Search

One of the most essential interactions in Virtual Reality (VR) is the user’s ability to move around and explore the virtual environment. The design of the navigation technique plays a crucial role in the user experience since it determines key usability aspects. VR devices allow for an immersive exploration of 3D worlds, but navigation in VR is challenging for many users, due to potential usability issues related to specific VR controllers, user skills, and motion sickness. Although hundreds of interaction techniques have been proposed for this task, VR navigation still poses a high entry barrier for many users. In this paper we argue that adapting the navigation technique to its context of use can lead to substantial improvements in navigation usability and accessibility. The context of use includes the type of scene, the available physical space, as well as the profile of the user. We present a test platform to facilitate the design and fine-tuning of interaction techniques for 3D navigation. We focus on mainstream VR devices (headsets and controllers) and support the most common navigation metaphors (walking, flying, teleportation). The key idea is to let developers specify, at runtime, the exact mapping between user actions and locomotion changes, for any of the supported metaphors. Such mappings are described by a collection of parameters (e.g. maximum speed) whose values can be adjusted interactively through a GUI, or be provided by user-defined code which can be edited at runtime. Feedback obtained from developers suggests that this approach can be used to quickly adapt the navigation techniques to various people including persons with no previous 3D navigation skills, elderly people, and people with disabilities, as well as to the type, size and semantics of the virtual environment. This work has been funded by MCIN/AEI/10.13039/501100011033/FEDER ‘‘A way to make Europe’’. Pedret model partially funded by EU Horizon 2020, JPICH Conservation, Protection and Use initiative (JPICH-0127) and the Spanish Agencia Estatal de Investigación, grant PCI2020-111979 Enhancement of Heritage Experiences: the Middle Ages; Digital Layered Models of Architecture and Mural Paintings over Time (EHEM)

[EN] This research develops a novel teleoperation for robot manipulators based on augmented reality. The proposed interface is equipped with full capabilities in order to replace the classical teach pendant of the robot for carrying out teleoperation tasks. The proposed interface is based on an augmented reality headset for projecting computer-generated graphics onto the real environment and a gamepad to interact with the computer-generated graphics and provide robot commands. In order to demonstrate the benefits of the proposed method, several usability tests were conducted using a 6R industrial robot manipulator in order to compare the proposed interface and the conventional teach pendant interface for teleoperation tasks. In particular,the results ofthese usabilitytests show thattheproposedapproach is more intuitive, ergonomic,and easy to use. Furthermore, the comparison results also show that the proposed method clearly improves the velocity of the teleoperation task, regardless of the user's previous experience in robotics and augmented reality technology., This work was supported by the Spanish Government under the project DPI2017-87656-C2-1-R.

We created a virtual reality version of a 1983 performance by Dire Straits, this being a highly complex scenario consisting of both the virtual band performance and the appearance and behaviour of the virtual audience surrounding the participants. Our goal was to understand the responses of participants, and to learn how this type of scenario might be improved for later reconstructions of other concerts. To understand the responses of participants we carried out two studies which used sentiment analysis of texts written by the participants. Study 1 (n = 25) (Beacco et al. in IEEE Virtual Reality: 538–545, 2021) had the unexpected finding that negative sentiment was caused by the virtual audience, where e.g. some participants were fearful of being harassed by audience members. In Study 2 (n = 26) notwithstanding some changes, the audience again led to negative sentiment—e.g. a feeling of being stared at. For Study 2 we compared sentiment with questionnaire scores, finding that the illusion of being at the concert was associated with positive sentiment for males but negative for females. Overall, we found sentiment was dominated by responses to the audience rather than the band. Participants had been placed in an unusual situation, being alone at a concert, surrounded by strangers, who seemed to pose a social threat for some of them. We relate our findings to the concept of Plausibility, the illusion that events and situations in the VR are really happening. The results indicate high Plausibility, since the negative sentiment, for example in response to being started at, only makes sense if the events are experienced as actually happening. We conclude with the need for co-design of VR scenarios, and the use of sentiment analysis in this process, rather than sole reliance on concepts proposed by researchers, typically expressed through questionnaires, which may not reflect the experiences of participants.

Acceleration techniques for Rendering in general, and Ray-Casting in particular, have been the subject of much research in Computer Graphics. Most efforts have been focused on new data structures for efficient ray/scene traversal and intersection. In this paper, we propose an acceleration technique that approximates rendering and that is built around a new feature-based clustering approach. The technique starts preprocessing the scene by grouping elements according to their features using a set of channels based on an information theory-based approach. Then, at run-time, a rendering strategy uses that clustering information to reconstruct the final image, by deciding which areas could take advantage of the coherence in the features and thus, could be interpolated; and which areas require more involved calculations. This process starts with a low-resolution render that is iteratively refined up to the desired resolution by reusing previously computed pixels. Our experimental results show a significant speedup of an order of magnitude, depending on the complexity of the per-pixel calculations, the screen size of the objects, and the number of clusters. Rendering quality and speed directly depend on the number of clusters and the number of steps performed during the reconstruction procedure, and both can easily be set by the user. Our findings show that feature-based clustering can significantly impact rendering speed if samples are chosen to enable interpolation of smooth regions. Our technique, thus, accelerates a range of popular and costly techniques, ranging from texture mapping up to complex ambient occlusion, soft and hard shadow calculations, and it can even be used in conjunction with more traditional acceleration methods his work was partially funded by the TIN2017-88515-C2-2-R grant from Ministerio de Ciencia, Innovación y Universidades, Spain Open Access funding provided thanks to the CRUE-CSIC agreement with Elsevier

Authoring realistic behaviors to populate a large virtual city can be a cumbersome, time-consuming and error-prone task. Believable crowds require the effort of storytellers and programming experts working together for long periods of time. In this work, we present a new framework to allow users to generate populated environments in an easier and faster way, by relying on the use of procedural techniques. Our framework consists of the procedural generation of semantically-augmented virtual cities to drive the procedural generation and simulation of crowds. The main novelty lies in the generation of agendas for each individual inhabitant (alone or as part of a family) by using a rule-based grammar that combines city semantics with the autonomous persons' characteristics. Real-world data can be used to accommodate the generation of a virtual population, thus enabling the recreation of more realistic scenarios. Users can author a new population or city by editing rule files with the flexibility of re-using, combining or extending the rules of previous populations. The results show how logical and consistent behaviors can be easily generated for a large crowd providing a good starting point to bring virtual cities to life., Comment: Submitted

Archaeological excavations provide us with important clues about the past. Excavated artefacts represent an important connection to civilisations that no longer exist and help us understand some of their customs, traditions and common practices. With the help of academics and practitioners from various disciplines, the results of archaeological excavations can be analysed and a body of knowledge about the corresponding society can be created and shared with members of the general public. Museums have traditionally served the purpose of communicating this knowledge and backing it up with the help of the excavated artefacts. Many museum visitors, however, find it difficult to develop a coherent understanding of the corresponding society only based on the artefacts and annotations shown in museums. Effective modern techniques that have high potential in helping museum visitors with better understanding of the past are 3D reconstruction and virtual reality. 3D reconstruction offers a cost-effective way of recreating historical settlements in a computer-generated virtual environment, while virtual reality helps with immersing people into such environments and reaching a high degree of realism. With the help of these technologies, it becomes possible to relive history, imagine yourself being a part of the reconstructed society and learn about its culture firsthand. The combination of 3D reconstruction and virtual reality represents a very powerful learning tool; however, this tool has been rarely used in a museum setting and its correct use has not been properly investigated. In this paper, we present a study into using virtual reality in itinerant archaeological exhibitions. We discuss the lessons we have learned from developing an interactive virtual reality simulation of the Neolithic settlement of La Draga. These lessons feature our analysis of qualitative and quantitative feedback of museum visitors, as well as what we have learned from analysing their navigation and interaction patterns.

Virtual reality applications depend on multiple factors, for example, quality of rendering, responsiveness, and interfaces. In order to evaluate the relative contributions of different factors to quality of experience, post-exposure questionnaires are typically used. Questionnaires are problematic as the questions can frame how participants think about their experience and cannot easily take account of non-additivity among the various factors. Traditional experimental design can incorporate non-additivity but with a large factorial design table beyond two factors. Here, we extend a previous method by introducing a reinforcement learning (RL) agent that proposes possible changes to factor levels during the exposure and requires the participant to either accept these or not. Eventually, the RL converges on a policy where no further proposed changes are accepted. An experiment was carried out with 20 participants where four binary factors were considered. A consistent configuration of factors emerged where participants preferred to use a teleportation technique for navigation (compared to walking-in-place), a full-body representation (rather than hands only), the responsiveness of virtual human characters (compared to being ignored) and realistic compared to cartoon rendering. We propose this new method to evaluate participant choices and discuss various extensions. This research is supported by the European Research Council Advanced grant Moments in Time in Immersive Virtual Environments (MoTIVE) grant no. 742989 and all authors were funded by this grant except for G.S. who is supported by ‘la Caixa’ Foundation (ID 100010434) with Fellowship code no. LCF/BQ/DR19/11740007.

Path finding for autonomous agents has been traditionally driven by finding optimal paths, typically by using A* search or any of its variants. When it comes to simulating virtual humanoids, traditional approaches rarely consider aspects of human memory or orientation. In this work, we propose a new path finding algorithm, inspired by current research regarding how the brain learns and builds cognitive maps. Our method represents the space as a hexagonal grid with counters, based on brain research that has investigated how memory cells are fired. Our path finder then combines a method for exploring unknown environments while building such a cognitive map, with an A* search using a modified heuristic that takes into account the cognitive map. The resulting paths show how as the agent learns the environment, the paths become shorter and more consistent with the optimal A* search. Moreover, we run a perceptual study to demonstrate that the viewers could successfully identify the intended level of knowledge of the simulated agents. This line of research could enhance the believability of autonomous agents’ path finding in video games and other VR applications. This work was partly funded by the Spanish Ministry of Economy, Industry and Competitiveness under Grant No. TIN2017- 88515-C2-1-R.

Simulating virtual crowds is an important challenge in many areas such as games and virtual reality applications. A lot of effort has been dedicated to improving pathfinding, collision avoidance, or decision making, to achieve more realistic human-like behavior. However, crowd simulation will be far from appearing realistic as long as virtual humans are limited to walking animations. Including animation variety could greatly enhance the plausibility of the populated environment. In this paper, we evaluated to what extend animation variety can affect the perceived level of realism of a crowd, regardless of the appearance of the virtual agents (bots vs. humanoids). The goal of this study is to provide recommendations for crowd animation and rendering when simulating crowds. Our results show that the perceived realism of the crowd trajectories and animations is significantly higher when using a variety of animations as opposed to simply having locomotion animations, but only if we render realistic humanoids. If we can only render agents as bots, then there is no much gain from having animation variety, in fact, it could potentially lower the perceived quality of the trajectories.

We present methods used to produce and study a first version of an attempt to reconstruct a 1983 live rock concert in virtual reality. An approximately 10 minute performance by the rock band Dire Straits was rendered in virtual reality, based on the use of computer vision techniques to extract the appearance and movements of the band, and crowd simulation for the audience. An online pilot study was conducted where participants experienced the scenario and freely wrote about their experience. The documents produced were analyzed using sentiment analysis, and groups of responses with similar sentiment scores were found and compared. The results showed that some participants were disturbed not by the band performance but by the accompanying virtual audience that surrounded them. The results point to a profound level of plausibility of the experience, though not in the way that the authors expected. The findings add to our understanding of plausibility of virtual environments. This work is funded by the European Research Council (ERC) Advanced Grant Moments in Time in Immersive Virtual Environments (MoTIVE) #742989.

As part of the open sourcing of the Microsoft Rocketbox avatar library for research and academic purposes, here we discuss the importance of rigged avatars for the Virtual and Augmented Reality (VR, AR) research community. Avatars, virtual representations of humans, are widely used in VR applications. Furthermore many research areas ranging from crowd simulation to neuroscience, psychology, or sociology have used avatars to investigate new theories or to demonstrate how they influence human performance and interactions. We divide this paper in two main parts: the first one gives an overview of the different methods available to create and animate avatars. We cover the current main alternatives for face and body animation as well introduce upcoming capture methods. The second part presents the scientific evidence of the utility of using rigged avatars for embodiment but also for applications such as crowd simulation and entertainment. All in all this paper attempts to convey why rigged avatars will be key to the future of VR and its wide adoption. MS-V and MS are funded by NEUROVIRTUAL-AGAUR (2017 SGR 1296). MS-V and Virtual Bodyworks are also supported by the European Union’s Rights, Equality and Citizenship Programme (2014-2020) under Grant Agreement: 881712 (VRperGenere). DB and MS are supported by the European Research Council Advanced Grant MoTIVE #742989. NP was partly funded by the Spanish Ministry of Economy, Industry and Competitiveness under Grant No. TIN2017-88515-C2-1-R.

Understanding human decision making is a key requirement to improve crowd simulation models so that they can better mimic real human behavior. It is often difficult to study human decision making during dangerous situations because of the complexity of the scenarios and situations to be simulated. Immersive virtual reality offers the possibility to carry out such experiments without exposing participants to real danger. In the real world, it has often been observed that people tend to follow others in certain situations (e.g., unfamiliar environments or stressful situations). In this paper, we study human following behavior when it comes to exit choice during an evacuation of a train station. We have carried out immersive VR experiments under different levels of stress (alarm only or alarm plus fire), and we have observed how humans consistently tend to follow the crowd regardless of the levels of stress. Our results show that decision making is strongly influenced by the behavior of the virtual crowd: the more virtual people running, the more likely are participants to simply follow others. The results of this work could improve behavior simulation models during crowd evacuation, and thus build more plausible scenarios for training firefighters. This work was partly funded by the Spanish Ministry of Economy, Industry and Competitiveness under grant number TIN2017-88515-C2-1-R.

Immersive virtual environments have proven to be a plausible platform to be used by multiple disciplines to simulate different types of scenarios and situations at a low cost. When participants are immersed in a virtual environment experience presence, they are more likely to behave as if they were in the real world. Improving the level of realism should provide a more compelling scenario so that users will experience higher levels of presence, and thus be more likely to behave as if they were in the real world. This paper presents preliminary results of an experiment in which participants navigate through two versions of the same scenario with different levels of realism of both the environment and the avatars. Our current results, from a between subjects experiment, show that the reported levels of quality in the visualization are not significantly different, which means that other aspects of the virtual environment and/or avatars must be taken into account in order to improve the perceived level of realism.

Virtual reality is a trending, widely accessible, and contemporary technology of increasing utility to biomedical and health applications. However, most implementations of virtual reality environments are tailored to specific applications. We describe the complete development of a novel, open-source virtual reality environment that is suitable for multipurpose biomedical and healthcare applications. This environment can be interfaced with different hardware and data sources, ranging from gyroscopes to fMRI scanners. The developed environment simulates an immersive (first-person perspective) run in the countryside, in a virtual landscape with various salient features. The utility of the developed VR environment has been validated via two test applications: an application in the context of motor rehabilitation following injury of the lower limbs and an application in the context of real-time functional magnetic resonance imaging neurofeedback, to regulate brain function in specific brain regions of interest. Both applications were tested by pilot subjects that unanimously provided very positive feedback, suggesting that appropriately designed VR environments can indeed be robustly and efficiently used for multiple biomedical purposes. We attribute the versatility of our approach on three principles implicit in the design: selectivity, immersiveness, and adaptability. The software, including both applications, is publicly available free of charge, via a GitHub repository, in support of the Open Science Initiative. Although using this software requires specialized hardware and engineering know-how, we anticipate our contribution to catalyze further progress, interdisciplinary collaborations and replicability, with regards to the usage of virtual reality in biomedical and health applications.

This article reviews the 6-month followup data of a randomized, multicenter, parallel-group study conducted at five clinical sites in three European cities, which compared two second-level treatments for bulimia nervosa (BN) and binge eating disorder (BED): virtual reality-based cue exposure therapy (VR-CET) versus additional cognitive behavioral therapy (A-CBT). Post-treatment outcomes of this study were already published in Ferrer- Garcia et al. (2017) and details of its design can be found at clinicaltrials.gov (identifier: NCT02237300, https:// clinicaltrials.gov). This article focuses on the evolution of symptoms assessed after 6 months of followup in a subgroup of 58 patients from the original study. In this study (Ferrer-Garcia et al., 2017) 64 patients with eating disorders (EDs) (35 with BN and 29 with BED), who still showed active episodes of binge eating by the end of a structured CBT program (first-level treatment), were randomly assigned to one of two second-level treatments (A-CBT or VR-CET). Frequency of binge and purge episodes, and attitudinal features of binge-related EDs (bulimia, drive for thinness, and body dissatisfaction) were assessed before starting the second-level treatment (n = 64), at the end (n = 64), and at 6-month followup (n = 58). Mixed between-within subject analyses of variance were used to compare outcomes of both second-level treatments over time. Although both treatment conditions showed statistically significant improvements at the end and after 6-month followup, obtained reductions were greater after VR-CET, regarding binge and purge episodes, as well as the decrease of selfreported tendency to engage in overeating episodes. Accordingly, abstinence from binge episodes were higher in VR-CET than A-CBT at followup (70 percent vs. 26 percent, respectively; v2 = 11.711, p = 0.001). These results provide further support for the use of VR-CET as an effective second-level intervention for BN and BED treatment-resistant patients.

Body ownership refers to the experience that this body is my body and is closely linked to consciousness. Multisensory integration processes play an important role in body ownership as shown in the rubber hand illusion, which induces the illusory experience that a rubber hand is part of one's own body. Illusions of body ownership can also be experienced in immersive virtual reality (VR), which was used in all three experiments of this thesis. The first experiment of this thesis aimed at investigating some of the underlying mechanisms of body ownership. Specifically we were interested whether the body ownership illusion fluctuates over time and if so, whether these fluctuations are related to spontaneous brain activity. The second experiment aimed at investigating the relation between body ownership illusions and pain perception. Looking at one's own body has been demonstrated to have analgesic properties. This well-known effect in people's real hand has been studied in illusory owned hands with contradictory results. It has been replicated in VR-embodiment, but there are controversial findings in the rubber hand illusion. One crucial difference between the rubber hand illusion and VR-embodiment is that in VR real and virtual hand can be colocated while this is not possible in the rubber hand illusion. We were interested whether the distance between real and surrogate hand can explain controversial findings in the literature. When people experience high levels of body ownership over a virtual body, they can also feel agency over the actions of that virtual body. Agency has been described as result of a matching between predicted and actual sensory feedback of a planned motor action, a process involving motor areas. However, situations in which strong body ownership gives us the illusion of agency, raise the question of the involvement of motor areas in the sense of agency. In the third experiment of this thesis we explored this question in the context of brain computer interfaces (BCI). All together these experiments investigated underlying processes of body ownership and its influences on pain perception and agency. The findings have implications in pain management and neurological rehabilitation.

Seeing one's own body has been reported to have analgesic properties. Analgesia has also been described when seeing an embodied virtual body colocated with the real one. However, there is controversy regarding whether this effect holds true when seeing an illusory-owned body part, such as during the rubber-hand illusion. A critical difference between these paradigms is the distance between the real and surrogate body part. Colocation of the real and surrogate arm is possible in an immersive virtual environment, but not during illusory ownership of a rubber arm. The present study aimed at testing whether the distance between a real and a virtual arm can explain such differences in terms of pain modulation. Using a paradigm of embodiment of a virtual body allowed us to evaluate heat pain thresholds at colocation and at a 30-cm distance between the real and the virtual arm. We observed a significantly higher heat pain threshold at colocation than at a 30-cm distance. The analgesic effects of seeing a virtual colocated arm were eliminated by increasing the distance between the real and the virtual arm, which explains why seeing an illusorily owned rubber arm does not consistently result in analgesia. These findings are relevant for the use of virtual reality in pain management.Perspective: Looking at a virtual body has analgesic properties similar to looking at one's real body. We identify the importance of colocation between a real and a surrogate body for this to occur and thereby resolve a scientific controversy. This information is useful for exploiting immersive virtual reality in pain management. (C) 2017 Published by Elsevier Inc. on behalf of the American Pain Society

Path-finding can become an important bottleneck as both the size of the virtual environments and the number of agents navigating them increase. It is important to develop techniques that can be efficiently applied to any environment independently of its abstract representation. In this paper we present a hierarchical NavMesh representation to speed up path-finding. Hierarchical path-finding (HPA*) has been successfully applied to regular grids, but there is a need to extend the benefits of this method to polygonal navigation meshes. As opposed to regular grids, navigation meshes offer representations with higher accuracy regarding the underlying geometry, while containing a smaller number of cells. Therefore, we present a bottom-up method to create a hierarchical representation based on a multilevel k-way partitioning algorithm (MLkP), annotated with sub-paths that can be accessed online by our Hierarchical NavMesh Path-finding algorithm (HNA*). The algorithm benefits from searching in graphs with a much smaller number of cells, thus performing up to 7.7 times faster than traditional A* over the initial NavMesh. We present results of HNA* over a variety of scenarios and discuss the benefits of the algorithm together with areas for improvement. Graphical abstractDisplay Omitted HighlightsA bottom-up approach to build hierarchical navigation meshes over polygonal maps.Partition with a good balance of number of cells and inter-edges.Real-time path finding over hierarchical polygonal map representations.Discussion of different benchmarks to evaluate the potential of our representation.

This study presents an evaluation of a mobile game with physiologically aware virtual humans as an approach to modulate the participant's affective and physiological state. We developed a mobile version of a virtual reality scenario where the participants were able to interact with virtual human characters through their psychophysiological activity. Music was played in the background of the scenario and, depending on the experimental condition, the virtual humans were initially either barely dancing or dancing very euphorically. The task of the participants was to encourage the apathetic virtual humans to dance or to calm down the frenetically dancing characters, through the modulation of their own mood and physiological activity. Results from our study show that by using this mobile game with the physiologically aware and affective virtual humans the participants were able to emotionally arouse themselves in the Activation condition and were able to relax themselves in the Relaxation condition, during the same session with only a brief break between conditions. The self-reported affective data was also corroborated by the physiological data (heart rate, respiration and skin conductance) which significantly differed between the Activation and Relaxation conditions.

This paper introduces the concept, and discusses the implications of Immersive Journalism, that is the production of news in a form in which people can gain first- 2 person experiences of the events or situation described in news stories. The fundamental idea of Immersive Journalism is to allow the participant, typically represented as a digital avatar, to actually enter a virtually recreated scenario representing the news story. The sense of presence obtained through an immersive system (whether a Cave, head-tracked head-mounted displays (HMD) and online virtual worlds, such as video games and online virtual worlds) affords the participant unprecedented access to the sights and sounds, and possibly feelings and emotions, that accompany the news. The paper surveys current approaches to interactive journalism and the theoretical background supporting claims regarding avatar experience in immersive systems. We also provide a specific demonstration: giving participants the experience of being in an interrogation room in an offshore prison. By both describing current approaches and demonstrating an immersive journalism experience, we open a new avenue for research into how presence can be utilized in the field of news and non-fiction. Keywords Immersive journalism, journalism, interaction, virtual reality, presence, body ownership

Brain–computer interfaces (BCIs) are becoming more and more popular as an input device for virtual worlds and computer games. Depending on their function, a major drawback is the mental workload associated with their use and there is significant effort and training required to effectively control them. In this paper, we present two studies assessing how mental workload of a P300-based BCI affects participants' reported sense of presence in a virtual environment (VE). In the first study, we employ a BCI exploiting the P300 event-related potential (ERP) that allows control of over 200 items in a virtual apartment. In the second study, the BCI is replaced by a gaze-based selection method coupled with wand navigation. In both studies, overall performance is measured and individual presence scores are assessed by means of a short questionnaire. The results suggest that there is no immediate benefit for visualizing events in the VE triggered by the BCI and that no learning about the layout of the virtual space takes place. In order to alleviate this, we propose that future P300-based BCIs in VR are set up so as require users to make some inference about the virtual space so that they become aware of it, which is likely to lead to higher reported presence.

A sign of presence in virtual environments is that people respond to situations and events as if they were real, where response may be considered at many different levels, ranging from unconscious physiological responses through to overt behavior, emotions, and thoughts. In this paper we consider two responses that gave different indications of the onset of presence in a gradually forming environment. Two aspects of the response of people to an immersive virtual environment were recorded: their eye scanpath, and their skin conductance response (SCR). The scenario was formed over a period of 2 min, by introducing an increasing number of its polygons in random order in a head-tracked head-mounted display. For one group of experimental participants (n = 8) the environment formed into one in which they found themselves standing on top of a 3 m high column. For a second group of participants (n = 6) the environment was otherwise the same except that the column was only 1 cm high, so that they would be standing at normal ground level. For a third group of participants (n = 14) the polygons never formed into a meaningful environment. The participants who stood on top of the tall column exhibited a significant decrease in entropy of the eye scanpath and an increase in the number of SCR by 99 s into the scenario, at a time when only 65% of the polygons had been displayed. The ground level participants exhibited a similar decrease in scanpath entropy, but not the increase in SCR. The random scenario grouping did not exhibit this decrease in eye scanpath entropy. A drop in scanpath entropy indicates that the environment had cohered into a meaningful perception. An increase in the rate of SCR indicates the perception of an aversive stimulus. These results suggest that on these two dimensions (scanpath entropy and rate of SCR) participants were responding realistically to the scenario shown in the virtual environment. In addition, the response occurred well before the entire scenario had been displayed, suggesting that once a set of minimal cues exists within a scenario, it is enough to form a meaningful perception. Moreover, at the level of the sympathetic nervous system, the participants who were standing on top of the column exhibited arousal as if their experience might be real. This is an important practical aspect of the concept of presence.

Este artigo apresenta o atual estado da arte da Realidade Aumentada aplicada ao design. São apresentados exemplos de aplicações da Realidade Aumentada em áreas como design de produtos, arquitetura, indústria automotiva, educação e design colaborativo. Também é apresentada uma rápida visão geral sobre as tecnologias envolvidas na criação de aplicações de Realidade Aumentada.

The accommodation of conventional 2D GUIs with virtual environments (VEs) can greatly enhance the possibilities of many VE applications. In this paper we present a variation of the well-known ray-casting technique for fast and accurate selection of 2D widgets over a virtual window immersed into a 3D world. The main idea is to provide a new interaction mode where hand rotations are scaled down so that the ray is constrained to intersect the active virtual window. This is accomplished by changing the control–display ratio between the orientation of the user’s hand and the ray used for selection. Our technique uses a curved representation of the ray providing visual feedback of the orientation of both the input device and the selection ray. We have implemented this technique and evaluated its effectiveness in terms of performance and user preference. Our experiments on a four-sided CAVE indicate that the proposed technique can increase the speed and accuracy of component selection in 2D GUIs immersed into 3D worlds.

Recent advances in 3D scanning technologies have opened new possibilities in a broad range of applications including cultural heritage, medicine, civil engineering, and urban planning. Virtual Reality systems can provide new tools to professionals that want to understand acquired 3D models. In this review paper, we analyze the concept of data comprehension with an emphasis on visualization and inspection tools on immersive setups. We claim that in most application fields, data comprehension requires model measurements, which in turn should be based on the explicit visualization of uncertainty. As 3D digital representations are not faithful, information on their fidelity at local level should be included in the model itself as uncertainty bounds. We propose the concept of Measurable 3D Models as digital models that explicitly encode such local uncertainty bounds. We claim that professionals and experts can strongly benefit from immersive interaction through new specific, fidelity-aware measurement tools, which can facilitate 3D data comprehension. Since noise and processing errors are ubiquitous in acquired datasets, we discuss the estimation, representation, and visualization of data uncertainty. We show that, based on typical user requirements in Cultural Heritage and other domains, application-oriented measuring tools in 3D models must consider uncertainty and local error bounds. We also discuss the requirements of immersive interaction tools for the comprehension of huge 3D and nD datasets acquired from real objects.

This paper is about the major peculiarities and difficulties we encounter when trying to validate research results in fields such as virtual reality (VR) and 3D user interfaces (3DUI). We review the steps in the empirical method and discuss a number of challenges when conducting human-subject experiments. These challenges include the number of independent variables to control to get useful findings, the within-subjects or between-subjects dilemma, hard-to-collect data, experimenter effects, ethical issues, and the lack of background in the community for proper statistical analysis and interpretation of the results. We show that experiments involving human-subjects hinder the adoption of traditional experimental principles (comparison, repeatability, reproducibility, justification and explanation) and propose some ideas to improve the reliability of findings in VR and 3DUI disciplines.

The aim of this study was to assess the usefulness of virtual environments representing situations that are emotionally significant to subjects with eating disorders (ED). These environments may be applied with both evaluative and therapeutic aims and in simulation procedures to carry out a range of experimental studies. This paper is part of a wider research project analyzing the influence of the situation to which subjects are exposed on their performance on body image estimation tasks. Thirty female patients with eating disorders were exposed to six virtual environments: a living-room (neutral situation), a kitchen with high-calorie food, a kitchen with low-calorie food, a restaurant with high-calorie food, a restaurant with low-calorie food, and a swimming-pool. After exposure to each environment the STAI-S (a measurement of state anxiety) and the CDB (a measurement of depression) were administered to all subjects. The results show that virtual reality instruments are particularly useful for simulating everyday situations that may provoke emotional reactions such as anxiety and depression, in patients with ED. Virtual environments in which subjects are obliged to ingest high-calorie food provoke the highest levels of state anxiety and depression.

In this study, we describe the implementation and evaluation of an experiment with Augmented Reality (AR) technology in the visualization of 3D models and the presentation of architectural projects by students of architecture and building engineering. The proposal is based on the premise that the technology used in AR, such as mobile devices, is familiar to the student. When used in a collaborative manner, the technology is able to achieve a greater level of direct engagement with the proposed content, thereby improving academic outcomes. The objective was to assess the feasibility of using AR on mobile devices in educational environments and to investigate the relationship between the usability of the tool, student participation, and the improvement in academic performance after using AR. The validation was performed through a case study in which students were able to experience a virtual construction process overlapped onto real environments. Results were obtained by students' pre-tests and post-tests. In line with our assumptions, the use of mobile devices in the classroom is highly correlated with motivation, and there is a significant correlation with academic achievement. However, the difficulty of using and generating content is a complex factor that suggests difficulty when implementing more complicated models. (C) 2013 Elsevier Ltd. All rights reserved.

Trabajo presentado a la Virtual Reality International Conference (VRIC) celebrada del 9 al 11 de abril de 2014 en Laval (Francia).-- et al., The development of systems that allow multimodal interpretation of human-machine interaction is crucial to advance our understanding and validation of theoretical models of user behavior. In particular, a system capable of collecting, perceiving and interpreting unconscious behavior can provide rich contextual information for an interactive system. One possible application for such a system is in the exploration of complex data through immersion, where massive amounts of data are generated every day both by humans and computer processes that digitize information at different scales and resolutions thus exceeding our processing capacity. We need tools that accelerate our understanding and generation of hypotheses over the datasets, guide our searches and prevent data overload. We describe XIM-engine, a bio-inspired software framework designed to capture and analyze multi-modal human behavior in an immersive environment. The framework allows performing studies that can advance our understanding on the use of conscious and unconscious reactions in interactive systems., The work described in this paper has been supported by the European Commission, Seventh Framework Programme under the research grant CEEDs (FP7-ICT- 258749).

There is evidence that virtual reality (VR) pain distraction is effective at improving pain-related outcomes. However, more research is needed to investigate VR environments with other pain-related goals. The main aim of this study was to compare the differential effects of two VR environments on a set of pain-related and cognitive variables during a cold pressor experiment. One of these environments aimed to distract attention away from pain (VRD), whereas the other was designed to enhance pain control (VRC). Participants were 77 psychology students, who were randomly assigned to one of the following three conditions during the cold pressor experiment: (a) VRD, (b) VRC, or (c) Non-VR (control condition). Data were collected regarding both pain-related variables (intensity, tolerance, threshold, time perception, and pain sensitivity range) and cognitive variables (self-efficacy and catastrophizing). Results showed that in comparison with the control condition, the VRC intervention significantly increased pain tolerance, the pain sensitivity range, and the degree of time underestimation. It also increased self-efficacy in tolerating pain and led to a reduction in reported helplessness. The VRD intervention significantly increased the pain threshold and pain tolerance in comparison with the control condition, but it did not affect any of the cognitive variables. Overall, the intervention designed to enhance control seems to have a greater effect on the cognitive variables assessed. Although these results need to be replicated in further studies, the findings suggest that the VRC intervention has considerable potential in terms of increasing self-efficacy and modifying the negative thoughts that commonly accompany pain problems.

This work investigates novel alternative means of interaction in a virtual environment (VE). We analyze whether humans can remap established body functions to learn to interact with digital information in an environment that is cross-sensory by nature and uses vocal utterances in order to influence (abstract) virtual objects. We thus establish a correlation among learning, control of the interface, and the perceived sense of presence in the VE. The application enables intuitive interaction by mapping actions (the prosodic aspects of the human voice) to a certain response (i.e., visualization). A series of single-user and multiuser studies shows that users can gain control of the intuitive interface and learn to adapt to new and previously unseen tasks in VEs. Despite the abstract nature of the presented environment, presence scores were generally very high.

Immersive virtual reality (IVR) typically generates the illusion in participants that they are in the displayed virtual scene where they can experience and interact in events as if they were really happening. Teleoperator (TO) systems place people at a remote physical destination embodied as a robotic device, and where typically participants have the sensation of being at the destination, with the ability to interact with entities there. In this paper, we show how to combine IVR and TO to allow a new class of application. The participant in the IVR is represented in the destination by a physical robot (TO) and simultaneously the remote place and entities within it are represented to the participant in the IVR. Hence, the IVR participant has a normal virtual reality experience, but where his or her actions and behaviour control the remote robot and can therefore have physical consequences. Here, we show how such a system can be deployed to allow a human and a rat to operate together, but the human interacting with the rat on a human scale, and the rat interacting with the human on the rat scale. The human is represented in a rat arena by a small robot that is slaved to the human"s movements, whereas the tracked rat is represented to the human in the virtual reality by a humanoid avatar. We describe the system and also a study that was designed to test whether humans can successfully play a game with the rat. The results show that the system functioned well and that the humans were able to interact with the rat to fulfil the tasks of the game. This system opens up the possibility of new applications in the life sciences involving participant observation of and interaction with animals but at human scale.

When a rubber hand is placed on a table top in a plausible position as if part of a person"s body, and is stroked synchronously with the person"s corresponding hidden real hand, an illusion of ownership over the rubber hand can occur (Botvinick and Cohen 1998). A similar result has been found with respect to a virtual hand portrayed in a virtual environment, a virtual hand illusion (Slater et al. 2008). The conditions under which these illusions occur have been the subject of considerable study. Here we exploited the flexibility of virtual reality to examine four contributory factors: visuo-tactile synchrony while stroking the virtual and the real arms, body continuity, alignment between the real and virtual arms, and the distance between them. We carried out three experiments on a total of 32 participants where these factors were varied. The results show that the subjective illusion of ownership over the virtual arm and the time to evoke this illusion are highly dependent on synchronous visuo-tactile stimulation and on connectivity of the virtual arm with the rest of the virtual body. The alignment between the real and virtual arms and the distance between these were less important. It was found that proprioceptive drift was not a sensitive measure of the illusion, but was only related to the distance between the real and virtual arms.

Multi-user virtual reality systems enable natural collaboration in share virtual worlds. Users can talk to each other, gesture and point into the virtual scenery as if it were real. As in reality, refer ring to objects by pointing results often in a situation whereon objects are occluded from the other users’ viewpoints. While in reality this problem can only be solved by adapting the viewing position, specialized individual views of the shared virtual scene enable various other solutions. As one such solution we propose show-through techniques to make sure that the objects one is pointing to can always be seen by others. We first study the impact of such augmented viewing techniques on the spatial understanding of the scene, the rapidity of mutual information exchange as well as the proxemic behavior of users. To this end we conducted a user study in a co-located stereoscopic multi-user setup. Our study revealed advantages for show- through techniques interms of comfort, user acceptance and compliance to social protocols while spatial understanding and mutual information exchange is retained. Motivated by these results we further analyze whether show-through techniques may also be beneficial in distributed virtual environments.We investigated a distributed setup for two users, each participant having its own display screen and a minimalist avatar representation for each participant. In such a configuration there is a lack of mutual awareness, which hinders the understanding of each other’s pointing gestures and decreases the relevance of social protocols interms of proxemic behavior. Nevertheless, we found that show-through techniques can improve collaborative interaction tasks even in such situations

BACKGROUND: Body change illusions have been of great interest in recent years for the understanding of how the brain represents the body. Appropriate multisensory stimulation can induce an illusion of ownership over a rubber or virtual arm, simple types of out-of-the-body experiences, and even ownership with respect to an alternate whole body. Here we use immersive virtual reality to investigate whether the illusion of a dramatic increase in belly size can be induced in males through (a) first person perspective position (b) synchronous visual-motor correlation between real and virtual arm movements, and (c) self-induced synchronous visual-tactile stimulation in the stomach area. METHODOLOGY: Twenty two participants entered into a virtual reality (VR) delivered through a stereo head-tracked wide field-of-view head-mounted display. They saw from a first person perspective a virtual body substituting their own that had an inflated belly. For four minutes they repeatedly prodded their real belly with a rod that had a virtual counterpart that they saw in the VR. There was a synchronous condition where their prodding movements were synchronous with what they felt and saw and an asynchronous condition where this was not the case. The experiment was repeated twice for each participant in counter-balanced order. Responses were measured by questionnaire, and also a comparison of before and after self-estimates of belly size produced by direct visual manipulation of the virtual body seen from the first person perspective. CONCLUSIONS: The results show that first person perspective of a virtual body that substitutes for the own body in virtual reality, together with synchronous multisensory stimulation can temporarily produce changes in body representation towards the larger belly size. This was demonstrated by (a) questionnaire results, (b) the difference between the self-estimated belly size, judged from a first person perspective, after and before the experimental manipulation, and (c) significant positive correlations between these two measures. We discuss this result in the general context of body ownership illusions, and suggest applications including treatment for body size distortion illnesses.

The aim of this article was to study the effect of virtual-reality exposure to situations that are emotionally significant for patients with eating disorders (ED) on the stability of body-image distortion and body-image dissatisfaction. A total of 85 ED patients and 108 non-ED students were randomly exposed to four experimental virtual environments: a kitchen with low-calorie food, a kitchen with high-calorie food, a restaurant with low-calorie food, and a restaurant with high-calorie food. In the interval between the presentation of each situation, body-image distortion and body-image dissatisfaction were assessed. Several 2 x 2 x 2 repeated measures analyses of variance (high-calorie vs. low-calorie food x presence vs. absence of people x ED group vs. control group) showed that ED participants had significantly higher levels of body-image distortion and body dissatisfaction after eating high-calorie food than after eating low-calorie food, while control participants reported a similar body image in all situations. The results suggest that body-image distortion and body-image dissatisfaction show both trait and state features. On the one hand, ED patients show a general predisposition to overestimate their body size and to feel more dissatisfied with their body image than controls. On the other hand, these body-image disturbances fluctuate when participants are exposed to virtual situations that are emotionally relevant for them.

This paper reports an experiment that investigated people's body ownership of an avatar that was observed in a virtual mirror. Twenty subjects were recruited in a within-groups study where 10 first experienced a virtual character that synchronously reflected their upper-body movements as seen in a virtual mirror, and then an asynchronous condition where the mirror avatar displayed prerecorded actions, unrelated to those of the participant. The other 10 subjects experienced the conditions in the opposite order. In both conditions the participant could carry out actions that led to elevation above ground level, as seen from their first person perspective and correspondingly in the mirror. A rotating virtual fan eventually descended to 2m above the ground. The hypothesis was that synchronous mirror reflection would result in higher subjective sense of ownership. A questionnaire analysis showed that the body ownership illusion was significantly greater for the synchronous than asynchronous condition. Additionally participants in the synchronous condition avoided collision with the descending fan significantly more often than those in the asynchronous condition. The results of this experiment are put into context within similar experiments on multisensory correlation and body ownership within cognitive neuroscience.

The CINeSPACE (www.cinespace.eu) project allows tourists to access the rich cultural heritage of urban environments by literally morphing the user into the past through the use of multimedia archives. Tourists use the device which includes both a PDA type of device with a GIS interface displayed on a touch screen to help the user navigate and select multimedia content, and video binoculars to create the augmented reality effects. In addition to this mode of interaction, a survey of Mixed Reality user interaction paradigms will be presented. A key feature of Mixed Reality user interfaces is the object identification and annotation methods available to the user, of which a survey, including a review of the GeoConcepts ontology annotation methodology used in the CINeSPACE device, will be presented.

We discuss three experiments that investigate how virtual limbs and bodies can come to feel like real limbs and bodies. The first experiment shows that an illusion of ownership of a virtual arm appearing to project out of a person’s shoulder can be produced by tactile stimulation on a person’s hidden real hand and synchronous stimulation on the seen virtual hand. The second shows that the illusion can be produced by synchronous movement of the person’s hidden real hand and a virtual hand. The third shows that a weaker form of the illusion can be produced when a brain-computer interface is employed to move the virtual hand by means of motor imagery without any tactile stimulation. We discuss related studies that indicate that the ownership illusion may be generated for an entire body. This has important implications for the scientific understanding of body ownership and several practical applications.

Outgoing

The integration of the human brain with computers is an interesting new area of applied neuroscience, where one application is replacement of a person’s real body by a virtual representation. Here we demonstrate that a virtual limb can be made to feel part of your body if appropriate multisensory correlations are provided. We report an illusion that is invoked through tactile stimulation on a person’s hidden real right hand with synchronous virtual visual stimulation on an aligned 3D stereo virtual arm projecting horizontally out of their shoulder. An experiment with 21 male participants showed displacement of ownership towards the virtual hand, as illustrated by questionnaire responses and proprioceptive drift. A control experiment with asynchronous tapping was carried out with a different set of 20 male participants who did not experience the illusion. After 5 minutes of stimulation the virtual arm rotated. Evidence suggests that the extent of the illusion was also correlated with the degree of muscle activity onset in the right arm as measured by EMG during this period that the arm was rotating, for the synchronous but not the asynchronous condition. A completely virtual object can therefore be experienced as part of one’s self, which opens up the possibility that an entire virtual body could be felt as one’s own in future virtual reality applications or online games, and be an invaluable tool for the understanding of the brain mechanisms underlying body ownership.

We derive a complete component framework for transforming standalone virtual reality (VR) applications into fullfledged multithreaded collaborative virtual reality environments (CVREs), after characterizing existing implementations into a feature-rich superset. Our main contribution is placing over the existing VR tool a very concise and extensible class framework as an add-on component that provides emerging collaboration features. The enhancements include: a scalable arbitrated peer-to-peer topology for scene sharing; multi-threaded components for graphics rendering, user interaction and network communications; a streaming message protocol for client communications; a collaborative user interface model for session handling; and interchangeable user roles with multicamera perspectives, avatar awareness and shared 3D annotations. We validate the framework by converting the existing ALICE VR Navigator into complete CVRE, with experimental results showing good performance in the collaborative inspection and manipulation of complex models.

This paper describes a new virtual reality system designed to be small enough to be totally portable. It is a semiimmersive interaction system based on a movable stereoscopic projection screen with a tracking system to capture the movement of the screen with respect to the virtual model. The system can be used for cooperative inspection of very complex computer-aided design environments, allowing very simple interaction among users and designers at distant locations.

Cognitive neuroscientists have discovered through various experiments that our body representation is surprisingly flexible. Multisensory body illusions work well in immersive virtual reality, and recent findings suggest that they offer both a powerful tool for neuroscience and a new path for future exploration. The first Web extra at http://youtu.be/rf39t1iV0Ao is a video showing how embodying adults in a virtual child's body can cause overestimation of object sizes and implicit attitude changes. The second Web extra at http://youtu.be/H9-il4cx2mA is a video showing how embodying adults in virtual reality with different avatars can affect their drumming performance. The third Web extra at http://youtu.be/DEofSgdv3Nc is a video showing embodiment in a virtual body that "substitutes" the person's own body. This experiment suggested that embodying light-skinned people in a dark-skinned virtual body led to a reduction in their implicit racial bias.

PUBLISHED, Major challenges must be tackled for brain-computer interfaces to mature into an established communications medium for VR applications, which will range from basic neuroscience studies to developing optimal peripherals and mental gamepads and more efficient brain-signal processing techniques.

Aquest Treball de Final de Grau anomenat Manipulació d’Objectes en Aplicacions de Realitat Virtual: Leap Motion té com a objectius, d’una banda, investigar les noves tecnologies d’interacció persona-computador amb la funció de traslladar a l’usuari a una experiència més profunda i propera a la realitat en l’àmbit del joc. D’altra banda, crear una aplicació que contingui escenes 3D en les quals el propi usuari pugui interactuar amb els objectes mitjançant la representació de les seves mans. En els últims temps, el mercat del hardware ha estat portant una àmplia gama de tecnologies basades en noves formes d’interacció de l’usuari amb la computadora. En aquest projecte s’utilitzarà el software Unity3D per la creació de l’aplicació i el dispositiu Leap Motion pel control i seguiment de les mans de l’usuari. Aquest dispositiu està dissenyat per al reconeixement 3D gestual de les nostres mans. Per tant, la versatilitat que ofereix aquesta tecnologia és molt gran, ja que hi ha moltes aplicacions de camps molts diferents en les quals l’ús de gests pot facilitar la interacció persona-màquina. La implementació d’aquest projecte es divideix en diverses línies de desenvolupament: s’han dissenyat 4 escenes virtuals, de les quals cadascuna té una finalitat diferent, per demostrar que la connexió de Unity amb el Leap Motion és possible. La primera escena s’ha programat per que el Leap Motion detecti el que es coneix amb el nom de “pinch”, o pessic en català, que farem amb les mans per agafar objectes i moure’ls de lloc. Les altres tres escenes, en canvi, s’han configurat per que en detectar un gest determinat, ja sigui el moviment d’un o varis dits, del palmell de la mà, o qualsevol altre gest, realitzin una certa acció. Per poder visualitzar les escenes, s’ha dissenyat una interfície d’usuari (UI) amb un menú per accedir més còmodament a l’aplicació. Un cop finalitzat el treball, es pot concloure que es poden crear fàcilment Apps de realitat virtual utilitzant el software Unity i el sensor Leap Motion, i que existeixen infinites possibles aplicacions en múltiples sectors. S’ha provat l’aplicació i s’ha demostrat que es pot interactuar amb la pantalla de l’ordinador sense haver de fer ús del ratolí o del teclat, simplement amb el moviment de les nostres mans.

What does it feel like to own, to control, and to be inside a body? The multidimensional nature of this experience together with the continuous presence of one's biological body, render both theoretical and experimental approaches problematic. Nevertheless, exploitation of immersive virtual reality has allowed a reframing of this question to whether it is possible to experience the same sensations towards a virtual body inside an immersive virtual environment as toward the biological body, and if so, to what extent. The current paper addresses these issues by referring to the Sense of Embodiment (SoE). Due to the conceptual confusion around this sense, we provide a working definition which states that SoE consists of three subcomponents: the sense of self-location, the sense of agency, and the sense of body ownership. Under this proposed structure, measures and experimental manipulations reported in the literature are reviewed and related challenges are outlined. Finally, future experimental studies are proposed to overcome those challenges, toward deepening the concept of SoE and enhancing it in virtual applications.

Background: Altering the normal association between touch and its visual correlate can result in the illusory perception of a fake limb as part of our own body. Thus, when touch is seen to be applied to a rubber hand while felt synchronously on the corresponding hidden real hand, an illusion of ownership of the rubber hand usually occurs. The illusion has also been demonstrated using visuomotor correlation between the movements of the hidden real hand and the seen fake hand. This type of paradigm has been used with respect to the whole body generating out-of-the-body and body substitution illusions. However, such studies have only ever manipulated a single factor and although they used a form of virtual reality have not exploited the power of immersive virtual reality (IVR) to produce radical transformations in body ownership. Principal Findings: Here we show that a first person perspective of a life-sized virtual human female body that appears to substitute the male subjects' own bodies was sufficient to generate a body transfer illusion. This was demonstrated subjectively by questionnaire and physiologically through heart-rate deceleration in response to a threat to the virtual body. This finding is in contrast to earlier experimental studies that assume visuotactile synchrony to be the critical contributory factor in ownership illusions. Our finding was possible because IVR allowed us to use a novel experimental design for this type of problem with three independent binary factors: (i) perspective position (first or third), (ii) synchronous or asynchronous mirror reflections and (iii) synchrony or asynchrony between felt and seen touch. Conclusions: The results support the notion that bottom-up perceptual mechanisms can temporarily override top down knowledge resulting in a radical illusion of transfer of body ownership. The research also illustrates immersive virtual reality as a powerful tool in the study of body representation and experience, since it supports experimental manipulations that would otherwise be infeasible, with the technology being mature enough to represent human bodies and their motion. © 2010 Slater et al., This research was supported by the Integrated Project PRESENCCIA funded under the European Union’s Sixth Framework Program, Future and Emerging Technologies (FET), Contract Number 27731. http://cordis.europa.eu/ist/fet/pr.htm. The work was also partially supported by MS’s European Research Council grant TRAVERSE (227985).