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  • If the DTrack indicator is not green make sure that DTrack is running and that the Output settings in DTrack and the port number configured for the LPVR driver are correct and agree.

  • If the indicator for the platform IMU is red, make sure its USB cable is connected and restart Varjo Base. We discuss its setup in detail further down.

  • If the headset IMU indicator is red, please restart Varjo Base. If it remains red, please make sure Varjo Base doesn’t display any errors.

Adjustment of

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Platform IMU

Follow this tutorial to install and run Please follow our tutorial for initial installation of the vehicle-fixed LPMS-IG1 IMU (the “Platform IMU”). If you are using LPVR-DUO for Varjo with the ART SmartTrack and our provided IMU holder, you should be done at this step. If you are using another setup, please follow the steps a detailed calibration guide can be found in the fold-out below.

Expand
titleManual Calibration Procedure

  • In a first step the orientation of the internal coordinate system of the vehicle fixed IMU and the optical tracking system needs to be defined. For this purpose, attach an optical marker to the enclosure of the IMU and create a new rigid body in the optical tracking software.

  • To activate the calibration features of LPVR, click on Show Additional Features on the LPVR configuration page.

  • Activate the automatic pivot point calibration by selecting the optical tracking system (“DTrack” or “my_art”) in the absolute source field with rigid body id tracking idand the vehicle fixed IMU (“Platform IMU” or “reference_imu”) in the imu source field. Clicking Find Rotation will start the calibration process.

  • During the calibration process, slowly rotate the IMU with attached optical marker within the view of the optical tracking system. Pause the rotation from time-to-time to allow for some internal processing. After the calibration process is finished the result will be output below the calibration feature dialog. The output quaternion needs to be manually inserted into referenceToOpticalQuat.

  • Fix the platform IMU to the vehicle in the intended location with the optical marker still attached. Make sure that it is visible to DTrack. We now need to read the orientation quaternion from Varjo Bases log files and enter them as referenceOrientationQuat around line 59 of the configuration. Accessing the Varjo Base log files takes a few steps which we detail below.

  • Open Diagnostics from the Support menu in Varjo Base

  • On the next screen, click Start

  • Click “Skip” in order to not record eye tracking data

  • You are now presented with the following screen which provides you with a link to the location where the log files are stored. Click on “Show folder”

  • Enter the log folder, out of the files named tracking_<number>.log select the latest one and open it. Near its end search for lines similar to this
    20210120 15:16:31.156 --- [Varjo::Tracking::PluginUtilityAPI::WriteLogMessage] PLUGIN: [INFO] new pose: q = {"w":0.9913584114738726,"x":0.1302836073262127,"y":0.006246731684853627,"z":-0.013979051208529776} pos = {"x":-1.1893610000000001,"y":0.831757,"z":-0.936706}

  • Replace the contents of referenceOrientationQuat in the configuration web page with the values of q in the log file, i.e. {"w":0.9913584114738726,"x":0.1302836073262127,"y":0.006246731684853627,"z":-0.013979051208529776} in this example.

  • After the above procedure the optical marker can be detached from the platform IMU.

NOTE: The platform IMU should now not be moved anymore. The system should now be sufficiently calibrated for operation.

You should now be able to display content fixed to the vehicle coordinate system. E.g. when you drive a curve in a vehicle and keep looking straight ahead, objects in VR/AR should not change their position and orientation.

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