Redirected Walking for Multi-User eXtended Reality Experiences with Confined Physical Spaces

eXtended Reality (XR) applications allow the user to explore nearly infinite virtual worlds in a truly immersive way. However, wandering around through these Virtual Environments (VE)s while physically walking in reality is heavily constrained by the size of the Physical Environment (PE). Therefore, in the last years different techniques have been devised to improve Locomotion in XR. One of these is Redirected Walking (RDW), which aims to find a balance between immersion and PE requirements by steering users away from the boundaries of the PE while allowing for arbitrary motion in the VE. However, current RDW methods still require large PEs, as to avoid obstacles and other users. Moreover, they introduce unnatural alterations in the natural path of the user, which can trigger perception anomalies, such as cybersickness or break of presence. These circumstances limit their usage in real life scenarios. This paper introduces a novel RDW algorithm, with the focus on allowing multiple users to explore an infinite VE in a confined space (6x6 m<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>). To evaluate it, we designed a multi-user Virtual Reality (VR) maze game, and benchmarked it against the state-of-the-art. A subjective study (20 participants) was conducted, where objective metrics, e.g., the path and the speed of the user, were combined wit subjective perception analysis in terms of their cybersickness levels. Our results show that our method reduces the appearance of cybersickness appearance in 80% of participants compared to the state-of-the-art. These findings show the applicability of RDW to multi-user VR with constrained environments.