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  • Room calibration

  • Adding and adjusting targets

We will add to this section soon. In the meantime refer to this page for ART setups and this page for OptiTrack setups from the LPVR documentation.

FusionHub on OpenXR HMDs

General

To make the tracking functionality of FusionHub available to standalone augmented and virtual reality headsets, it can be integrated with Android-compatible OpenXR HMDs. This works via a customized version of the ALVR / ALXR open source projects. ALVR allows streaming image data wirelessly from a host computer and interfaces to 3D content engines through SteamVR. While the original ALVR client was built to work on Meta Quest HMDs, the OpenXR version of ALVR called ALXR works in principle on any OpenXR compatible headset.

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The overall system consists of several applications running at the same time. As the development of this application is still work-in-progress, starting and configuring this solution can be a bit cumbersome. We are working on making the process easier as we move along.

On the headset:

  • FusionHub server (sensor connections, sensor fusion)

  • ALVR client (receives image data from ALVR server, connects to FusionHub server, sends pose information to ALVR server)

On the host computer:

  • FusionHub GUI (connects to FusionHub server on HMD, configures FusionHub, authenticates system)

  • ALVR server (receives pose information from client, sends pose information to SteamVR, sends image data to ALVR client, receives image information from SteamVR)

  • Optical tracking software etc.

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See the illustration below for a block diagram of the overall system:

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System Components

Applications

The following applications need to be started on the head mounted display and the host computer. They should all the included in the installation package that you received from us. We will discuss the order of starting these applications and what their status output should be below.

On the headset:

Application

Purpose

Name

FusionHub server

  • Receives IMU data from ALVR client

  • Receives optical tracking data

  • Sends sensor fusion result to ALVR client

FusionHub-v1.2-Android.apk

ALVR client

  • Receives image data from ALVR server

  • Connects to FusionHub server

  • Sends pose information to ALVR server

alvr_client_oculus_quest.apk

On the host computer:

Application

Purpose

Name

FusionHub GUI

  • Connects to FusionHub server on HMD

  • Configures FusionHub

  • Authenticates system

lp-fusionhub-dashboard.exe

ALVR server

  • Receives pose information from client

  • Sends pose information to SteamVR

  • Sends image data to ALVR client

  • Receives image information from SteamVR

ALVR Launcher.exe

Authentification

FusionHub authentificates itself via the GUI client application. In order to run the client application make sure to insert the LPVR USB dongle into the host computer. After the GUI client is connected to FusionHub on the HMD, FusionHub will start streaming pose data to ALVR.

Running the Solution

Installation

Install the FusionHub APK and ALVR client APK on the headset using a side-loading tool like Sidequest. In case of a Meta Quest HMD this will require you to put the HMD into developer mode.

The FusionHub GUI client and ALVR server can be started on the host PC without further installation, they can be run right out of the deployment folder.

Start-up

FusionHub

  • Start FusionHub on the HMD. A window showing the FusionHub console output should open.

  • Start the FusionHub GUI client on the host computer

  • Connect the GUI client to FusionHub on the HMD. Make sure HMD and host are in the same subnet. Enter the the correct IP of the HMD in the client before pressing connect.

  • Adjust parameter blocks as needed. Refer to the description of FusionHub BASE for configuration options. Note the following input and output ports that are hard-coded in the ALVR FusionHub API layer. These are already correctly set in the default configuration file installed with the FusionHub APK, so usually there is no need to change them.

Endpoint

Direction

Purpose

tcp://*:8799

Output

Fused pose data

tcp://localhost:8898

Input

IMU data

  • If it’s not running yet make sure to start and configure your optical tracking system. Once optical data is streamed to FusionHub, the nOptical counter in the GUI should be increasing.

ALVR

  • Start the ALVR server on the host. While the ALVR server starts up, it will automatically run SteamVR.

  • Start the ALVR client on the HMD. The HMD should be shown in the list of ALVR clients in the ALVR server application. In some cases you need to click the Trust button in the application to start streaming.

  • Once streaming starts, you should see the SteamVR default envinronment through the headset. Check if the nIMU counter in the FusionHub GUI is increasing. If both nOptical and nIMU are increasing then the communication between ALVR, optical tracking and FusionHub is working.

  • You can now use and calibrate the system as described in the FusioHub BASE section.

Release Notes

Version 1.2

Release date: 2023/1/5

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