Spatial navigation in large-scale virtual environments: Gender differences in survey tasks

Most of the studies on gender differences in spatial abilities have focused on traditional paper and pencil cognitive tests, while these differences have been less investigated in navigational tasks carried out in complex virtual environments (VEs). The aim of the present study has been to evaluate gender differences in route and survey knowledge by means of specific tasks (route-learning, pointing, landmark-placing) carried out in two separate VEs. In addition the male and female participants were subjected to a battery of spatial abilities tests and specific self-report questionnaires. The results showed a significant difference favouring males in the survey tasks, as well as in the spatial abilities tests; on the contrary, no gender differences were found in the route task. Moreover, a different pattern of correlations among the measures were found in the male and female sub-groups.     

Real-time path planning in dynamic virtual environments using multiagent navigation graphs

We present a novel approach for efficient path planning and navigation of multiple virtual agents in complex dynamic scenes. We introduce a new data structure, Multi-agent Navigation Graph (MaNG), which is constructed using first- and second-order Voronoi diagrams. The MaNG is used to perform route planning and proximity computations for each agent in real time. Moreover, we use the path information and proximity relationships for local dynamics computation of each agent by extending a social force model [Helbing05]. We compute the MaNG using graphics hardware and present culling techniques to accelerate the computation. We also address undersampling issues and present techniques to improve the accuracy of our algorithm. Our algorithm is used for real-time multi-agent planning in pursuit-evasion, terrain exploration and crowd simulation scenarios consisting of hundreds of moving agents, each with a distinct goal.     

Effects of head-slaved navigation and the use of teleports on spatial orientation in virtual environments

The type of navigation interface in a virtual environment (VE)--head slaved or indirect--determines whether or not proprioceptive feedback stimuli are present during movement. In addition, teleports can be used, which do not provide continuous movement but, rather, discontinuously displace the viewpoint over large distances. A two-part experiment was performed. The first part investigated whether head-slaved navigation provides an advantage for spatial learning in a VE. The second part investigated the role of anticipation when using teleports. The results showed that head-slaved navigation has an advantage over indirect navigation for the acquisition of spatial knowledge in a VE. Anticipating the destination of the teleport prevented disorientation after the displacement to a great extent but not completely. The time that was needed for anticipation increased if the teleport involved a rotation of the viewing direction. This research shows the potential added value of using a head-slaved navigation interface--for example, when using VE for training purposes--and provides practical guidelines for the use of teleports in VE applications.     

Planning optimal paths: A simple assessment of survey spatial knowledge in virtual environments

In spatial cognition studies several cognitive factors were analysed in order to identify the aspect that could constitute the basis for the capacity of organising spatial knowledge into survey maps.     

Going to town: Visualized perspectives and navigation through virtual environments

Two experiments examined how spatial learning perspectives support navigation through virtual urban environments. Participants briefly learned the overall layout of a virtual desktop environment, and then were taken on a simulated journey ending at a starting location within the environment. In Experiment 1, during the journey participants watched simulated video feeds either from the front of the vehicle (route perspective), above the vehicle (survey perspective), both feeds simultaneously, or no video at all. Participants then navigated between ten successive landmarks, and we measured indices of spatial and temporal efficiency, and heading error. Results indicated that the route perspective supported a restricted range of local navigation whereas the survey perspective better supported far-space navigation. Experiment 2 demonstrated that the survey perspective also better supports navigation around unexpected detours. Results are discussed with regard to theories of spatial memory and the design of computer-supported spatial visualization technologies.     

VU-flow: a visualization tool for analyzing navigation in virtual environments

This paper presents a tool for the visual analysis of navigation patterns of moving entities, such as users, virtual characters or vehicles in 3D virtual environments (VEs). The tool, called VU-Flow, provides a set of interactive visualizations that highlight interesting navigation behaviors of single or groups of moving entities that were the VE together or separately. The visualizations help to improve the design of VEs and to study the navigation behavior of users, e.g., during controlled experiments. Besides VEs, the proposed techniques could also be applied to visualize real-world data recorded by positioning systems, allowing one to employ VU-Flow in domains such as urban planning, transportation, and emergency response     

RUN: rational ubiquitous navigation,a model for automated navigation and searching in virtual environments

Virtual Reality - By now, the realm of virtual reality is abuzz with high-quality visuals, enough to simulate a real-world scene. The use of intelligence in virtual reality systems, however, is a...     

Human interactions and personal space in collaborative virtual environments

As humans start to spend more time in collaborative virtual environments (CVEs) it becomes important to study their interactions in such environments. One aspect of such interactions is personal space. To begin to address this, we have conducted empirical investigations in a non immersive virtual environment: an experiment to investigate the influence on personal space of avatar gender, and an observational study to further explore the existence of personal space. Experimental results give some evidence to suggest that avatar gender has an influence on personal space although the participants did not register high personal space invasion anxiety, contrary to what one might expect from personal space invasion in the physical world. The observational study suggests that personal space does exist in CVEs, as the users tend to maintain, in a similar way to the physical world, a distance when they are interacting with each other. Our studies provide an improved understanding of personal space in CVEs and the results can be used to further enhance the usability of these environments.     

Redirecting walking and driving for natural navigation in immersive virtual environments

Walking is the most natural form of locomotion for humans, and real walking interfaces have demonstrated their benefits for several navigation tasks. With recently proposed redirection techniques it becomes possible to overcome space limitations as imposed by tracking sensors or laboratory setups, and, theoretically, it is now possible to walk through arbitrarily large virtual environments. However, walking as sole locomotion technique has drawbacks, in particular, for long distances, such that even in the real world we tend to support walking with passive or active transportation for longer-distance travel. In this article we show that concepts from the field of redirected walking can be applied to movements with transportation devices. We conducted psychophysical experiments to determine perceptual detection thresholds for redirected driving, and set these in relation to results from redirected walking. We show that redirected walking-and-driving approaches can easily be realized in immersive virtual reality laboratories, e. g., with electric wheelchairs, and show that such systems can combine advantages of real walking in confined spaces with benefits of using vehicle-based self-motion for longer-distance travel.     

Computer based assessment: Gender differences in perceptions and acceptance

This study identifies the constructs that affect male and female students’ behavioural intention to use a computer based assessment (CBA). It extends the Computer Based Assessment Acceptance Model (CBAAM) (Terzis & Economides, 2011) by taking into consideration the genders. An appropriate survey questionnaire was completed by 56 male and 117 female students. Results indicate that both genders are more likely to use the CBA if it is playful and its content is clear and relative to the course. Men are also motivated by their perceptions regarding how much useful the CBA is. Also, their attitude towards the CBA is influenced by their social environment. On the other side, women are more likely to use the CBA if it is easy to use and stimulates their efforts for better final exam preparation. The CBAAM incorporating genders explains approximately 50% of the variance of behavioural intention for each gender. These findings are useful for researchers and practitioners in order to understand better the different constructs that affect each gender regarding the acceptance of a CBA system.     

Efficient grid-based spatial representations for robot navigation in dynamic environments

In robotics, grid maps are often used for solving tasks like collision checking, path planning, and localization. Many approaches to these problems use Euclidean distance maps (DMs), generalized Voronoi diagrams (GVDs), or configuration space (c-space) maps. A key challenge for their application in dynamic environments is the efficient update after potential changes due to moving obstacles or when mapping a previously unknown area. To this end, this paper presents novel algorithms that perform incremental updates that only visit cells affected by changes. Furthermore, we propose incremental update algorithms for DMs and GVDs in the configuration space of non-circular robots. These approaches can be used to implement highly efficient collision checking and holonomic path planning for these platforms. Our c-space representations benefit from parallelization on multi-core CPUs and can also be integrated with other state-of-the-art path planners such as rapidly-exploring random trees.In various experiments using real-world data we show that our update strategies for DMs and GVDs require substantially less cell visits and computation time compared to previous approaches. Furthermore, we demonstrate that our GVD algorithm deals better with non-convex structures, such as indoor areas. All our algorithms consider actual Euclidean distances rather than grid steps and are easy to implement. An open source implementation is available online.     

Navigation in 3D virtual environments: Effects of user experience and location-pointing navigation aids

In this paper, we describe the results of an experimental study whose objective was twofold: (1) comparing three navigation aids that help users perform wayfinding tasks in desktop virtual environments (VEs) by pointing out the location of objects or places; (2) evaluating the effects of user experience with 3D desktop VEs on their effectiveness with the considered navigation aids. In particular, we compared navigation performance (in terms of total time to complete an informed search task) of 48 users divided into two groups: subjects in one group had experience in navigating 3D VEs while subjects in the other group did not. The experiment comprised four conditions that differed for the navigation aid that was employed. The first and the second condition, respectively, exploited 3D and 2D arrows to point towards objects that users had to reach; in the third condition, a radar metaphor was employed to show the location of objects in the VE; the fourth condition was a control condition with no location-pointing navigation aid available. The search task was performed both in a VE representing an outdoor geographic area and in an abstract VE that did not resemble any familiar environment. For each VE, users were also asked to order the four conditions according to their preference. Results show that the navigation aid based on 3D arrows outperformed (both in terms of user performance and user preference) the others, except in the case when it was used by experienced users in the geographic VE. In that case, it was as effective as the others. Finally, in the geographic VE, experienced users took significantly less time than inexperienced users to perform the informed search, while in the abstract VE the difference was significant only in the control and the radar conditions. From a more general perspective, our study highlights the need to take into specific consideration user experience in navigating VEs when designing navigation aids and evaluating their effectiveness.     

The WALKABOUT: Using virtual environments to assess large-scale spatial abilities

Computer-simulated virtual environments (VEs) offer promise for assessing people's spatial abilities in large real-world environments. This paper introduces the WALKABOUT, a VE-based test that simulates navigation through large spaces. Participants' ability to form an accurate mental representation of a familiar large-scale environment correlated nearly as highly with their performance on the WALKABOUT as it did with their self-reported sense of direction. Performance on two subscales of the test further indicated that the ability to account for changing egocentric relationships as a result of self-movement and the ability to recognize a novel perspective on an environment are both significantly related to spatial ability at the environmental scale.     

Training in peacekeeping operations using virtual environments

Proper training of military personnel, at all levels, has never been more crucial. In this article, we describe the application of virtual environment technology to a novel and complex task-the military checkpoint. In the process, we also address differences between an immersive virtual environment training system and a destop version.     

Cooperative multi-robot belief space planning for autonomous navigation in unknown environments

We investigate the problem of cooperative multi-robot planning in unknown environments, which is important in numerous applications in robotics. The research community has been actively developing belief space planning approaches that account for the different sources of uncertainty within planning, recently also considering uncertainty in the environment observed by planning time. We further advance the state of the art by reasoning about future observations of environments that are unknown at planning time. The key idea is to incorporate within the belief indirect multi-robot constraints that correspond to these future observations. Such a formulation facilitates a framework for active collaborative state estimation while operating in unknown environments. In particular, it can be used to identify best robot actions or trajectories among given candidates generated by existing motion planning approaches, or to refine nominal trajectories into locally optimal paths using direct trajectory optimization techniques. We demonstrate our approach in a multi-robot autonomous navigation scenario and consider its applicability for autonomous navigation in unknown obstacle-free and obstacle-populated environments. Results indicate that modeling future multi-robot interaction within the belief allows to determine robot actions (paths) that yield significantly improved estimation accuracy.     

Supporting cognitive processing with spatial information presentations in virtual environments

While it has been suggested that immersive virtual environments could provide benefits for educational applications, few studies have formally evaluated how the enhanced perceptual displays of such systems might improve learning. Using simplified memorization and problem-solving tasks as representative approximations of more advanced types of learning, we are investigating the effects of providing supplemental spatial information on the performance of learning-based activities within virtual environments. We performed two experiments to investigate whether users can take advantage of a spatial information presentation to improve performance on cognitive processing activities. In both experiments, information was presented either directly in front of the participant, at a single location, or wrapped around the participant along the walls of a surround display. In our first experiment, we measured memory scores and analyzed participant strategies for a memorization and recall task. In addition to comparing spatial and non-spatial presentations, we also varied field of view and background imagery. The results showed that the spatial presentation caused significantly better memory scores. Additionally, a significant interaction between background landmarks and presentation style showed that participants used more visualization strategies during the memorization task when background landmarks were shown with spatial presentations. To investigate whether the advantages of spatial information presentation extend beyond memorization to higher level cognitive activities, our second experiment employed a puzzle-like task that required critical thinking using the presented information. Focusing only on the effects of spatial presentations, this experiment measured task performance and mental workload. The results indicate that no performance improvements or mental workload reductions were gained from the spatial presentation method compared with a non-spatial layout for our problem-solving task. The results of these two experiments suggest that supplemental spatial information can affect mental strategies and support performance improvements for cognitive processing and learning-based activities. However, the effectiveness of spatial presentations is dependent on the nature of the task and a meaningful use of space and may require practice with spatial strategies.     

Rendering localized spatial audio in a virtual auditory space

High-quality virtual audio scene rendering is required for emerging virtual and augmented reality applications, perceptual user interfaces, and sonification of data. We describe algorithms for creation of virtual auditory spaces by rendering cues that arise from anatomical scattering, environmental scattering, and dynamical effects. We use a novel way of personalizing the head related transfer functions (HRTFs) from a database, based on anatomical measurements. Details of algorithms for HRTF interpolation, room impulse response creation, HRTF selection from a database, and audio scene presentation are presented. Our system runs in real time on an office PC without specialized DSP hardware.     

Intelligent Cruise-Control Navigation: A new navigation/travel method for use in virtual environments

An important feature of virtual reality is the facility for the user to move around a virtual environment in a natural and easily controlled manner. Navigation, also called locomotion, travel or motion, involves changing the perspective of the user in the virtual environment (VE). It allows the user to move in the VE as well as reorient themselves to look at the world differently. Natural locomotion methods are able to contribute to a sense of presence and reality. The illusion of presence can be lost through unnatural experiences during travel in the VE. This can be caused by poor interactive metaphors or by experiences which do not agree with the user's everyday understanding of the real world. This paper focuses on the navigation method in the VE, one of the major interfaces for the interactivity between human and VE in virtual reality circumstances and worlds. It proposes a new navigation method. Intelligent Cruise-Control Navigation (ICCN), which provides a natural and user-centred approach to navigation in the VE and can improve the user's sense of reality and presence. ICCN is composed of three major phases: Constant Velocity Navigation, Collision Detection and Avoidance, and Path Adjustment. The ICCN can reduce the user's fatigue and improve the user's presence in the VE. The small experimental study reported in this paper suggests that the ICCN will be a natural, straightforward, and useful navigation interface in VE.