Cross Reality (CR) is a new emerging field based on the current developments in Mixed Reality hardware, especially supported by the broad market penetration of video-based see-through Head-Mounted Displays. It refers to applications that span across different stages (real, Augmented Reality, Augmented Virtuality, Virtual Reality) of the reality-virtuality continuum, where users are interconnected between different stages and/or are able to transition between these stages. This publication follows the concept of other grand challenges publications and reflects the discussion of various researchers invested in CR. After an initial discussion at the 1stJoint Workshop on Cross Reality at IEEE ISMAR 2023, six topic groups have been identified, leading to 22 challenges, which were discussed in groups over the period of multiple months. The discussion of these challenges should act as a road map for future research in the area of CR.

In shared virtual spaces, users tend to mimic real-world social behaviors, such as maintaining interpersonal distances and avoiding collisions. During remote collaboration, these behaviors can limit movement and positioning, despite users are not co-located. Prior work found that avatar transparency reduces users’ positioning constraints induced by social behaviors, as long as social presence between collaborators. Our goal was to develop a system that enhances navigation freedom without significantly increasing social presence. We designed a transparency management system based on interpersonal distances and collision avoidance. A user study involving groups of three remote collaborators indicated that our system reduced the distances between users compared to fully opaque avatars without any significant difference in social presence.

Collaborative Augmented Reality (CAR) offers disruptive ways for people to collaborate. However, this emerging technology must improve its acceptance, efficiency, and usability to scale up and, for example, support augmented operations executed by technicians. This paper presents our CAR system and its experimentation during a cooperative puzzle-solving task. Our system provides collaborators with a shared virtual space allowing verbal and non-verbal interpersonal communications, and intuitive interactions with shared virtual replicas of real objects. Our system also integrates avatars embodied by remote users. We conducted a dual-user study comparing colocated and remote solving of a puzzle virtual replica with its real solving. We evaluated task performance, collaboration, mutual awareness, spatial presence, and copresence, usability, and preference. We found that, if real is preferred and more efficient than our CAR system, CAR is reaching favorable usability levels. We also found that remote augmented reality including full-body avatars offers similar results to colocated augmented reality. This preliminary work paves the way for future research aiming to support and enhance the design and making of Collaborative Augmented Reality systems dedicated to augmented operations.