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The OptiTrack VR driver lets you stream tracking data of the head-mounted display (HMD) and the controllers from Motive into SteamVR.
The plugin ships in an installer package (MSI), and it will set up the driver along with a tool for configuring streaming settings. Using this, the tracking data from Motive can be used to override the tracking of the VR system in any applications that are compatible with SteamVR.
Supported Systems: At the time of writing, only Vive HMDs (Vive, Vive Pro) are supported.
In order to track the HMD, markers must be attached. You can either use the Vive Pro clip with active markers or manually attach the markers onto the HMD.
Vive Pro Clip is an HMD enclosure with a total of 8 embedded active markers for tracking. This clip is designed to fit onto Vive Pro HMDs only, and you can simply attach this clip for tracking the HMD. The clip can be mounted easily by pushing clip the HMD it until the latches click, and you detach it by gently lifting the three latches located at the top, left, and right side of the clip.
Once the clip has been mounted, you will need to import the provided rigid body definition into Motive for the calibrate pivot point, which will be explained in the later sections.
You can either use the passive retro-reflective type markers or the active LED markers to track the HMD. Passive markers are retroreflective markers that reflect infrared light emitted from the IR LEDs on the camera. On the other hand, the active markers are LED markers that emit the IR light which gets uniquely identified in Motive. Either type of marker can be used to track HMDs. Using active marker is recommended especially for applications that involve tracking of multiple HMDs in the scene.
After the markers have been placed on the HMD, a rigid body must be defined from the 3D markers in Motive. For HMD tracking, it is important that the rigid body has a calibrated pivot point.
First of all, both the system and Motive should already be calibrated and configured for tracking active markers at this point. If not, please read through the Active Marker Tracking page and set up the tracking volume.
Download template rigid body definition from the following page (Vive_Pro.motive): download link.
Import the downloaded MOTIVE file into Motive. You can either click Open under the File tab or drag-and-drop the file directly onto Motive. Once it's loaded, the template rigid body definition will be listed under the Assets pane as Vive Pro, and you should see the rigid body getting tracked over the HMD markers in Motive.
Next step is to modify the properties of the imported rigid body definition so that it tracks only active markers with matching IDs. To do so, you will need to check active IDs from your HMD clip and input them into the properties of Vive Pro rigid body.
The last step is to refine the template rigid body definition so that it matches exactly how the markers are placed on your Vive Pro clip. Please follow the below steps so that the positions of all 8 markers get calibrated precisely.
For using OptiTrack system for VR applications, it is important that the pivot point of HMD rigid body gets placed at the appropriate location, which is at the root of the nose in between the eyes. External Pivot Alignment tool utilizes both the OptiTrack mocap system and the HMD's own tracking system (Oculus Tracker / Vive Base Stations) for precisely calculating the location of the pivot point of an HMD. When using this feature, both systems must be tracking the HMD simultaneously.
HMD Compatibility Notes:
SteamVR Required: The VR driver streams tracking data through SteamVR. Please make sure SteamVR is installed on the computer.
Download and run the installer. Then follow the installation prompts to set up the driver.
Once the driver has been successfully installed, launch the configuration utility software (C:\Program Files\OptiTrack\OpenVR Driver\ConfigUtil). Using this tool, you can load and check existing configurations and make changes to the settings as needed. To import current settings, click Load and to save out the changes, click Save.
If the configuration software detects a running instance of SteamVR through OpenVR, it will indicated as Initialized at the very top as shown in the image. Please note that when the settings are modifies while SteamVR is running, the SteamVR must be restarted to apply the changes.
First, configure the connection settings so that the driver listens to the Motive server where the tracking data is streamed from. The server address must match the address where Motive is streaming the data to, and the local address must match the IP address of the computer on the network where the driver is installed.
In the HMD section, enable the HMD and input the rigid body ID of the HMD. The rigid body ID must match the streaming ID property of the HMD rigid body definition in Motive.
Save the configurations by clicking on Save. This will modify the set of configurations in the steamvr.settings file in the steam installation directory, and they will override the HMD tracking with the tracking data from Motive. If you already had an instance of OpenVR or SteamVR running, restart the application to apply the changes.
Launch SteamVR. If the driver is successfully set up, you should see a tracker icon added beneath the HMD icon and the HMD will now be using the motion capture system instead of the base stations. Here, please make sure all of the lighthouse base stations are powered off.
Important note: External pivot calibration feature is not supported for controllers in Motive 2.1. This will be supported in the next release. In 2.1, you will need to manually position and orient the rigid body pivot point.
When needed, the Vive controllers can be configured as well. To do so, open the configuration utility tool while SteamVR is running. At the top of the configuration tool, it should indicate OpenVR status as Initialized and the controllers must be showing up in SteamVR. Then, in the controller sections, enable the controllers, specify the override device using the drop-down menu, and input the corresponding streaming ID of the controller rigid bodies in Motive. Once everything has been configured, save the changes and restart SteamVR. When the override is configured properly, SteamVR will have additional tracker icon per each enabled controller.
Now that the driver is set up, the HMD tracking will be overridden by tracking data from the mocap camera system, and you can integrate HMDs into the game engine through their own VR integration.
First of all, make sure the streaming settings are configured in Motive for streaming out the data:
Please make sure the Unity project is configured for OpenVR development. In Unity, open player settings from Edit → Project Settings → Player and select the OpenVR under the Virtual Reality SDK lists. Once this is set up properly, it will play the scene on the HMD.
Unity-OpenVR documenation: https://docs.unity3d.com/Manual/VRDevices-OpenVR.html
Make sure Unreal Engine is configured for SteamVR development. Please refer to the Unreal Engine's documentation for more information on developing for SteamVR.
Unreal Engine-SteamVR: https://docs.unrealengine.com/en-us/Platforms/SteamVR
This driver is designed for streaming of HMD and controller tracking data only. For streaming tracking data of other rigid body objects, you will need to use the corresponding plugins (UnrealEngine or Unity). In other words, the HMD tracking data will be streamed through the SteamVR using the driver you've installed, and all other tracking data will be streamed through the plugin's client origin.
When using both the VR driver and the plugins (UE/Unity), it is important that the client origin object is located at the origin without any rotations. In other words, it must have the position set to (0,0,0) and the rotation set to (0,0,0).
When using the Unreal Engine plugin, you will need to additionally create a custom pawn for properly aligning the coordinate systems between SteamVR and OptiTrack UE plugin: