World-in-Miniatures (WIMs) are an established technique in virtual reality (VR) that provide an overview of the surrounding virtual environment. While traditionally used to support navigation over larger distances and distant manipulation in large-scale spaces, their potential for comparing alternative versions of a virtual environment has not been exploited. In this paper, we introduce a Multi-WIM paradigm that facilitates the detailed exploration and comparison of urban planning alternatives. Each alternative is visualized in a separate WIM. The WIMs can be arranged side by side (juxtaposed) or stacked. Stacking allows toggling between alternatives or using a swipe tool where on each side one alternative is shown. These three modes (juxtaposed, toggle, swipe) provide flexible ways of exploring differences and similarities between alternatives, with highlighting functionalities that reveal differences of functional units across designs. We evaluated the Multi-WIM paradigm in a single-factor VR user study (N=24), combining a single-user experiment with a multi-user exploration. Participants had to identify differences and estimate distances, areas and heights across urban planning alternatives. Results show that the stacked toggle mode was significantly faster for finding differences while the juxtaposed view better supported a landmark recall task. Furthermore, toggle was the overall preferred technique in the single-user mode. In contrast, in multi-user settings participants favored juxtaposed, as it fostered collaborative discussion and shared sensemaking. The identified design trade-offs between efficiency and collaboration indicate the need to incorporate all three WIM modes, together with seamless transitions among them, in urban planning applications so as to accommodate both loosely and tightly coupled phases of collaboration.

Making virtual reality (VR) more accessible for novice and nondigital users has largely focused on single-user solutions, such as tutorials, tooltips, and visual guidance cues. While structured onboarding protocols have proven effective, they do not scale well for multiple collocated users due to varying assistance needs, different learning speeds, and guidance preferences. Additionally, the sudden isolation upon entering VR can cause disorientation, particularly in group settings where users may lose awareness of their physical and social surrounding. This paper proposes a novel onboarding framework that extends traditional procedures with four phases: 1) entering video see-through mixed reality after putting on the HMD, 2) interactive tutorials in mixed reality, 3) adaptive group transition strategies into VR, and 4) structured exit mechanisms. In our implementation of the framework, we explore three concepts for group transitions: individual, sequential, and collective. In a user study with 36 participants, we collected feedback on our mixedreality onboarding approach and evaluate the usability, co-presence, agency, and continuity of our three proposed transition techniques and compare it to the common direct transition into virtual reality. Our results indicate a clear preference for onboarding through an additional mixed reality stage and provide valuable insights into advantages and trade-offs of the different group transition strategies.

In collocated social virtual reality, the relative physical and virtual positions of users are often synchronised to reduce audio-visual inconsistencies and the risk of collisions between users. For virtual navigation previous work has proposed group navigation techniques that maintain spatial synchronisation. This, however, limits user autonomy and can be particularly frustrating when some users would prefer to remain at their current virtual position, as can be the case when users have differing goals, interests, or tasks within the virtual environment. In this paper, we introduce a two-phase confirmation-based group navigation concept for collocated scenarios which allows users to stay behind and catch up to the group based on individual confirmation. The confirmation to catch up can be triggered by the group’s guide, the individual user or both. Ghost avatars, which visualise the physical locations of other users, are used to avoid physical collisions in situations where part of the group has already virtually navigated to a new location. We evaluate the three confirmation-based techniques in a user study (N = 24) in the context of a guided tour in a virtual museum and compare it to a baseline group navigation technique. Our findings show that users prefer having the autonomy to decide when to follow their group. Despite increased complexity, the proposed techniques achieved comparable levels of co-presence, spatial orientation, and understanding of others’ positions in both the virtual and physical environments as the baseline, effectively balancing user autonomy, navigation understanding and social experience.

Conversational agents in virtual environments are an established approach for immersively conveying the information and narratives of museums and cultural heritage while expanding their accessibility to a wider and remote audience. The rapid development of large language models and text-to-speech technologies has raised the agents’ conversational level significantly, which allows their use for proactive guidance of visitors. This raises the vital question of how such agents should be visually represented to promote Knowledge transfer in immersive virtual environments. In this paper, we compared two representation concepts for agent embodiments in the context of a virtual museum by examining a stylized humanoid guide and a novel animism-based approach that enables users to talk to exhibited objects. Our work addresses the challenge of naturally introducing a virtual educational environment to users and encouraging their interest and engagement with the content. A user study $(N=29)$ revealed high usability and similar presence scores for the experience with each of the embodiments. A majority of participants showed a preference for the animated objects. In terms of user experience, they evoked significant stimulation and high levels of engagement. Our results suggest that agents that show emotions through appropriate word choice influence engagement levels. Based on our findings, we recommend humanoid guides for delivering general background information, while animated objects promote detailed questions about their own stories and a more stimulating exchange.

Standing in a large crowd can be uncomfortable and usually results in other users obstructing the view of the virtual environment. In this paper, we present four techniques designed to improve the user’s view in crowded environments. Inspired by related work on various transparency and clipping techniques, as well as observed user behavior in crowded scenarios, our paper addresses the visibility problem by locally manipulating the appearance of other users. Three of our techniques define a region of interest using a handheld flashlight metaphor. Depending on the technique, occluding users are either pushed to the side, scaled, or made partially transparent. The fourth technique allows users to vertically adjust their position. A user study with 24 participants found that the transparency technique was advantageous for quick search tasks. However, in a realistic museum setting, no clear favorite could be determined because the techniques make different trade-offs and users weighted these aspects differently. In a final ranking, the vertical position adjustment and transparency techniques were the most popular, but the scaling technique and vertical position adjustment were found to be the most natural.

Embodied conversational agents are an established approach for immersively conveying the narratives and information of virtual museums. Recent advances in large language models and text-to-speech systems enable the active guidance of users by agents and raise the question of how such assistants should be visually embodied to engage visitors and promote knowledge transfer. This demo showcases a stylized humanoid guide, a novel animism-based approach with speaking objects, and a combination of both concepts to interactively guide users through a digital replica of the famous Gropius Room at the Bauhaus University in Weimar.

The combination of smartphone Augmented Reality (AR) and Virtual Reality (VR) makes it possible for on-site and remote users to simultaneously explore a physical space and its digital twin through an asymmetric Collaborative Virtual Environment (CVE). In this paper, we investigate two spatial awareness visualizations to enable joint exploration of a space for dyads consisting of a smartphone AR user and a head-mounted display VR user. Our study revealed that both, a mini-map-based method and an egocentric compass method with a path visualization, enabled the on-site visitors to locate and follow a virtual companion reliably and quickly. Furthermore, the embodiment of the AR user by an inverse kinematics avatar allowed the use of natural gestures such as pointing and waving which was preferred over text messages by the participants of our study. In an expert review in a museum and its digital twin we observed an overall high social presence for on-site AR and remote VR visitors and found that the visualizations and the avatar embodiment successfully facilitated their communication and collaboration.

Image-based 3D reconstructions and their visualization in virtual reality promise novel opportunities to explore and analyze 3D reconstructions of real objects, buildings and places. However, the faithfulness of the presented data is not always obvious and, in most cases, a 3D reconstruction cannot be compared directly to its corresponding real world instance. However, in case of reconstruction methods based on structure from motion (SFM), a large number of raw photos is available. This motivated us to develop a novel interaction technique for the visual comparison of details of 3D models with projections of the corresponding image sections, e.g. in order to rapidly verify the authenticity of perceived features. The results of a formal user study (n=18) demonstrate the general usability of such visual provenance information as well as benefits of the comparison in vicinity of the features in question over a separate image gallery. Further observations informed our iterative design process and led to the development of an improved interactive visualization. Our final implementation provides a spatial and content-related overview while retaining the efficiency of the original approach.