# AprilTags in Unity: A Local Alternative to Shared Spatial Anchors for Synergistic Shared Space Applications Involving Extended Reality and the Internet of Things

## TL;DR

This paper introduces a local, privacy-preserving method for setting up shared extended reality (XR) spaces using AprilTags, eliminating the need for internet connectivity and cloud-based calibration.

## Contribution

A low-cost, local calibration system for XR using AprilTags is developed, avoiding privacy risks and internet dependency.

## Key findings

- The local AprilTags-based system successfully distributes location data among XR clients without internet connectivity.
- The method provides accurate and synchronized shared XR experiences for multiple users.
- The system is a privacy-preserving alternative to cloud-based spatial anchors.

## Abstract

The highlights of this work are listed below.

What are the main findings?
The serious privacy issue of the user being forced by extended reality (XR) headset manufacturing companies to have to upload the user’s setup and surroundings for traditional, legacy calibration can be addressed locally without compromising on the user’s privacy.By using Unity, Mirror Networking, and the QuestDisplayAccessDemo, a shared host system implemented locally can distribute location data with XR clients. Some performance analysis of the developed system is also included in this article.

The serious privacy issue of the user being forced by extended reality (XR) headset manufacturing companies to have to upload the user’s setup and surroundings for traditional, legacy calibration can be addressed locally without compromising on the user’s privacy.

By using Unity, Mirror Networking, and the QuestDisplayAccessDemo, a shared host system implemented locally can distribute location data with XR clients. Some performance analysis of the developed system is also included in this article.

What is the implication of the main finding?
This is a no-to-low-cost solution for XR headset calibration and localization that circumvents legacy calibration systems for XR headsets that essentially need high bandwidth.The solution is completely local and does not need internet connectivity, unlike the critical and traditional initial setup that can be implemented only in places that have high-bandwidth internet connectivity. This means that expensive XR headsets can now be used in any user environment without needing internet connection for setting them up.

This is a no-to-low-cost solution for XR headset calibration and localization that circumvents legacy calibration systems for XR headsets that essentially need high bandwidth.

The solution is completely local and does not need internet connectivity, unlike the critical and traditional initial setup that can be implemented only in places that have high-bandwidth internet connectivity. This means that expensive XR headsets can now be used in any user environment without needing internet connection for setting them up.

Creating shared spaces is a key part of making extended reality (XR) and Internet of Things (IoT) technology more interactive and collaborative. Currently, one system which stands out in achieving this end commercially involves spatial anchors. Due to the cloud-based nature of these anchors, they can introduce connectivity and privacy issues for projects which need to be isolated from the internet. This research attempts to explore and create a different approach that does not require internet connectivity. This work involves the creation of an AprilTags-based calibration system as a local solution for creating shared XR spaces and investigates its performance. AprilTags are simple, scannable markers that, through computer vision algorithms, can help XR devices figure out position and rotation in a three-dimensional space. This implies that multiple users can be in the same virtual space and in the real-world space at the same time, easily. Our tests in XR showed that this method is accurate and works well for synchronizing multiple users. This approach could make shared XR experiences faster, more private, and easier to use without depending on cloud-based calibration systems.