Bernhard E. Riecke

Jann Philipp Freiwald, Susanne Schmidt, Bernhard E. Riecke et al.

Natural interaction between multiple users within a shared virtual environment (VE) relies on each other's awareness of the current position of the interaction partners. This, however, cannot be warranted when users employ noncontinuous locomotion techniques, such as teleportation, which may cause confusion among bystanders. In this paper, we pursue two approaches to create a pleasant experience for both the moving user and the bystanders observing that movement. First, we will introduce a Smart Avatar system that delivers continuous full-body human representations for noncontinuous locomotion in shared virtual reality (VR) spaces. Smart Avatars imitate their assigned user's real-world movements when close-by and autonomously navigate to their user when the distance between them exceeds a certain threshold, i.e., after the user teleports. As part of the Smart Avatar system, we implemented four avatar transition techniques and compared them to conventional avatar locomotion in a user study, revealing significant positive effects on the observer's spatial awareness, as well as pragmatic and hedonic quality scores. Second, we introduce the concept of Stuttered Locomotion, which can be applied to any continuous locomotion method. By converting a continuous movement into short-interval teleport steps, we provide the merits of non-continuous locomotion for the moving user while observers can easily keep track of their path. Thus, while the experience for observers is similarly positive as with continuous motion, a user study confirmed that Stuttered Locomotion can significantly reduce the occurrence of cybersickness symptoms for the moving user, making it an attractive choice for shared VEs. We will discuss the potential of Smart Avatars and Stuttered Locomotion for shared VR experiences, both when applied individually and in combination.

Botao Amber Hu, Yilan Elan Tao, Bernhard Riecke et al.

Mixed reality systems support shared anchors and co-located interaction, yet they lack a socially legible protocol for entering another person's mixed reality in public settings. We frame this as a protocol problem: co-located MR sharing requires a staged sequence -- Discover, Consent, Confirm, Allow, Spatial Colocation, Sync Objects, Permission Management -- each demanding user understanding and agreement. Using AirDrop and Apple Vision Pro SharePlay as a baseline, we show that MR encounter complexity far exceeds file transfer, yet must feel equally effortless. We present TouchPort, an embodied sharing protocol that collapses this multi-stage sequence into a single gesture: a handshake and pull that simultaneously signals intent, negotiates consent, and initiates a temporary shared encounter layer between otherwise separate mixed realities. Through three implied scenarios, we demonstrate the protocol's expressive range in the transition from isolated to spontaneously shared realities. We discuss how embodied gestures can address the consent problem in ubiquitous MR and examine the ethical tensions of encounter protocols for MR futures.