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Book•DOI•

Handbook of Virtual Environments: Design, Implementation, and Applications

TL;DR: The Handbook of Virtual Environments: Design, Implementation, and Applications as mentioned in this paper provides a comprehensive set of contributed articles that address the principles required to define system requirements and design, build, evaluate, implement, and manage the effective use of VE applications.
Abstract: A Complete Toolbox of Theories and Techniques The second edition of a bestseller, Handbook of Virtual Environments: Design, Implementation, and Applications presents systematic and extensive coverage of the primary areas of research and development within VE technology. It brings together a comprehensive set of contributed articles that address the principles required to define system requirements and design, build, evaluate, implement, and manage the effective use of VE applications. The contributors provide critical insights and principles associated with their given areas of expertise to provide extensive scope and detail on VE technology and its applications. Whats New in the Second Edition: Updated glossary of terms to promote common language throughout the community New chapters on olfactory perception, avatar control, motion sickness, and display design, as well as a whole host of new application areas Updated information to reflect the tremendous progress made over the last decade in applying VE technology to a growing number of domains This second edition includes nine new, as well as forty-one updated chapters that reflect the progress made in basic and applied research related to the creation, application, and evaluation of virtual environments. Contributions from leading researchers and practitioners from multidisciplinary domains provide a wealth of theoretical and practical information, resulting in a complete toolbox of theories and techniques that you can rely on to develop more captivating and effective virtual worlds. The handbook supplies a valuable resource for advancing VE applications as you take them from the laboratory to the real-world lives of people everywhere.
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Journal Article•DOI•
TL;DR: This display is used to evaluate the influence of focus cues on perceptual distortions, fusion failures, and fatigue and shows that when focus cues are correct or nearly correct, the time required to identify a stereoscopic stimulus is reduced, stereoacuity in a time-limited task is increased, and distortions in perceived depth are reduced.
Abstract: Three-dimensional (3D) displays have become important for many applications including vision research, operation of remote devices, medical imaging, surgical training, scientific visualization, virtual prototyping, and more. In many of these applications, it is important for the graphic image to create a faithful impression of the 3D structure of the portrayed object or scene. Unfortunately, 3D displays often yield distortions in perceived 3D structure compared with the percepts of the real scenes the displays depict. A likely cause of such distortions is the fact that computer displays present images on one surface. Thus, focus cues-accommodation and blur in the retinal image-specify the depth of the display rather than the depths in the depicted scene. Additionally, the uncoupling of vergence and accommodation required by 3D displays frequently reduces one's ability to fuse the binocular stimulus and causes discomfort and fatigue for the viewer. We have developed a novel 3D display that presents focus cues that are correct or nearly correct for the depicted scene. We used this display to evaluate the influence of focus cues on perceptual distortions, fusion failures, and fatigue. We show that when focus cues are correct or nearly correct, (1) the time required to identify a stereoscopic stimulus is reduced, (2) stereoacuity in a time-limited task is increased, (3) distortions in perceived depth are reduced, and (4) viewer fatigue and discomfort are reduced. We discuss the implications of this work for vision research and the design and use of displays.

1,459 citations

Journal Article•DOI•
TL;DR: The current "state of the art" for virtual reality (VR) applications in the field of motor rehabilitation is reviewed and movements learned by people with disabilities in VR transfer to real world equivalent motor tasks in most cases, and in some cases even generalize to other untrained tasks.
Abstract: In this paper, the current "state of the art" for virtual reality (VR) applications in the field of motor rehabilitation is reviewed. The paper begins with a brief overview of available equipment options. Next, a discussion of the scientific rationale for use of VR in motor rehabilitation is provided. Finally, the major portion of the paper describes the various VR systems that have been developed for use with patients, and the results of clinical studies reported to date in the literature. Areas covered include stroke rehabilitation (upper and lower extremity training, spatial and perceptual-motor training), acquired brain injury, Parkinson's disease, orthopedic rehabilitation, balance training, wheelchair mobility and functional activities of daily living training, and the newly developing field of telerehabilitation. Four major findings emerge from these studies: (1) people with disabilities appear capable of motor learning within virtual environments; (2) movements learned by people with disabilities in VR transfer to real world equivalent motor tasks in most cases, and in some cases even generalize to other untrained tasks; (3) in the few studies (n = 5) that have compared motor learning in real versus virtual environments, some advantage for VR training has been found in all cases; and (4) no occurrences of cybersickness in impaired populations have been reported to date in experiments where VR has been used to train motor abilities.

1,094 citations

Journal Article•DOI•
TL;DR: In this paper, the authors present six areas of tourism in which VR may prove particularly valuable: planning and management, marketing, entertainment, education, accessibility, and heritage preservation, and numerous suggestions for future research are presented.

937 citations

Journal Article•DOI•
TL;DR: A literature review on the second research direction, which aims to capture the real 3D motion of the hand, which is a very challenging problem in the context of HCI.

901 citations

Journal Article•DOI•
TL;DR: This paper introduces the educational use of Web-based 3D technologies and highlights in particular VR features, and identifies constructivist learning as the pedagogical engine driving the construction of VRLE and discusses five constructivistlearning approaches.
Abstract: The use of animation and multimedia for learning is now further extended by the provision of entire Virtual Reality Learning Environments (VRLE). This highlights a shift in Web-based learning from a conventional multimedia to a more immersive, interactive, intuitive and exciting VR learning environment. VRLEs simulate the real world through the application of 3D models that initiates interaction, immersion and trigger the imagination of the learner. The question of good pedagogy and use of technology innovations comes into focus once again. Educators attempt to find theoretical guidelines or instructional principles that could assist them in developing and applying a novel VR learning environment intelligently. This paper introduces the educational use of Web-based 3D technologies and highlights in particular VR features. It then identifies constructivist learning as the pedagogical engine driving the construction of VRLE and discusses five constructivist learning approaches. Furthermore, the authors provide two case studies to investigate VRLEs for learning purposes. The authors conclude with formulating some guidelines for the effective use of VRLEs, including discussion of the limitations and implications for the future study of VRLEs.

620 citations

References
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Journal Article•DOI•
TL;DR: In this article, a new theory for discrete motor learning is proposed, based on the notion of the schema and uses a recall memory to produce movement and a recognition memory to evaluate response correctness.
Abstract: A number of closed-loop postulations to explain motor skills learning and performance phenomena have appeared recently, but each of these views suffers from either (a) logical problems in explaining the phenomena or (b) predictions that are not supported by the empirical evidence. After these difficulties are discussed, a new theory for discrete motor learning is proposed that seems capable of explaining the existing findings. The theory is based on the notion of the schema and uses a recall memory to produce movement and a recognition memory to evaluate response correctness. Some of the predictions are mentioned, research techniques and paradigms that can be used to test the predictions are listed, and data in support of the theory are presented.

2,970 citations

Journal Article•DOI•
TL;DR: The investigation of how the CNS learns to control movements in different dynamical conditions, and how this learned behavior is represented, suggests that the elements of the adaptive process represent dynamics of a motor task in terms of the intrinsic coordinate system of the sensors and actuators.
Abstract: We investigated how the CNS learns to control movements in different dynamical conditions, and how this learned behavior is represented. In particular, we considered the task of making reaching movements in the presence of externally imposed forces from a mechanical environment. This environment was a force field produced by a robot manipulandum, and the subjects made reaching movements while holding the end-effector of this manipulandum. Since the force field significantly changed the dynamics of the task, subjects' initial movements in the force field were grossly distorted compared to their movements in free space. However, with practice, hand trajectories in the force field converged to a path very similar to that observed in free space. This indicated that for reaching movements, there was a kinematic plan independent of dynamical conditions. The recovery of performance within the changed mechanical environment is motor adaptation. In order to investigate the mechanism underlying this adaptation, we considered the response to the sudden removal of the field after a training phase. The resulting trajectories, named aftereffects, were approximately mirror images of those that were observed when the subjects were initially exposed to the field. This suggested that the motor controller was gradually composing a model of the force field, a model that the nervous system used to predict and compensate for the forces imposed by the environment. In order to explore the structure of the model, we investigated whether adaptation to a force field, as presented in a small region, led to aftereffects in other regions of the workspace. We found that indeed there were aftereffects in workspace regions where no exposure to the field had taken place; that is, there was transfer beyond the boundary of the training data. This observation rules out the hypothesis that the subject's model of the force field was constructed as a narrow association between visited states and experienced forces; that is, adaptation was not via composition of a look-up table. In contrast, subjects modeled the force field by a combination of computational elements whose output was broadly tuned across the motor state space. These elements formed a model that extrapolated to outside the training region in a coordinate system similar to that of the joints and muscles rather than end-point forces. This geometric property suggests that the elements of the adaptive process represent dynamics of a motor task in terms of the intrinsic coordinate system of the sensors and actuators.

2,505 citations

Journal Article•DOI•
Pietro Morasso1•
TL;DR: Human subjects were instructed to point one hand to different visual targets which were randomly sequenced, using a paradigm which allowed two degrees of freedom, and trajectories of the hand in space were observed.
Abstract: Human subjects were instructed to point one hand to different visual targets which were randomly sequenced, using a paradigm which allowed two degrees of freedom (shoulder, elbow). The time course of the hand trajectory and the joint angular curves were observed. The latter exhibited patterns which change markedly for different movements, whereas the former preserve similar characteristics (in particular, a single peaked tangential velocity curve). The hypothesis is then formulated that the central command for these movements is formulated in terms of trajectories of the hand in space.

1,619 citations

Journal Article•DOI•
TL;DR: Unrestrained human arm trajectories between point targets have been investigated using a three-dimensional tracking apparatus, the Selspot system, and movement regions were discovered in which the hand paths were curved.
Abstract: Unrestrained human arm trajectories between point targets have been investigated using a three-dimensional tracking apparatus, the Selspot system. Movements were executed between different points in a vertical plane under varying conditions of speed and hand-held load. In contrast to past results which emphasized the straightness of hand paths, movement regions were discovered in which the hand paths were curved. All movements, whether curved or straight, showed an invariant tangential velocity profile when normalized for speed and distance. The velocity profile invariance with speed and load is interpreted in terms of simplification of the underlying arm dynamics, extending the results of Hollerbach and Flash (Hollerbach, J. M., and T. Flash (1982) Biol. Cybern. 44: 67-77).

939 citations

Journal Article•DOI•
TL;DR: The results indicate that detailed aspects of movement trajectory are being continuously monitored on the basis of proprioceptive feedback in relation to motor commands, and fail to support current equilibrium point models, both alpha and lambda, of movement control.
Abstract: 1. Forward reaching movements made during body rotation generate tangential Coriolis forces that are proportional to the cross product of the angular velocity of rotation and the linear velocity of...

763 citations