Abstract Several common systems satisfy some but not all of the VR This paper describes the CAVE (CAVE Automatic Virtual Environment) virtual reality/scientific visualization system in detail and demonstrates that projection technology applied to virtual-reality goals achieves a system that matches the quality of workstation screens in terms of resolution, color, and flicker-free stereo. In addition, this format helps reduce the effect of common tracking and system latency errors. The off-axis perspective projection techniques we use are shown to be simple and straightforward. Our techniques for doing multi-screen stereo vision are enumerated, and design barriers, past and current, are described. Advantages and disadvantages of the projection paradigm are discussed, with an analysis of the effect of tracking noise and delay on the user. Successive refinement, a necessary tool for scientific visualization, is developed in the virtual reality context. The use of the CAVE as a one-to-many presentation

Computer users working with large visual documents, such as large layouts, blueprints, or maps perform tasks that require them to simultaneously access overview information while working on details. To avoid the need for zooming, users currently have to choose between using a sufficiently large screen or applying appropriate visualization techniques. Currently available hi-res "wall-size" screens, however, are cost-intensive, spaceintensive, or both. Visualization techniques allow the user to more efficiently use the given screen space, but in exchange they either require the user to switch between multiple views or they introduce distortion. In this paper, we present a novel approach to simultaneously display focus and context information. Focus plus context screens consist of a hi-res display and a larger low-res display. Image content is displayed such that the scaling of the display content is preserved, while its resolution may vary according to which display region it is displayed in. Focus plus context screens are applicable to practically all tasks that currently use overviews or fisheye views, but unlike these visualization techniques, focus plus context screens provide a single, non-distorted view. We present a prototype that seamlessly integrates an LCD with a projection screen and demonstrate four applications that we have adapted so far.

Virtual environments (VEs) are a relatively new type of human-computer interface in which users perceive and act in a three-dimensional world. The designers of such systems cannot rely solely on design guidelines for traditional two-dimensional interfaces, so usability evaluation is crucial for VEs. This paper presents an overview of VE usability evaluation, to organize and critically analyze diverse work from this field. First, we discuss some of the issues that differentiate VE usability evaluation from evaluation of traditional user interfaces such as GUIs. We also present a review of some VE evaluation methods currently in use, and discuss a simple classification space for VE usability evaluation methods. This classification space provides a structured means for comparing evaluation methods according to three key characteristics: involvement of representative users, context of evaluation, and types of results produced. Finally, to illustrate these concepts, we compare two existing evaluation approaches: testbed evaluation [Bowman, Johnson, & Hodges, 1999], and sequential evaluation [Gabbard, Hix, & Swan, 1999]. 1 Introduction and

The cumbersome nature of wired interfaces often limits the range of application of virtual environments. In this paper we discuss the design and implementation of a novel system, called ALIVE, which allows unencumbered full-body interaction between a human participant and a rich graphical world inhabited by autonomous agents. Based on results obtained with thousands of users, the paper argues that this kind of system can provide more complex and very different experiences than traditional virtual reality systems. The ALIVE system significantly broadens the range of potential applications of virtual reality systems; in particular, the paper discusses novel applications in the area of training and teaching, entertainment, and digital assistants or interface agents. We overview the methods used in the implementation of the exiting ALIVE systems.

High-speed wide area networks are expected to enable innovative applications that integrate geographically distributed, high-performance computing, database, graphics, and networking resources. However, there is as yet little understanding of the higher-level services required to support these applications, or of the techniques required to implement these services in a scalable, secure manner. We report on a large-scale prototyping effort that has yielded some insights into these issues. Building on the hardware base provided by the I-WAY, a national-scale Asynchronous Transfer Mode (ATM) network, we developed an integrated management and application programming system, called I-Soft. This system was deployed at most of the 17 I-WAY sites and used by many of the 60 applications demonstrated on the I-WAY network. In this article, we describe the I-Soft design and report on lessons learned from application experiments. 1

The Message Passing Interface (MPI) can be used as a portable, high-performance programming model for wide-area computing systems. The wide-area environmentintroduces challenging problems for the MPI implementor, due to the heterogeneity of both the underlying physical infrastructure and the software environment at different sites. In this article, we describe an MPI implementation that incorporates solutions to these problems. This implementation has been constructed by extending the Argonne MPICH implementation of MPI to use communication services provided by the Nexus communication library and authentication, resource allocation, process creation/management, and information services provided by the I-Soft system (initially) and the Globus metacomputing toolkit (work in progress). Nexus provides multimethod communication mechanisms that allowmultiple communication methods to be used in a single computation with a uniform interface; I-Soft and Globus provided standard authent...

This paper presents a gameplay experience model, assesses its potential as a tool for research and presents some directions for future work. The presented model was born from observations among game-playing children and their non-player parents, which directed us to have a closer look at the complex nature of gameplay experience. Our research led into a heuristic gameplay experience model that identifies some of the key components and processes that are relevant in the experience of gameplay, with a particular focus on immersion. The model includes three components: sensory, challenge-based and imaginative immersion (SCI-model). The classification was assessed with self-evaluation questionnaires filled in by informants who played different popular games. It was found that the gameplay experiences related to these games did indeed differ as expected in terms of the identified three immersion components.

The MagicBook is a Mixed Reality interface that uses a real book to seamlessly transport users between Reality and Virtuality. A vision-based tracking method is used to overlay virtual models on real book pages, creating an Augmented Reality (AR) scene. When users see an AR scene they are interested in they can fly inside it and experience it as an immersive Virtual Reality (VR). The interface also supports multi-scale collaboration, allowing multiple users to experience the same virtual en vironment either from an egocentric or an exocentric perspective. In this paper we describe the MagicBook prototype, potential applications and user response.

In the Shared Space project, we explore, innovate, design and evaluate future computing environments that will radically enhance interaction between human and computers as well as interaction between humans mediated by computers. In particular, we investigate how augmented reality enhanced by physical and spatial 3D user interfaces can be used to develop effective face-toface collaborative computing environments. How will we interact in such collaborative spaces? How will we interact with each other? What new applications can be developed using this technology? These are the questions that we are trying to answer in research on Shared Space. This paper provides a short overview of Shared Space, its directions, technologies and applications.

A new generation of specialized scientific instruments called synchrotron light sources allow the imaging of materials at very fine scales. However, in contrast to a traditional microscope, interactive use has not previously been possible because of the large amounts of data generated and the considerable computation required translating this data into a useful image. We describe a new software architecture that uses high-speed networks and supercomputers to enable quasi-real-time and hence interactive analysis of synchrotron light source data. This architecture uses technologies provided by the Globus "computational grid" toolkit to allow dynamic creation of a reconstruction pipeline that transfers data from a synchrotron source beamline to a preprocessing station, next to a parallel reconstruction system, and then to multiple visualization stations. Collaborative analysis tools allow multiple users to control data visualization. As a result, local and remote scientists can...