Extended Reality (XR) offers a fascinating capability to transport individuals through time and space. However, are there ways to keep the users grounded in reality while exploring distant landscapes or unfamiliar places? We propose in this paper a Point of Interest portal-based navigation technique that takes full advantage of the available, often limited, physical space of the user while still facilitating natural walking in a virtual environment. This technique can be beneficial for the exploration of Points of Interest (PoIs), which is a recurrent situation in virtual museum visits. It ensures consistency between the physical workspace while a user moves from one PoI to the next, enabling applicability beyond Virtual Reality (VR) and into Mixed Reality (MR) scenarios. The connection of different PoIs in the virtual space is achieved with portals, which are strategically placed in the physical workspace. In order to evaluate the efficiency of this technique, in terms of time, presence and user subjective preference, we conducted an experiment with 19 participants who visited artefacts in various rooms of a fictitious virtual museum. The results indicated that the PoI-based portal technique delivers performance comparable to the most well-known navigation technique (teleportation), while maintaining a balance between immersion in the virtual environment and awareness of the physical space, and offering better spatial consistency. Therefore, it can be considered a viable solution for cross-reality interaction.

Virtual Reality (VR) has repeatedly proven its effectiveness in student learning. However, despite its benefits, the student equipped with a personal headset remains isolated from the real world while immersed in a virtual space and the classic student-teacher model of learning is difficult to transpose in such a situation. This study aims to bring the teacher back into the learning process when students use a VR headset. We describe the benefits of using a companion for educational purposes, taking as a test case the concept of gravity. We present an experimental setup designed to compare three different teaching contexts: with a physically present real teacher, using a live video of the teacher, and with a VR avatar of the teacher. We designed and evaluated three scenarios to teach the concept of gravity: an introduction to the concept of free fall, a parabolic trajectory workshop and a final exercise combining both approaches. Due to sanitary conditions, only pre-tests are reported. The results showed that the effectiveness of using the VR simulations for learning and the self-confidence level of the students increased as well. The interviews show that the students ranked the teaching modes in this order: VR companion mode, video communication and real teacher.

In the present study we conducted a systematic review on user studies for Archaeology in eXtended Reality of the last 10 years. After a screening and selection process, 52 articles were selected for an in-depth analysis. Their classification follows different axes: devices, location dependency, type of users, interaction and collaboration. We also organised the existing user studies according to tasks, evaluation measurements, number of participants, and how the study was conducted (pre-test and/or post-test, formative and summative evaluation, quantitative and qualitative data). We found an intertwined relation between Archaeology and Cultural Heritage, which is reflected in the vast presence of applications for museum exhibitions and tours on archaeological sites. Similarities between systems developed for archaeologists and for general public were also investigated. Our purpose was to find a common ground between different user studies that could help designers of the next systems have a base on which they can build their system. We also highlighted which would be the preferred and most suitable evaluation techniques, when they are needed, with the type of users to address. The results show a heterogeneity of measurable variables and possible choices, but some guidelines could be derived.

In many collaborative virtual reality applications, co-located users often have their relative position in the virtual environment matching the one in the real world. The resulting spatial consistency facilitates the co-manipulation of shared tangible props and enables the users to have direct physical contact with each other. However, these applications usually exclude their individual virtual navigation capability, such as teleportation, as it may break the spatial configuration between the real and virtual world. As a result, the users can only explore the virtual environment of approximately similar size and shape compared to their physical workspace. Moreover, their individual tasks with unlimited virtual navigation capability, which often take part in a continuous workflow of a complex collaborative scenario, have to be removed due to this constraint. This work aims to help overcome these limits by allowing users to recover spatial consistency after individual teleportation in order to re-establish their position in the current context of the collaborative task. We use a virtual representation of the user’s shared physical workspace and develop two different techniques to position it in the virtual environment. The first technique allows one user to fully position the virtual workspace, and the second approach enables concurrent positioning by equally integrating the input from all the users. We compared these two techniques in a controlled experiment in a virtual assembly task. The results show that allowing two users to manipulate the workspace significantly reduced the time they spent negotiating the position of the future workspace. However, the inevitable conflicts in simultaneous co-manipulation were also a little confusing to them.

We propose a novel technique to facilitate the selection of data points, a type of data representation we often work with in immersive analytics. We designed and implemented this technique based on the expansion of data points following Fitt’s law. A user study was conducted in an headset-based augmented reality environment. The results significantly highlight the performance of our technique in helping the user select data points and their subjective appreciation in working with the expendable data points.

Industrial design review is an iterative process which mainly relies on two steps involving many stakeholders: design discussion and CAD data adjustment. We investigate how a wall-sized display could be used to merge these two steps by allowing multidisciplinary collaborators to simultaneously generate and explore design alternatives. We designed ShapeCompare based on the feedback from a usability study. It enables multiple users to compute and distribute CAD data with touch interaction. To assess the benefit of the wall-sized display in such context, we ran a controlled experiment which aims to compare ShapeCompare with a visualization technique suitable for standard screens. The results show that pairs of participants performed a constraint solving task faster and used more deictic instructions with ShapeCompare. From these findings, we draw generic recommendations for collaborative exploration of alternatives.

Teleportation is a navigation technique widely used in virtual reality applications using head-mounted displays. Basic teleportation usually moves a user’s viewpoint to a new destination of the virtual environment without taking into account the physical space surrounding them. However, considering the user’s real workspace is crucial for preventing them from reaching its limits and thus managing direct access to multiple virtual objects. In this paper, we propose to display a virtual representation of the user’s real workspace before the teleportation, and compare manual and automatic techniques for positioning such a virtual workspace. For manual positioning, the user adjusts the position and orientation of their future virtual workspace. A first controlled experiment compared exocentric and egocentric manipulation techniques with different virtual workspace representations, including or not an avatar at the user’s future destination. Although exocentric and egocentric techniques result in a similar level of performance, representations with an avatar help the user to understand better how they will land after teleportation. For automatic positioning, the user selects their future virtual workspace among relevant options generated at runtime. A second controlled experiment shows that the manual technique selected from the first experiment and the automatic technique are more efficient than the basic teleportation. Besides, the manual technique seems to be more suitable for crowded scenes than the automatic one.

Spatial presence encompasses the user's ability to experience a sense of "being there". While particular attention was given to assess spatial presence in real and virtual environments, few have been interested in measuring it in telepresence situations. To bridge this gap, the present work introduces a study that compares the execution of a task in three conditions: a real physical environment, a remote environment via a telepresence system, and a virtual simulation of the real environment. Following a within-subject design, 27 participants performed a navigation task consisting in following a route while avoiding obstacles. Spatial presence and five related factors (affordance, enjoyment, attention allocation, reality, and cybersickness) were evaluated using a presence questionnaire. In addition, performance measures were gathered regarding environment recollection and task execution. The evaluation also included a behavioral metric measured by obstacle avoidance distance extracted from participants' trajectories. Results indicated a higher presence in the real environment, along with the best performance measures. No difference was found in spatial presence between the remote and the virtual conditions, although a higher degree of affordance and enjoyment was attributed to the virtual environment, and a higher degree of reality was attributed to the remote environment. The number of collisions was found to be lower in the remote condition compared to the virtual condition. Similarly, the avoidance distance was also bigger (and almost similar) in the real and the remote environments compared to the virtual environment indicating a greater caution of participants. These cues highlight that the behavior of participants in the remote condition was closer to their behavior in the real situation than it was in the virtual condition. Furthermore, positive correlations were found between the reality factor and two of the three performance measures, as well as with the behavioral metric. This suggests that the degree of physical existence of the space in which participants operate can influence their performance and behavior.

A method that allows quick estimation of Redirection Detection Thresholds (RDTs) is not only useful for identifying factors that contribute to the detection of redirections, but can also provide timely inputs for personalized redirected walking control. In aim to achieve quick RDT estimation, we opted for a classical psychophysical method - the Method of Adjustment (MoA), and compared it against commonly used method for RDT estimation (i.e. MCS-2AFC) to see their difference. Preliminary results show that MoA allows to save about 33% experiment time when compared with MCS-2AFC while getting overall similar RDT estimations on the same population.

This paper presents an experiment assessing the feeling of spatial presence in both real and remote environments (respectively the socalled “natural presence” and “telepresence”). Twenty-eight (28) participants performed a 3D-pointing task while being located in a real office and the same office remotely rendered over HMD. The spatial presence was evaluated by means of the ITC-SOPI questionnaire and users' behaviour analysis (trajectories of head during the task). The analysis also included the effect of different levels of immersion of the system - visual-only versus visual and audio - rendering in such environments. The results show a higher sense of spatial presence for the remote condition, regardless of the degree of immersion, and for the “visual and audio” condition regardless of the environment. Additionally, trajectory analysis of users' heads reveals that participants behaved similarly in both environments.

In a Multi-stereoscopic immersive system, several users sharing the same restricted workspace, e.g. a CAVE, may need to perform independent navigation to achieve loosely coupled collaboration tasks for a complex scenario. In this context, a proper navigation paradigm should provide users both an efficient control of virtual navigation and a guarantee of users' safety in the real workspace relative to the display system and between users. In this aim, we propose several alterations of the human joystick metaphor by introducing implicit adaptive control to allow safe individual navigation for multiple users. We conducted a user study with an object-finding task in a double-stereoscopic CAVE-like system to evaluate both users' navigation performance in the virtual world and their behavior in the real workspace under different conditions. The results highlight that the improved paradigm allows two users to navigate independently despite physical system limitations.

BlenderVR is an open-source project framework for interactive and immersive applications based on an extension of the Blender Game Engine to Virtual Reality applications. BlenderVR is a generalization of the BlenderCAVE project, accounting for alternate platforms (e.g., HMD, video-walls). The goal is to provide a flexible and easy to use framework for the creation of VR applications for various platforms, making use of the existing power of the BGE's graphics rendering and physics engine. Compatible with 3 major Operating Systems, BlenderVR has been developed by VR researchers with support from the Blender Community. BlenderVR currently handles multi-screen/multi-user tracked stereoscopic rendering through efficient low-level master/slave synchronization process with multimodal interactions via OSC and VRPN protocols.

6DoF navigation in a virtual world can usually be implemented by two types of navigation techniques: joystick-based input devices and steering metaphors based on movements of the user's body, e.g. head-controlled paradigms. These two different types of 6DoF navigation techniques provide users with the same level of control, but the latter introduces the user's physical movements in the navigation, which we believe will improve the navigation experience in immersive virtual environments. In this paper, we compare these two types of 6DoF navigation techniques in an immersive context, through an experiment using both objective and subjective measurements to assess user performance, the occurrence of cybersickness symptoms and the level of presence, when using either of these navigation paradigms.

Virtual Reality (VR) systems cannot be promoted for complex applications (involving the interpretation of massive and intricate databases) without creating natural and ”transparent” user interfaces: intuitive interfaces are required to bring non-expert users to use VR technologies. Many studies have been carried out on multimodal and collaborative systems in VR. Although these two aspects are usually studied separately, they share interesting similarities. Our work focuses on the way to manage multimodal and collaborative interactions in a same process. We present here the similarities between these two processes and the main features of a reconfigurable multimodal and collaborative supervisor for Virtual Environments (VEs). The aim of such a system is to ensure the merge of pieces of information coming from VR devices (tracking, gestures, speech, haptics, etc.), to control immersive multi-user applications using the main communication and sensorimotor channels of humans. The framework's architecture of this supervisor wants to be generic, modular and reconfigurable (via an XML configuration file), in order to be applied to many different contexts.

Our goal is to investigate new interaction techniques, using the haptic modality for CAD applications. An important issue in CAD systems is the modification of the Boundary Representation (B-Rep) of 3D objects. However, this fundamental task is only possible if a geometric element (vertex, edge, face) has already been selected. This paper focuses on several haptic selection methods to solve specific geometric constraints (differentiation of topological entities, variable density of the geometry, concavities) during the edition of a CAD model. Evaluation studies are carried out to compare the impact of these haptic methods on user performance. The results of these experiments are used to create a global haptic selection method for CAD editing.

In this paper we investigate attraction techniques, using the haptic modality, for CAD applications. An important issue in CAD systems is the modification of the Boundary Representation (B-Rep) of 3D objects. However, this fundamental task is possible only if a geometric element (vertex, edge, face) has already been selected. This paper focuses on a generic force feedback model of haptic attraction for CAD applications. Our model is flexible and allows the experimentation of several behaviours. Several evaluation studies are carried out to compare the impact of the model parameters on the user performance and comfort of use.

In this paper we present a comparative evaluation of haptic renderings for CFD data studied in virtual reality environments. We implemented haptics on both explicit (polygonal) and volumetric representations of isosurfaces. The haptic methods implemented go from attractive renderings, to volumic transfer functions as well as rigid contact methods. We lead several experiments to find the optimal haptic representations for CFD data analysis.

Summary form only given. The emergence of new medical image detectors such as multi-array scanners and the large diffusion of PET-scans has conditioned the modern medical practise. Indeed, the exams are more volumetric and more precise. We develop new medical software that allows us to classify exams. Coupled with a region of interest localization, it improves significantly the diagnosis time. The originality of our method resides in the application of the belief theory to medical image classification. The interest of belief theory lies in giving a formal representation of the inaccurate and uncertain aspect of information. Moreover, the concept of "extended open world" is well suited since it reduces the misclassification by introducing a class called "unknown". Indeed, we consider that it's better to consider an exam or an organ as unknown than misclassifying it. Two applications were performed: first, the exam type was identified among three major classes (abdomino-pelvic, cranial, and pulmonary). The others are gathered in the fourth special class "unknown". Second, according to a user request, the slices containing the specified organ are automatically selected.

Many applications using Virtual Reality (VR) require free hand navigation control. This forbids the use of devices such as Joystick, 3D mouse, ... That is generally because hand-based gesture interaction must be dedicated to specific tasks: sculpting or grasping the objects, which compose a virtual scene. With this aim, we present a polyvalent display approach, which allows the system to determine the desired focus and the moving intention of the user for virtual navigations. After we point out the limits of the classical solutions used to control virtual navigations, we describe the conceptual and mathematical implementation of our approach. Some of our considerations depend on physiological and ergonomic constraints. We conclude on the first applications of our fully head tracking navigation controller.