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Mount platform, put on HMD. Look straight ahead.
Rotate the platform around the yaw, pitch and roll axis.
While the user keeps their head steady, the 3D image displayed in the HMD should be stationary.
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To optimize peformance of in-car tracking switch the internal tracking of Meta Quest 3 to 3-DOF, ie. switch the native pose tracking to off. |
External object tracking
In addition to delivering high-quality mixed reality and precise wireless headset tracking, LPVR-AIR seamlessly integrates controllers tracked by the HMD’s inside-out system with objects tracked via optical targets in the outside-in tracking frame, all within a unified global frame. The video above shows this unique capability in action.
When combined with our LPVR-CAD software, LPVR-AIR enables the tracking of any number of rigid bodies within the outside-in tracking volume. This provides an intuitive solution for tracking objects such as vehicle doors, steering wheels, or other cockpit components. Outside-in optical markers are lightweight, cost-effective, and require no power supply. With camera-based outside-in tracking, all objects within the tracking volume remain continuously tracked, regardless of whether the user is looking at them. They can be positioned with millimeter accuracy and function reliably under any lighting conditions, from bright daylight to dark studio environments.
See documentation about how to set up LPVR-CAD here: LPVR-CAD for SteamVR System Setup
When setting up LPVR-CAD in connection with LPVR-AIR, adjusting the headset related settings in LPVR-CAD isn’t needed. Uncheck the HMD active checkbox in the LPVR-CAD settings.
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The integration with LPVR-CAD is still work in progress, handle with care. We will release an updated version of LPVR-CAD for this purpose soon. |
Network setup
Router
In order to establish high bandwidth communication between the host and HMD we recommend setting up a 5GHz or for optimum performance a 6GHz (WIFI 6e) WIFI router. In some environments changing the internal channel setup of the router might increase performance. Some experimentation might be needed to find the perfect setting for your system.
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In SteamVR check Advanced Frame Timing for performance problems:
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In case of a sufficient rendering performance the advanced frame timing window should look like the output below:
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performance problems:
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In case of a sufficient rendering performance the advanced frame timing window should look like the output below:
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Optmizing LPVR-AIR
Frame timing
In order to avoid synchronization issues with frame synchronization between the HMD’s displays and the optical tracking data, ideally set the sampling frequency of the optical tracking to a multiple of the display frequency of the HMD, eg. 90Hz display ferquency and 180Hz optical tracking frequency. The HMD display frequency can be adjusted in the settings menu in ALVR.
WIFI environment quality
LPVR-AIR transmits images from the server to the HMD through a regular WIFI connection. Usually a 5G 5GHz band is used, in the optimum case we switch to WIFI 6EWIFI 6E ie. a 6GHz band. In environments without much WIFI interference, i.e. other devices using the same WIFI bands, this works very well. Crowded WIFI environments limit the bandwidth of the used WIFI transmission. This can lead to unpredictable loss of image and tracking quality. Examples of crowded spaces are public locations such as exhibition. Beware!
The Meta Quest firmware doesn't allow using a wired ethernet connection to mitigate the issue to provide a quick fix to this problem in urgent situations. Again, a clean execution of this project is prevented by inflexibility of Meta's software. Unfortunately there are no alternative wireless HMDs on the market that allow the modifications we need for an optimum implementation.
In an ideal setup, with several HMDs being used, each HMD uses a separate WIFI 6e channel, with the selected channels as far apart as possible.devices using the same WIFI bands, this works very well. Crowded WIFI environments limit the bandwidth of the used WIFI transmission. This can lead to unpredictable loss of image and tracking quality. Examples of crowded spaces are public locations such as exhibition. Beware!
Optical tracking parsing latency
Due to limited WIFI bandwidth and computing power limitations on the HMD pose information streamed from the the optical tracking system is parsed on the HMD with a significant delay. So far we have not found a way to reduce this delay. As described in the sensor fusion section, we added input from native inside-out tracking to the fusion in order to compensate for this latencysome delay. This lantency is mostly compensated by pose prediction. This isn’t perfect, therefore try to optimize the performance of your optical tracking system as much as possible.
References
ALVR open source project: https://github.com/alvr-org/ALVR
FusionHub documentation: FusionHub Manual
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