MVN allows for object tracking with HTC Vive. Vive Hardware can be mounted on all sorts of objects to track orientation and position. With this, it is possible to move multiple objects freely around the Vive play area and use the data to move virtual objects.
This article helps you to get set up for a recording with HTC Vive Object Tracking.
Before you start, make sure that have:
- Correctly set up your Xsens Motion Capture (Link or Awinda) system
- Correctly set up the HTC Vive: HTC Vive Setup Guide
NOTE: It is advised to use Vive Object tracking in combination with Vive Position Aiding (see Position Aiding: HTC Vive) for the best results. By default, SteamVR (Vive) and MVN systems have their own Coordinate system. With Vive Position Aiding the avatar is adapted to the SteamVR coordinate system.
1. Set up MVN Session
1. Open MVN
2. Start a new Session by clicking the Blank Page icon (or go to File > Start Motion Capture)
NOTE: If you are using an older version than MVN 2020.2, it is required to set up at least one Awinda or Link system.
4. In the Motion Capture Configuration window go to the Objects tab on the left side.
4. Enable Object with the Objects toggle switch.
NOTE: Available Vive TrackerID's will be shown in a List. To check TrackerID corresponds to which device, see the HTC Vive Setup Guide, Hardware chapter.
5. All hardware detected by SteamVR will be displayed.
6. Select the Hardware to use for object tracking.
7. Hardware can be Renamed by left-clicking twice on the Name
8. Smoothing can be enabled in the Filtering column.
NOTE: Vive Hardware may already be assigned an MVN System (for Position Aiding). In that case, MVN will indicate which system is using that Vive Hardware. It is possible to use Vive Hardware for Object Tracking and Position Aiding at the same time.
9. Press Ok in the bottom right of the Motion Capture Configuration Window
10. You should see the Vive Hardware and a XY-position graph in the viewport.
The Objects are represented by a Vive hardware model with the name of the Object above it. The orientation and position of this Vive hardware will be displayed and updated live in the Viewport.
|Top View||Side View|
In the Navigator, an Objects item is available which contains a data tab for all available Vive Hardware with the names as chosen in Objects setup. Each Object has Orientation and Position data.
2. Reset Floor
Depending on the SteamVR setup, In some cases, the hardware may appear above or below the MVN ground plane.
1. Place 1 Vive Tracker / Controller / Headset on the Floor.
2. Go to Tasks > Reset Floor (Shortkey: Ctrl + F)
3. This will reset the floor height to the lowest available Vive Hardware in MVN. This floor reset is only required to do once since the new floor height will be used for all Vive hardware (even ones that are connected after the reset).
NOTE: If your MVN is an older version than 2020.2, and you do not have an HMD, you have to reset the floor manually by changing the chaperon file: HTC Vive Adjust Floor Height Without HMD
3. Start Recording
Make sure the Vive Hardware is inside the play area.
1. To start a recording, press the record button
NOTE: If you are using Vive Object Tracking in combination with an MVN System, you first have to perform an MVN Calibration before recording.
2. After the take, press the Stop Recording button to stop the recording
After recording, MVN will create the following file type(s):
- .mvno file: contains the positional and rotational data from the Objects. This data can be exported to .fbx format: Exporting data from MVN
- .mvn file: contains the Motion Capture data (only created if a MVN system was enabled during the session)
- .mvns file: contains the Objects Data and Mocap Data combined in a session (only created if a MVN system was enabled during the session).
More info on file types can be found in MVN File Types
Files containing Object data can be exported to:
- FBX: Contains single points with position and rotation data for each Object.
- mp4: Video of the viewer
More info on exporting can be found in Exporting Data from MVN
Object data can also be streamed. This has to be enabled in the Network Streamer: Go Options > Network Streamer
For setting up a network stream to a specific 3rd party software check: Network Streamer in MVN
6. Position Aiding
If you want to interact with the Objects, it is advised to use Vive Object tracking in combination with Vive Position Aiding (see Position Aiding: HTC Vive) for the best results. By default, SteamVR (Vive) and MVN systems have their own Coordinate system. With Vive Position Aiding the avatar is adapted to the SteamVR coordinate system.
1. To play back the recorded session, open the .mvns file that was created. This will include the Mocap data and the Objects data.
Below, the difference between using no Position Aiding (left) and using Position Aiding (right) is illustrated.