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Once the driver has finished installing start Varjo Base.
In Varjo Base go to the system tab and select LPVR-DUO-Varjo as headset tracking method from the dropdown menu.
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Point your web browser to http://localhost:7119. A configuration webpage (depicted below) should pop up.
In order to use LPVR-DUO we need to connect the various parts and we need to calibrate the orientation of the reference IMU that is mounted to the vehicle.
in order to receive data from DTrack the port number configured on line 7 needs to match the one configured in DTrack. The default configuration uses port number 5000 which is also the default for DTrack.
In DTrack’s Output Settings you need to enable one channel to send to “this computer” with at least “ts” and “6d” output enabled. Depending on your firewall settings you may have to select “act as router for tracking output”.
You also need to configure the correct body ID for the tracked body associated with the headset. This number goes on line 42 of the configuration
Lastly, for the purpose of calibration, we also need a tracking body attached to the reference IMU. Its tracking body ID goes on line 69.
Once these settings are complete, click the button labelled “Push To Driver” above the input field. The driver should now have adopted the settings.
If you have already calibrated the headset tracking body (see above), you should be able to now use the headset with DTrack tracking. It should also react to motion of the reference IMU. Though as long as the reference IMU is not calibrated, this motion should not make much sense.
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Calibration Procedure
Follow this tutorial to install and run the vehicle-fixed LPMS-IG1 IMU.
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.
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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 theimu sourcefield. 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.
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Fix the reference 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
referenceOrientationQuataround 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>.logselect 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
referenceOrientationQuatin the configuration web page with the values ofqin 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 reference IMU.
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