. This can interfere when running a script to process the CSV data. It is recommended to optimize the system setup to reduce occlusions. To omit unnecessary frame ranges with frequent marker occlusions, select the frame range with the most complete tracking results. Another solution to this is to use Fill Gaps to interpolate missing trajectories in post-processing.
For Takes containing force plates (AMTI or Bertec) or data acquisition (NI-DAQ) devices, additional CSV files will be exported for each connected device. For example, if you have two force plates and a NI-DAQ device in the setup, a total 4 CSV files will be created when you export the tracking data from Motive. Each of the exported CSV files will contain basic properties and settings in its header (if Header Information is selected), including device information and sample counts. Also, the mocap frame rate to device sampling rate ratio is included since force plate and analog data are sampled at higher sampling rates.
Since device data is usually sampled at a higher rate than the camera system, the camera samples are collected at the center of the corresponding device data samples. For example, if the device data has 9 sub-frames for each camera frame sample, the camera tracking data will be recorded at every 5th frame of device data.
Force Plate Data: Each of the force plate CSV files will contain basic properties such as platform dimensions and mechanical-to-electrical center offset values. The mocap frame number, force plate sample number, forces (Fx/Fy/Fz), moments (Mx, My, Mz), and location of the center of pressure (Cx, Cy, Cz) will be listed below the header.
Analog Data: Each of the analog data CSV files contains analog voltages from each configured channel.
| Row | Description |
|---|---|
Frame Rate
Number of samples included per every second of exported data.
Start Frame
Start frame of the exported data. You can either set it to the recorded first frame of the exported Take or to the start of the working range, or scope range, as configured under the Control Deck or in the Graph View pane.
End Frame
End frame of the exported data. You can either set it to the recorded end frame of the exported Take or to the end of the working range, or scope range, as configured under the Control Deck of in the Graph View pane.
Scale
Apply scaling to the exported tracking data.
Units
Sets the length units to use for exported data.
Axis Convention
Sets the axis convention on exported data. This can be set to a custom convention, or preset convetions for exporting to Motion Builder or Visual3D/Motion Monitor.
X Axis Y Axis Z Axis
Allows customization of the axis convention in the exported file by determining which positional data to be included in the corresponding data set.
Markers
Enabling this option includes X/Y/Z reconstructed 3D positions for each marker in exported CSV files.
Unlabeled Markers
Enableing this option includes tracking data of all of the unlabeled makers to the exported CSV file along with other labeled markers. If you just want to view the labeled marker data, you can turn off this export setting.
Rigid Bodies
When this option is set to true, exported CSV file will contain 6 Degree of Freedom (6 DoF) data for each rigid body from the Take. 6 DoF data contain orientations (pitch,roll, and yaw in the chosen rotation type as well as 3D positions (x,y,z) of the rigid body center.
Rigid Body Markers
Enabling this option includes 3D position data for each Marker Constraints locations (not actual marker location) of rigid body assets. Compared to the positions of the raw marker positions included within the Markers columns, the Rigid Body Markers show the solved positions of the markers as affected by the rigid body tracking but not affected by occlusions.
Bones
When this option is set to true, exported CSV files will include 6 DoF data for each bone segment of skeletons in exported Takes. 6 DoF data contain orientations (pitch, roll, and yaw) in the chosen rotation type, and also 3D positions (x,y,z) for the center of the bone.
Bone Markers
Enabling this option will include 3D position data for each Marker Constraints locations (not actual marker location) of bone segments in skeleton assets. Compared to the real marker positions included within the Markers column, the Bone Markers show the solved positions of the markers as affected by the skeleton tracking but not affected by occlusions.
Header information
Includes detailed information about capture data as a header in exported CSV files. Types of information included in the header section is listed in the following section.
Rotation Type
Rotation type determines whether Quaternion or Euler Angles are used for orientation convention in exported CSV files. For Euler rotation, right-handed coordinate system is used and all different orders (XYZ, XZY, YXZ, YZX, ZXY, ZYX) of elemental rotation are available. More specifically, the XYZ order indicates pitch is degree about the X axis, yaw is degree about the Y axis, and roll is degree about the Z axis.
Device Data
When set to True, separate CSV files for recorded device data will be exported. This includes force plate data and analog data from NI-DAQ devices. A CSV file will be exported for each device included in the Take.
Use World Coordinates
This option decides whether exported data will be based on world (global) or local coordinate systems.
Global: Defines the position and orientation in respect to the global coordinate system of the calibrated capture volume. The global coordinate system is the origin of the ground plane which was set with a calibration square during the Calibration process.
Local: Defines the bone segment position and orientation in respect to the coordinate system of the parent segment. Note that the hip of the skeleton is always the top-most parent of the segment hierarchy. Local coordinate axes can be set to visible from Application Settings or in the skeleton properties. The Bone segment rotation values in the Local coordinate space can be used to roughly represent the joint angles, however, for precise analysis, joint angles should be computed through a biomechanical analysis software using the exported capture data (C3D).
1st row
General information about the Take and export settings. Included information are: format version of the CSV export, name of the TAK file, the captured frame rate, the export frame rate, capture start time, number of total frames, rotation type, length units, and coordinate space type.
2nd row
Empty
3rd row
Displays which data type is listed in each corresponding column. Data types include raw marker, Rigid Body, Rigid Body marker, bone, bone marker, or unlabeled marker. Read more about Marker Types.
4th row
Includes marker or asset labels for each corresponding data set.
5th row
Displays marker ID.
6th and 7th row
Shows which data is included in the column: rotation or position and orientation on X/Y/Z.
