Tracking data can be exported into the C3D file format. C3D (Coordinate 3D) is a binary file format that is widely used especially in biomechanics and motion study applications. Recorded data from external devices, such as force plates and NI-DAQ devices, will be recorded within exported C3D files. Note that common biomechanics applications use a Z-up right-hand coordinate system, whereas Motive uses a Y-up right-hand coordinate system. More details on coordinate systems are described in the later section. Find more about C3D files from https://www.c3d.org.
General Export Options
| Option | Description |
|---|---|
C3D Specific Export Options
| Options | Descriptions |
|---|---|
Common Conventions
Since Motive uses a different coordinate system than the system used in common biomechanics applications, it is necessary to modify the coordinate axis to a compatible convention in the C3D exporter settings. For biomechanics applications using z-up right-handed convention (e.g. Visual3D), the following changes must be made under the custom axis.
X axis in Motive should be configured to positive X
Y axis in Motive should be configured to negative Z
Z axis in Motive should be configured to positive Y.
This will convert the coordinate axis of the exported data so that the x-axis represents the anteroposterior axis (left/right), the y-axis represents the mediolateral axis (front/back), and the z-axis represents the longitudinal axis (up/down).
MotionBuilder Compatible Axis Convention
This is a preset convention for exporting C3D files for use in Autodesk MotionBuilder. Even though Motive and MotionBuilder both use the same coordinate system, MotionBuilder assumes biomechanics standards when importing C3D files (negative X axis to positive X axis; positive Z to positive Y; positive Z to positive Y). Accordingly, when exporting C3D files for MotionBuilder use, set the Axis setting to MotionBuilder Compatible, and the axes will be exported using the following convention:
Motive: X axis → Set to negative X → Mobu: X axis
Motive: Y axis → Set to positive Z → Mobu: Y axis
Motive: Z axis → Set to positive Y → Mobu: Z axis
There is an known behavior where importing C3D data with timecode doesn't accurately show up in MotionBuilder. This happens because MotionBuilder sets the subframe counts in the timecode using the playback rate inside MotionBuilder instead of using the rate of the timecode. When this happens you can set the playback rate in MotionBuilder to be the same as the rate of the timecode generator (e.g. 30 Hz) to get correct timecode. This happens only with C3D import in MotionBuilder, FBX import will work fine without the change to the playback rate.
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.
Use Zero Based Frame Index
C3D specification defines first frame as index 1. Some applications import C3D files with first frame starting at index 0. Setting this option to true will add a start frame parameter with value zero in the data header.
Export Unlabeled Markers
Includes unlabeled marker data in the exported C3D file. When set to False, the file will contain data for only labeled markers.
Export Finger Tip Markers
Includes virtual reconstructions at the finger tips. Available only with Skeletons that support finger tracking (e.g. Baseline + 11 Additional Markers + Fingers (54))
Use Timecode
Includes timecode.
Rename Unlabeled As _000X
Unlabeled markers will have incrementing labels with numbers _000#.
Marker Name Syntax
Choose whether the marker naming syntax uses ":" or "_" as the name separator. The name separator will be used to separate the asset name and the corresponding marker name in the exported data (e.g. AssetName:MarkerLabel or AssetName_MarkerLabel or MarkerLabel).
Captured tracking data can be exported into a Track Row Column (TRC) file, which is a format used in various mocap applications. Exported TRC files can also be accessed from spreadsheet software (e.g. Excel). These files contain raw output data from capture, which include positional data of each labeled and unlabeled marker from a selected Take. Expected marker locations and segment orientation data are not be included in the exported files. The header contains basic information such as file name, frame rate, time, number of frames, and corresponding marker labels. Corresponding XYZ data is displayed in the remaining rows of the file.
Motive can export tracking data in BioVision Hierarchy (BVH) file format. Exported BVH files do not include individual marker data. Instead, a selected skeleton is exported using hierarchical segment relationships. In a BVH file, the 3D location of a primary skeleton segment (Hips) is exported, and data on subsequent segments are recorded by using joint angles and segment parameters. Only one skeleton is exported for each BVH file, and it contains the fundamental skeleton definition that is required for characterizing the skeleton in other pipelines.
Notes on relative joint angles generated in Motive: Joint angles generated and exported from Motive are intended for basic visualization purposes only and should not be used for any type of biomechanical or clinical analysis.
General Export Options
| Option | Description |
|---|
BVH Specific Export Options
| Option | Description |
|---|
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:
| CSV Options | Description |
|---|
The quality stats display the reliability of associated marker data. Errors per marker lists average displacement between detected markers and expected marker locations within corresponding assets. Marker Quality values rate how well camera rays converged when the respective marker was reconstructed. The value varies from 0 (unstable marker) to 1 (accurate marker).
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
Please note that device data is usually sampled at a higher rate then the camera system. In this case, camera samples are collected at the center of the device data samples that were collected in this period. For example, if device data has 9 sub-frame for each camera frame sample, the tracking data will be at every 5th 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.
A Motive Body license can export tracking data into FBX files for use in other 3D pipelines. There are two types of FBX files: Binary FBX and ASCII FBX.
Notes for MotionBuilder Users
When exporting tracking data onto the MotionBuilder in FBX file format, make sure the exported frame rate is supported in MotionBuilder (Mobu). In Mobu, there is a select set of playback frame rate that's supported, and rate of the exported FBX file must agree in order to playback the data properly.
If there is a non-standard frame rate selected that is not supported, the closest supported frame rate is applied.
Exported FBX files in ASCII format can contain reconstructed marker coordinate data as well as 6 Degree of Freedom data for each involved asset depending on the export setting configurations. ASCII files can also be opened and edited using text editor applications.
FBX ASCII Export Options
Binary FBX files are more compact than ASCII FBX files. Reconstructed 3D marker data is not included within this file type, but selected Skeletons are exported by saving corresponding joint angles and segment lengths. For Rigid Bodies, positions and orientations at the defined Rigid Body origin are exported.
FBX Binary Export Options
Various types of files, including the tracking data, can be exported out from Motive. This page provides information on what file formats can be exported from Motive and instructions on how to export them.
Once captures have been recorded into Take files and the corresponding 3D data have been reconstructed, tracking data can be exported from Motive in various file formats.
Exporting Rigidbody Tracking Data
If the recorded Take includes Rigid Body trackable assets, make sure all of the Rigid Bodies are Solved prior to exporting. The solved data will contain positions and orientations of each Rigid Body.
In the export dialog window, the frame rate, the measurement scale, and the frame range of exported data can be configured. Additional export settings are available for each export file formats. Read through below pages for details on export options for each file format:
Exporting a Single Take
Step 3. On the export dialogue window, select a file format and configure the corresponding export settings.
To export the entire frame range, set Start Frame and End Frame to Take First Frame and Take Last Frame.
To export a specific frame range, set Start Frame and End Frame to Start of Working Range and End of Working Range.
Step 4. Click Save.
Working Range:
The working range (also called the playback range) is both the view range and the playback range of a corresponding Take in Edit mode. Only within the working frame range will recorded tracking data be played back and shown on the graphs. This range can also be used to output specific frame ranges when exporting tracking data from Motive.
The working range can be set from the following places:
In the navigation bar of the Graph View pane, you can drag the handles on the scrubber to set the working range.
Exporting Multiple Takes
Step 2. Right-click on the selected Takes and click Export Tracking Data from the context menu.
Step 3. An export dialogue window will show up for batch exporting tracking data.
Step 4. Select the desired output format and configure the corresponding export settings.
Step 5. Select frame ranges to export under the Start Frame and the End Frame settings. You can either export entire frame ranges or specified frame ranges on all of the Takes. When exporting specific ranges, desired working ranges must be set for each respective Takes.
To export entire frame ranges, set Start Frame and End Frame to Take First Frame and Take Last Frame.
To export specific frame ranges, set Start Frame and End Frame to Start of Working Range and End of Working Range.
Step 6. Click Save.
Motive Batch Processor:
Motive exports reconstructed 3D tracking data in various file formats and exported files can be imported into other pipelines to further utilize capture data. Available export formats include CSV, C3D, FBX, BVH, and TRC. Depending on which options are enabled, exported data may include reconstructed marker data, 6 Degrees of Freedom (6 DoF) Rigid Body data, or Skeleton data. The following chart shows what data types are available in different export formats:
CSV and C3D exports are supported in both Motive Tracker and Motive Body licenses. FBX, BVH, and TRC exports are only supported in Motive Body.
Recorded NI-DAQ analog channel data can be exported into C3D and CSV files along with the mocap tracking data. Follow the tracking data export steps outlined above and any analog data that exists in the TAK will also be exported.
When an asset definition is exported to a MOTIVE user profile, it stores marker arrangements calibrated in each asset, and they can be imported into different takes without creating a new asset in Motive. Note that these files specifically store the spatial relationship of each marker, and therefore, only the identical marker arrangements will be recognized and defined with the imported asset.
To export the assets, go to the File menu and select Export Assets to export all of the assets in the Live-mode or in the current TAK file(s). You can also use File → Export Profile to export other software settings including the assets.
Recorded NI-DAQ analog channel data can be exported into C3D and CSV files along with the mocap tracking data. Follow the tracking data export steps outlined above and any analog data that exists in the TAK will also be exported.
CSV Export: When exporting tracking data into CSV, additional CSV files will be exported for each of the NI-DAQ devices in a Take. Each of the exported CSV files will contain basic properties and settings at its header, including device information and sample counts. The voltage amplitude of each analog channel will be listed. Also, mocap frame rate to device sampling ratio is included since analog data is usually sampled at higher sampling rates.
Note
The coordinate system used in Motive (y-up right-handed) may be different from the convention used in the biomechanics analysis software.
Common Conventions
Since Motive uses a different coordinate system than the system used in common biomechanics applications, it is necessary to modify the coordinate axis to a compatible convention in the C3D exporter settings. For biomechanics applications using z-up right-handed convention (e.g. Visual3D), the following changes must be made under the custom axis.
X axis in Motive should be configured to positive X
Y axis in Motive should be configured to negative Z
Z axis in Motive should be configured to positive Y.
This will convert the coordinate axis of the exported data so that the x-axis represents the anteroposterior axis (left/right), the y-axis represents the mediolateral axis (front/back), and the z-axis represents the longitudinal axis (up/down).
Reference Video Type: Only compressed MJPEG reference videos can be recorded and exported from Motive. Export for raw grayscale videos is not supported.
Media Player: The exported videos may not be playable on Windows Media Player, please use a more robust media player (e.g. VLC) to play the exported video files.
Sample Skeleton Label XML File
| Row | Description |
|---|
When there is an occlusion in 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 to interpolate missing trajectories in post-processing.
For Takes containing force plates ( or ) or data acquisition () 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, total 4 CSV files will be saved when you export the tracking data from Motive. Each of the exported CSV files will contain basic properties and settings at its header, including device information and sample counts. Also, mocap frame rate to device sampling rate ratio is included since force plate and analog data are sampled at higher sampling rates.
For more information, please visit site.
Autodesk has discontinued support for FBX ASCII import in MotionBuilder 2018 and above. For alternatives when working in MotionBuilder, please see the page.
| Options | Description |
|---|
| Options | Descriptions |
|---|
Step 1. Open and select a Take to export from the . The selected Take must contain reconstructed 3D data.
Step 2. Under the File tab on the command bar, click File → Export Tracking Data. This can also be done by right-clicking on a selected Take from the and clicking Export Tracking Data from the context menu.
You can also use the navigation controls on the Graph View pane to zoom in or zoom out on the frame ranges to set the working range. See: page.
Start and end frames of a working range can also be set from the when in the Edit mode.
Step 1. Under the , shift + select all the Takes that you wish to export.
Exporting multiple Take files with specific options can also be done through a script. For example, refer to FBXExporterScript.cs script found in the MotiveBatchProcessor folder.
| Tracking Data Type | CSV | C3D | FBX | BVH | TRC |
|---|
A calibration definition of a selected take can be exported from the Export Camera Calibration under the File tab. Exported calibration (CAL) files contain camera positions and orientations in 3D space, and they can be imported in different sessions to quickly load the calibration as long as the is maintained.
Read more about calibration files under the page.
C3D Export: Both mocap data and the analog data will be exported onto a same C3D file. Please note that all of the analog data within the exported C3D files will be logged at the same sampling frequency. If any of the devices are captured at different rates, Motive will automatically resample all of the analog devices to match the sampling rate of the fastest device. More on C3D files:
When there is an MJPEG reference camera in a Take, its recorded video can be exported into an AVI file or into a sequence of JPEG files. The Export Video option is located under the File tab or you can also right-click on a TAK file from the and export from there. At the bottom of the export dialog, the frame rate of the exported AVI file can be set to a full-frame rate or down-sampled to half, quarter, 1/8, or 1/16 ratio framerate. You can also adjust the playback speed to export a video with a slower or faster playback speed. The captured reference videos can be exported into AVI files using either H.264 or MJPEG compression format. The H.264 format will allow faster export of the recorded videos and is recommended. Read more about recording reference videos on page.
When a recorded capture contains audio data, an audio file can be exported through the Export Audio option that appears when right-clicking on a Take from the .
Skeletal marker labels for Skeleton assets can be exported as XML files (example shown below) from the . The XML files can be imported again to use the stored marker labels when creating new Skeletons.
For more information on Skeleton XML files, read through the page.
Reconstructed 3D Marker Data | • | • | • | • |
6 Degrees of Freedom Rigid Body Data | • | • | • |
Skeleton Data | • | • | • |
Frame Rate | Number of samples included per every second of exported data. |
Start Frame |
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. |
Markers | Enabling this option includes X/Y/Z reconstructed 3D positions for each marker in exported CSV files. |
Unlabeled Markers | Enabling 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. |
Quality Statistics | Adds a column of Mean Marker Error values for each rigid body position data. Adds a column of Marker quality values after each rigid body marker data. More details are provided in the below section. |
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. |
RigidBodyMarkers | Enabling this option includes 3D position data for each expected marker locations (not actual marker location) of rigid body assets. Compared to the positions of the reconstructed 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 proximal joint center of the bone which is the pivot point of the bone. |
BoneMarkers |
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 is 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 is 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. |
Unit | Sets units for positional data in exported CSV files |
Export 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. |
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 |
4th row | Includes marker or asset labels for each corresponding data set. |
5th row | Displays marker ID. |
6th and 7th row | Includes header label on which data is included in the column: position and orientation on X/Y/Z. |
Frame Rate | Number of samples included per every second of exported data. |
Start Frame |
End Frame |
Scale | Apply scaling to the exported tracking data. |
Units | Set the unit in exported files. |
Use Timecode | Includes timecode. |
Export FBX Actors | Includes FBX Actors in the exported file. Actor is a type of asset used in animation applications (e.g. MotionBuilder) to display imported motions and connect to a character. In order to animate exported actors, associated markers will need to be exported as well. |
Optical Marker Name Space | Overrides the default name spaces for the optical markers. |
Marker Name Separator | Choose ":" or "_" for marker name separator. The name separator will be used to separate the asset name and the corresponding marker name when exporting the data (e.g. AssetName:MarkerLabel or AssetName_MarkerLabel). When exporting to Autodesk Motion Builder, use "_" as the separator. |
Markers | Export each marker coordinates. |
Unlabeled Markers | Includes unlabeled markers. |
Calculated Marker Positions | Export asset's constraint marker positions as the optical marker data. |
Interpolated Fingertips | Includes virtual reconstructions at the finger tips. Available only with Skeletons that support finger tracking. |
Marker Nulls | Exports locations of each marker. |
Export Skeleton Nulls |
Rigid Body Nulls |
Frame Rate | Number of samples included per every second of exported data. |
Start Frame |
End Frame |
Scale | Apply scaling to the exported tracking data. |
Units | Sets the unit for exported segment lengths. |
Use Timecode | Includes timecode. |
Export Skeletons |
Skeleton Names | Names of Skeletons that will be exported into the FBX binary file. |
Name Separator | Choose ":" or "_" for marker name separator. The name separator will be used to separate the asset name and the corresponding marker name when exporting the data (e.g. AssetName:MarkerLabel or AssetName_MarkerLabel). When exporting to Autodesk Motion Builder, use "_" as the separator. |
Rigid Body Nulls |
Rigid Body Names | Names of the Rigid Bodies to export into the FBX binary file as 6 DoF nulls. |
Marker Nulls | Exports locations of each marker. |
Frame Rate | Number of samples included per every second of exported data. |
Start Frame |
End Frame |
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. |
Single Joint Torso | When this is set to true, there will be only one skeleton segment for the torso. When set to false, there will be extra joints on the torso, above the hip segment. |
Hands Downward | Sets the exported skeleton base pose to use hands facing downward. |
MotionBuilder Names | Sets the name of each skeletal segment according to the bone naming convention used in MotionBuilder. |
Skeleton Names | Set this to the name of the skeleton to be exported. |
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 or in the .
Enabling this option will include 3D position data for each (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.
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 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 or display properties of assets in . 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).
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 .
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 or in the .
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 of in the .
Can only be exported when is recorded for exported Skeleton assets. Exports 6 Degree of Freedom data for every bone segment in selected Skeletons.
Can only be exported when is recorded for exported Rigid Body assets. Exports 6 Degree of Freedom data for selected Rigid Bodies. Orientation axes are displayed on the geometrical center of each Rigid Body.
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 or in the .
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 of in the .
Export Skeleton nulls. Please note that the must be recorded for Skeleton bone tracking data to be exported. It exports 6 Degree of Freedom data for every bone segment in selected Skeletons.
Can only be exported when is recorded for exported Rigid Body assets. Exports 6 Degree of Freedom data for selected Rigid Bodies. Orientation axes are displayed on the geometrical center of each Rigid Body.
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 or in the .
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 of in the .
