Haut PDF How real is movement in virtual environments ?

How real is movement in virtual environments ?

How real is movement in virtual environments ?

NOTICE This document was digitized by the Records Management & Archives Division of Université de Montréal. The author of this thesis or dissertation has granted a nonexclusive license allowing Université de Montréal to reproduce and publish the document, in part or in whole, and in any format, solely for noncommercial educational and research purposes.

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Modélisation des environnements virtuels urbains dédiés à
la simulation du mouvement des piétons.
Modelling virtual urban environments dedicated to the simulation of
pedestrian movement.

Modélisation des environnements virtuels urbains dédiés à la simulation du mouvement des piétons. Modelling virtual urban environments dedicated to the simulation of pedestrian movement.

From space syntax point of view, there are two main approaches that have been developed to address the issue of pedestrian movement analysis, modelling and simulation. The first approach defined as ‘configurational analysis’ – to cover methods based on representing and quantifying aspects of the spatial configuration or morphology of the environment within which movement takes place, and the second ‘pedestrian simulation’ – to cover methods that seek to represent the individual pedestrian or the pedestrian population, where the aim is frequently to populate environments with realistic individual virtual humans, and crowds. Supporting the first approach Turner & Penn (2002) have developed an agent simulation architecture based on the visibility graph analysis, in which agents have access to pre- computed information about what is visible from any given location in the map. In addition information can be attached to the nodes of the graph describing attributes of the visible nodes. Amongst these attributes are space syntax measures of the configuration properties of the graph at each node, but they can also attribute information regarding goods on display or other static aspects of the environment. They call this architecture an ‘exosomatic visual architecture’ since it in effect provides agents with a form of exosomatic (outside the body) memory common to all agents in an environment.
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VERA: Virtual Environments Recording Attention

VERA: Virtual Environments Recording Attention

In everyday life, ADHD is characterized by several draw- backs that affect the patients’ life as explained by Caci et al. 2014 [9]: impairments in school, social life (with friends, classmates and parents), activities, etc. To reduce these symp- toms, different methods have been developed: 1) Medication by daily intake of methylphenidate, nevertheless in addition to the controversial aspects that medicalizing children involves, it is not effective for 20 to 30% of the patients according to Cueli et al. 2019 [11]; 2) Behavioural treatments to help the detection and reduction of the behaviours caused by the symptoms, but this method is more expensive and binding; 3) Neurofeedback (NF) a method consisting of a real-time representation of the brain activity (in an understandable form) to teach how to self-regulate specific brain functions, this method is already used for treatment of phobia (Zilverstand et al. 2015 [32]), Autistic Spectrum Disorder (Coben et al. 2010 [10]) or Anxiety (Schoneveld et al. 2016 [27]).
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Adaptive Navigation for Virtual Environments

Adaptive Navigation for Virtual Environments

∗ e-mail: fernando.argelaguet sanz@inria.fr 2 P REVIOUS W ORK 2.1 Speed Control The speed control of a navigation technique is linked with the scale of the environment and the user’s preferences. While the scale of the environment provides a threshold for the maximum allowed speed, users, through the navigation interface, are able to adjust the speed using a number of input commands [4] and speed map- pings [1]. In terms of speed, we can distinguish the linear com- ponent of the motion (tangential speed) and the rotational compo- nent (rotational speed). If no speed adaptation is available, and if the scale of the environment is known a priori, then the max- imum speed can be properly adjusted by the interface designer. In addition, if we are navigating through a real scale model, the tangential speed can be bounded to human walking speed (0.6m/s to 1.4m/s) [7]. Moreover, to better resemble the human walking speed, when rotational speed increases, tangential speed should be decreased [7].
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Virtual navigation tested on a mobile app is predictive of real-world wayfinding navigation performance

Virtual navigation tested on a mobile app is predictive of real-world wayfinding navigation performance

We found a significant male advantage in the wayfinding task in both real world and virtual environments, although weaker in the real world. This difference in effect size between the two environments couldn’t be explained by males being more familiar with video games, as sug- gested in a previous study [ 34 ] for three reasons. First, our male and female participants reported playing video games the same average duration per week (2.95 vs 2.99 hours per week). Second, when using gender and time playing video games (VGT) as covariates in a lin- ear model to predict wayfinding performance in the real world (resp. in the virtual environ- ment), gender came out as a significant predictor, but not VGT. Third, we found a very weak correlation coefficient (skipped Pearson’s r = 0.06) between the performance at the real-world wayfinding task and at the first training Sea Hero Quest level, which did not require any spatial ability (the endpoint being visible from the start). The strength of the correlation increased with the difficulty of the video game level (up to r = 0.44 in level 43), indicating that Sea Hero Quest does not merely capture video gaming skills. The discrepancy with [ 34 ] might stem from the difference between tasks, Richardson et al.’s task being closer to the path integration task than to the wayfinding task discussed in this paragraph. The underlying causes of gender differences in spatial ability are still debated in the literature and include sex hormones varia- tion, evolution, differences in self-confidence and anxiety [ 18 ]. In a previous paper based on the global video game dataset, we showed that gender differences in spatial ability measured in the game correlate with gender differences in the society measured with the Gender Gap Index (World Economic Forum) [ 13 ].
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Towards a Model of User Experience in Immersive Virtual Environments

Towards a Model of User Experience in Immersive Virtual Environments

2.2.2. Presence, Immersion, and Engagement. Immersion is a component defined as the “objective level of sensory fidelity a virtual reality system provides” ([20], p. 38). The immersive dimension in a virtual environment is created by “complex technologies that replace real-world sensory information with synthetic stimuli” ([20], p. 36). Engagement is a component defined as “a psychological state experienced because of focus- ing one’s energy and attention on a coherent set of stimuli or meaningfully related activities and events” ([21], p. 227). Following the Witmer and Singer’s approach, immersion and engagement are two elements that contribute to the idea of presence [21]. Shin et al. [10] consider immersion as clearly related to the widely research concept of presence. Hence, we may hypothesize that the sense of presence enhances the degree of engagement and the feeling of immersion; the same way the two components enhance presence (Hypothesis 2). 2.2.3. Flow, Usability, Skill, and Emotion. Usability is a component defined as the ease of using (i.e., efficiency, effectiveness, and satisfaction) the virtual environment. Skill is a component defined as the knowledge the user gain in mastering his activity in the virtual environment. Emo- tion is a component defined as the subjective feelings (i.e., joy, pleasure, satisfaction, frustration, disappointment, and anxiety) of the user in the virtual environment that varies with his prior experience with virtual reality [22]. According to Shin et al. [10] users feeling present and in a state of flow may want to perceive what is useful and easy to use and thus feel satisfied. Given the widely accepted factors, perceived usefulness, perceived ease of use, and satisfaction can be indicators of perceived usability [10]. Cheng et al. [9] asserted that the user can derive emotions from the human- machine interaction experience and that strong flow creates this emotional state. They also suggest that skill affects flow. In fact, the state of flow results from an equilibrium between the user’s perceived skill and the challenge given. Thus, we
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Roles in Collaborative Virtual Environments for Training

Roles in Collaborative Virtual Environments for Training

1. Introduction One of the main advantages of training using Virtual Reality is to provide multiple situations using one scene. These vari- ations can come from changes in the scenario, and therefore in the events that occur in the environment such as a proce- dure. They can also come from changes in the organisation and definition of the actors: what they are able to do in the environment depending on the state how the simulation is unfolding. The common solution is to integrate the notion of role to define the position of the actors in the team. In this paper we focus on the modelling of the role of the ac- tors to provide multiple training situations using one scene and one scenario. We illustrate our discussion using the case of a Collaborative Virtual Environment for the Training of a neurosurgery procedure (see Figure 1 ).
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Homing by triangle completion in consumer-oriented virtual reality environments

Homing by triangle completion in consumer-oriented virtual reality environments

A BSTRACT Homing is a fundamental task which plays a vital role in spatial nav- igation. Its performance depends on the computation of a homing vector, where human beings can use simultaneously two different cognitive strategies: an online strategy based on the self-motion cues known as path integration (PI), and an offline strategy based on the spatial image of the path called piloting. Studies using virtual reality environments (VE) have shown that human being can perform hom- ing tasks with acceptable performance. However, in these studies, subjects were able to walk naturally across large tracking areas, or researchers provided them with high-end large-immersive displays. Unfortunately, these configurations are far from current consumer- oriented devices, and very little is known about how their limitations can influence these cognitive processes. Using a triangle comple- tion paradigm, we assessed homing tasks in two consumer-oriented displays (an HTC Vive and a GearVR) and two consumer-oriented interaction devices (a Virtuix Omni Treadmill and a Touchpad Con- trol). Our results show that when locomotion is available (treadmill condition), there exist significant effects regarding display and path complexity. In contrast, when locomotion is restricted (touchpad condition), some effects on path complexity were found. Thus, some future research directions are therefore proposed.
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Haptic communication to enhance collaboration in virtual environments

Haptic communication to enhance collaboration in virtual environments

We are continuing to study the haptic communication paradigm in collaborative virtual environments. This paradigm can be used in a system that helps two distant users to co-manipulate the same tool. This ongoing work will contribute to better understand collaboration using haptic interactions and how the common frame of reference is developed through the haptic channel. The WYFIWIF paradigm can be used in other learning scenarios. One can image a learning system in which expert radiologist can supervise novices during the practice. This scenario can help the novices to be more active during the learning process. Furthermore, since the teacher feels the novices’ actions, he can give more practical advices to the students. This can permit to design more efficient systems for learning motor skills.
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OpenViBE: An Open-Source Software Platform to Design, Test and Use Brain-Computer Interfaces in Real and Virtual Environments

OpenViBE: An Open-Source Software Platform to Design, Test and Use Brain-Computer Interfaces in Real and Virtual Environments

skills to design a new real-time BCI from scratch. Furthermore, their modularity is coarser (except for BioSig), hence restricting the range of possible designs. OpenViBE is also portable, independent of the hardware or software and is en- tirely based on free and open-source softwares. In comparison, among other real-

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Automatic Generation of Urban Virtual Environments

Automatic Generation of Urban Virtual Environments

Models of 3D cities, in an effort to get closer to the real ones, are becoming increasingly complex in terms of spatial and thematic structures. In order to store all this information, standardized data models, ensur- ing consistent and inter-operable data structure, have to be built. On the other hand, all the progress made in computer graphics and hardware enables 3D virtual worlds to be more and more complex visually speaking. As visual quality of video games improves with each new generation of graphics hardware, the user expectations increases proportionally. To manage the display of this quantity of data, a possible alternative to manually cre- ating large amounts of models is to apply procedural techniques, along with the use of a few models. Indeed, a complex city containing many different models would take a long time to build manually, and to minimize the costs of world’s creation, the generation of objects with a procedural approach, not only adds controllable randomness to the world but also gives varied results. Our work is focused on creating a hierarchical database model that contains the basic elements of an urban envi- ronment, and from these data, our system will automat-
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A 6-D Mouse for Virtual Environments

A 6-D Mouse for Virtual Environments

Figure 1.1: Kumar’s LED pattern 2 Mouse modifications We only made a few changes to Kumar’s mouse, mainly to adapt it to the setting of a virtual real- ity workbench. When a user is operating in a virtual world, any visual cues from the real world can con- tribute to break the state of immersion. That is why we chose to move the light emitting diodes (LEDs) from top to the side of the device. That way, most of the time, the user won’t see light in his field of view which would cause distraction from the task at hand. Also we covered the device with black material to make it harder for human eyes to detect it in a dark environment. It is then convenient for the user and other persons in the room that will not see the device as well.
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Bimanual haptic interaction with virtual environments

Bimanual haptic interaction with virtual environments

To this day, VR applications have most commonly used the visual and auditive modal- ities as ways to provide feedback from the VE to the user. This may prove sufficient to provide a sufficient level of immersion when the experience does not require direct inter- action with the VE, such as in virtual tours. However, these sensorial modalities alone may fall short when actual interaction between the user’s body and virtual objects is in- volved. Indeed, when we interact directly with objects in real life, a third sense is heavily involved in the perception of that interaction: the haptic sense, which encompasses two complementary senses. First, the tactile sense operates at the skin level, and allows to feel surfaces and textures. Secondly, the proprioceptive or kinesthetic sense is mediated by the inner ear as well as receptors inside the muscles and tendons, and is related to the perception of balance and posture of the different parts of the body relative to each other. When our hands interact with objects, local forces of contact and texture of the object are perceived through the tactile sense, while overall shape and properties like elasticity are perceived through the kinesthetic sense.
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Automatic Generation of Urban Virtual Environments

Automatic Generation of Urban Virtual Environments

Models of 3D cities, in an effort to get closer to the real ones, are becoming increasingly complex in terms of spatial and thematic structures. In order to store all this information, standardized data models, ensur- ing consistent and inter-operable data structure, have to be built. On the other hand, all the progress made in computer graphics and hardware enables 3D virtual worlds to be more and more complex visually speaking. As visual quality of video games improves with each new generation of graphics hardware, the user expectations increases proportionally. To manage the display of this quantity of data, a possible alternative to manually cre- ating large amounts of models is to apply procedural techniques, along with the use of a few models. Indeed, a complex city containing many different models would take a long time to build manually, and to minimize the costs of world’s creation, the generation of objects with a procedural approach, not only adds controllable randomness to the world but also gives varied results. Our work is focused on creating a hierarchical database model that contains the basic elements of an urban envi- ronment, and from these data, our system will automat-
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Personalisation of learning in virtual learning environments

Personalisation of learning in virtual learning environments

Tracked Data for Instructors and Researchers Some authors expressed interest for the exploitation of different kinds of interaction footprints by researchers [48, 49]. Others speculated about its benefit for instructors [50]. Among them, Nagi & Suesawaluk [51] recommended tutors to make use of the students data tracked by the Moodle eLearning platform in order to better regulate their courses. With a tool called CourseVis, Mazza & Dimitrova [52] took student tracking data collected by content management systems and generated graphical representations useful to instructors to gain an understanding of what is happening in distance learning classes. This work lead to the production of Gismo, a tool managing the visualization of data tracked in Moodle [53]. In a similar vein and on the same platform, Zhang et al. [54] developed a VLE log analysis tool, called Moodog, to track students’ online learning activities. The goals of Moodog were twofold: first, to provide instructors with insight about how students interact with online course materials, and second, to allow students to easily compare their own progress to others in the class. The latter objective sounded congruent with the approach defined in this article. However the authors eventually postponed its achievement to a subsequent study. Scheuer and Zinn [55] developed an interesting tracking system called the Student Inspector. In their conclusion, they only evoked the possibility to open the tool to students.
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Image-Based Navigation in Real Environments Using Panoramas

Image-Based Navigation in Real Environments Using Panoramas

Institute for Information Technology, National Research Council of Canada Abstract – We present a system for virtual navigation in real environments using image-based panorama rendering. Multiple overlapping images are captured using a Point Grey Ladybug camera and a single cube-aligned panorama image is generated for each capture location. Panorama locations are connected in a graph topology and registered with a 2D map for navigation. A real-time image-based viewer renders individual 360-degree panoramas using graphics hardware acceleration. Real-world navigation is performed by traversing the graph and loading new panorama images. The system contains a user-friendly interface and supports standard input and display or a head-mounted display with an inertial tracking device.
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The virtual museum: virtualisation of real historical environments and artifacts and three-dimensional shape-based searching

The virtual museum: virtualisation of real historical environments and artifacts and three-dimensional shape-based searching

not a unit vector since it has a length. The statistical distribution of the cord orientations can be represented by three histograms: two for the angles and one for the radius. This radius histogram is scale-dependent but it can be made scale-independent, by normalising the radius. In order to process the data two basic problems need to be solved: the choice of the metric [1] and the number of channels or bins in each histogram. In order to determine the outcome of the search, the closest histograms to the reference histogram has to be found in the multidimensional space. A recent study [2] has shown that the Hamming and the Euclidean distance are the sole metrics that should be used. Any other metric is meaningless as far as similarity is concerned. This is because, from a statistical point of view, the points become equidistant if another metric is used. Those studies have also shown that the number of bins should be kept as small as possible. If the number of bins become too large, the density of points in the solution space increases and the discrimination is consequently reduced. Not only the discrimination is lost but also the probability to obtain false trues becomes very high. It is possible to reduce this undesirable effect by reducing the number of bins; but then some information is lost and the sampling can become inadequate. Although it is not clear at the moment, those results may indicate that the use of metrics may not be the best way to compare histograms. A histogram can be seen as a distribution. In such a case the metric can be replaced by a hypothesis test that determines if the two distributions are similar within a confidence interval. Clustering could also be a good approach since it does not directly based on metrics.
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Take-over control paradigms in collaborative virtual environments for training

Take-over control paradigms in collaborative virtual environments for training

6 C ONCLUSION In this paper, the concept of Take-Over Control has been formally introduced and defined as a shared interaction control evolving over time such that the control is transferred between several users. The contributions for each user are balanced using weight func- tions (e.g. smooth and sudden) which allow to change the nature of the Take-Over Control. The proposed framework was then ap- plied to an application of maritime navigation in CVET focusing on the main components of the Take-Over Control metaphor: the in- teractive objects, the interactions, the actor’s contributions and the weight functions. The evaluation of the different proposed solutions showed that user’s tend to appreciate increased user awareness both in terms of visual feedback and control (smooth weight function). This use-case showed how the proposed framework can be used to design and evaluate collaborative interactions.
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Creation of Live Virtual Reality Model of Real Environments from Sensor Fusion

Creation of Live Virtual Reality Model of Real Environments from Sensor Fusion

The system can also allow data browsing through the drawing of the excavator or display maintenance reports. All these functions were also represented as part of the excavator scene graph. 8 OBSERVER AND OPERATOR STATIONS The benefit of IIRO for surface mining is that personnel can observe, and in real-time, the status and productivity of equipment, thus providing greater awareness about the ongoing mine activities. The observer station is a prototype version of a display environment in which mine information (payload, machine condition, and other parameters) is shown in the context of the equipment modeled in the virtual environment. An observer can look at the location of a fleet of mobile equipment within a global world model to observe overall mine operations, or zoom in on a specific on-board system, such as an engine. Sound bites and video clips are incorporated to add to reality of the visualization. From the hardware point-of-view the observer station is composed of a large back-projected screen system of 8' x 10' in dimension. The projector is an Electrohome 9500LC producing an image with SXGA resolution at 260 lumens. An Infinite Reality Engine refreshes the stereo images of the virtual environment every 1/10 of a second. Linked to this graphic
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How to avoid simulation sickness in virtual environments during user displacement

How to avoid simulation sickness in virtual environments during user displacement

While the visual transport delay can be efficiently reduced using high frequency frame rate, the visual-vestibular conflict is inherent to VR, when not using motion platforms. In order to study the impact of displacements on simulation sickness, we have tested various driving scenarios in Renault’s 5-sided ultra-high resolution CAVE. First results indicate that low speed displacements with longitudinal and lateral accelerations under a given perception thresholds are well accepted by a large number of users and relatively high values are only accepted by experienced users and induce VR induced symptoms and effects (VRISE) for novice users, with a worst case scenario corresponding to rotational displacements. These results will be used for optimization technics at Arts et Métiers ParisTech for motion sickness reduction in virtual environments for industrial, research, educational or gaming applications.
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