Despite intense and wide-spread research in both virtual environments (VEs) and usability, the exciting new technology of VEs has not yet been closely coupled with the important characteristic of usability -- a necessary coupling if VEs are to reach their full potential. Although numerous methods exist for usability evaluation of interactive computer applications, these methods have well-known limitations, especially for evaluating VEs. Thus, there is a great need to develop usability evaluation methods and criteria specifically for VEs. Our goal is to increase awareness of the need for usability engineering of VEs and to lay a scientific foundation for developing high-impact methods for usability engineering of VEs. The first step in our multi-year research plan has been accomplished, yielding a comprehensive multi-dimensional taxonomy of usability characteristics specifically for VEs. This taxonomy was developed by collecting and synthesizing information from literature, conferences, World Wide Web (WWW) searches, investigative research visits to top VE facilities, and interviews of VE researchers and developers. The taxonomy consists of four main areas of usability issues: Users and User Tasks in VEs, general user and task characteristics and types of tasks in VEs

Virtual environments are envisioned as being systems that will enhance the communication between humans and computers. If virtual systems are to be effective and well received by their users, considerable human-factors research needs to be accomplished. This paper provides an overview of many of these human-factors issues, including human performance efficiency in virtual worlds (which is likely influenced by task characteristics, user characteristics, human sensory and motor physiology, multimodal interaction, and the potential need for new design metaphors); health and safety issues (of which cybersickness and deleterious physiological aftereffects may pose the most concern); and the social impact of the technology. The challenges each of these factors present to the effective design of virtual environments and systematic approaches to the resolution of each of these issues are discussed. 1 Introduction Efforts to apply virtual reality (VR) technology to advance the fields of medicin...

Immersive virtual environment (WE) technology has great promise as a tool for basic experimental research in psychology. NE technology gives participants the experience of being surrounded by the computer-synthesized environment. We begin with a discussion of the various devices needed to im-plement immersive virtual environments, including object manipulation and social interaction. We re-view the benefits and drawbacks associated with virtual environment technology, in comparison with more conventional ways of doing basic experimental research. We then consider a variety of examples of research using IVE technology in the areas of perception, spatial cognition, and social interaction. Human history records a progression of artifacts for representing and recreating aspects of external reality, ranging from language, drawings, and sculpture in earlier times to the more modern artifacts of photographs, movies, television, and audio recordings. Relatively recently, the digital computer and its associated technologies, includ-ing three-dimensional (3-D) graphics, have given rise to increasingly realistic artifacts that blur the distinction be-

Prostate cancer is the second leading cause of cancer death among men (25% of men with prostate cancer will die of the disease). The most common method of detecting this malignancy is digital rectal examination (DRE). Current DRE training requires medical students to examine a large number of patients before attaining adequate experience. We propose to solve this problem using a virtual reality digital rectal examination simulation. The prototype system consists of a PHANToM haptic interface which provides feedback to the trainee's index finger, a motion restricting board and an SGI workstation, which renders the patient 's anatomy in the region of interest. Four types of prostate were modeled using OpenGL and GHOST haptic library-- normal, enlarged with no tumor, incipient malignancy (single tumor), and advanced malignancy (tumor cluster). Results of initial human factors studies are encouraging, while pointing out the need for more realistic physical modeling. 1 Introduction Prosta...

In the area of medical education, there is a strong need for palpation training to address the specific need of detecting subsurface tumors. A virtual reality training simulation was created to address this need. Utilizing the Rutgers Master II force feedback system, the simulation allows the user to perform a patient examination and palpate (touch) the patient’s virtual liver to search for hard regions beneath the surface. When the user’s fingertips pass over a “tumor, ” experimentally determined force/deflection curves are used to give the user the feeling of an object beneath the surface. A graphical user interface was developed to facilitate navigation as well as provide a training quiz. The trainee is asked to identify the location and relative hardness of tumors, and performance is evaluated in terms of positional and diagnosis errors. 1.

We introduce a general method for evaluating and comparing the expected performance of sensing systems for interactive computer graphics. Example applications include head tracking systems for virtual environments, motion capture systems for movies, and even multi-camera 3D vision systems for image-based visual hulls. Our approach is to estimate the asymptotic position and/or orientation uncertainty at many points throughout the desired working volume, and to visualize the results graphically. This global performance estimation can provide both a quantitative assessment of the expected performance, and intuition about the type and arrangement of sources and sensors, in the context of the desired working volume and expected scene dynamics.

The metaphor introduced in this paper describes a more natural, human-like way to interact with objects in virtual environments. The interaction is controlled by motion-based gestures, which are recognized using the method described in [Bimbe98]. In contrast to the application of artificial and unnatural tools, natural input devices (e.g. the human hand) and human-like expression methods (e.g. gestures) can be used to interact with the objects; but on cost of precision. Pre-selection and artificial assistance (like displayed handles, etc.) become unnecessary or might be used in addition. Possible application scenarios are imaginable wherever an exact alternation of the objects is secondary (e.g. presentation, brain-storming, tactical/strategic planning, etc.), or if more precise methods are used in combination. Three problems have to be addressed : First, the definition of natural, human-like gestures; second, the recognition of these gestures; and, finally, the association w...

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.

Virtual Reality (VR), sometimes called Virtual Environments (VE) has drawn much attention in the last few years. Extensive media coverage causes this interest to grow rapidly. Very few people, however, really know what VR is, what its basic principles and its open problems are. In this paper a historical overview of virtual reality is presented, basic terminology and classes of VR systems are listed, followed by applications of this technology in science, work, and entertainment areas. An insightful study of typical VR systems is done. All components of VR application and interrelations between them are thoroughly examined: input devices, output devices and software. Additionally human factors and their implication on the design issues of VE are discussed . Finally, the future of VR is considered in two aspects: technological and social. New research directions, technological frontiers and potential applications are pointed out. The possible positive and negative influence of VR on li...

A method for detecting potential collisions between three-dimensional moving objects is described in this paper. An object-centered, spherical octree representation is defined and implemented for the localisation of potentially colliding features between polyhedral objects. These features are subsequently tested for intersection in order to calculate precisely the actual collision points. Application of the algorithm for the direct manipulation of objects in a virtual scene is considered, to investigate its real-time behaviour. The performance of the algorithm is found to remain linear with respect to the complexity of the colliding objects. 1 Introduction The detection of collision between two arbitrarily moving objects in a three-dimensional computersimulated environment plays an important role in various research fields: a. In the context of dynamic computer animation, where the sequence of object's position has to be dynamically produced by a physical simulation, as the effect of...