Abstract: This paper describes an experiment to assess the influence of immersion on performance in immersive virtual environments. The task involved Tri-Dimensional Chess, and required subjects to reproduce on a real chess board the state of board learned from a sequence of moves witnessed in a virtual environment. Twenty four subjects were allocated to a factorial design consisting of two levels of immersion (exocentric screen based, and egocentric HMD based), and two kinds of environment (plain and realistic). The results suggest that egocentric subjects performed better than exocentric, and those in the more realistic environment performed better than those in the less realistic environment. Previous knowledge of chess, and amount of virtual practice were also significant, and may be considered as control variables to equalise these factors amongst the subjects. Other things being equal, males remembered the moves better than females, although female performance improved with higher spatial ability test score. The paper also attempts to clarify the relationship between immersion, presence and performance, and locates the experiment within such a theoretical framework.

Abstract: This paper describes the synchronization and communication primitives of the Cray T3E multiprocessor, a shared memory system scalable to 2048 processors. We discuss what we have learned from the T3D project (the predecessor to the T3E) and the rationale behind changes made for the T3E. We include performance measurements for various aspects of communication and synchronization.The T3E augments the memory interface of the DEC 21164 microprocessor with a large set of explicitly-managed, external registers (E-registers). E-registers are used as the source or target for all remote communication. They provide a highly pipelined interface to global memory that allows dozens of requests per processor to be outstanding. Through E-registers, the T3E provides a rich set of atomic memory operations and a flexible, user-level messaging facility. The T3E also provides a set of virtual hardware barrier/eureka networks that can be arbitrarily embedded into the 3D torus interconnect.

Abstract: An object-oriented, multi-media architecture provides for real-time processing of an incoming stream of pseudo-language byte codes compiled from an object-oriented source program The architecture includes a plurality of processors arranged for parallel processing At least some of the processors are especially adapted or optimized for execution of multi-media methods such as video decompression, inverse discrete cosine transformation, motion estimation and the like The architecture further includes a virtual machine computer program that reconstructs objects and threads from the byte code stream, and routes each of them to the appropriate hardware resource for parallel processing This architecture extends the object-oriented paradigm through the operating system and execution hardware of a client machine to provide the advantages of dedicated/parallel processors while preserving portability of the pseudo-language environment

Abstract: Virtual reality (VR) has invaded the public's awareness through a series of media articles that have promoted it as a new and exciting form of computer interaction. We discuss the extent to which VR may be a useful tool in visualization and attempt to disambiguate the use of VR as a general descriptor for any three-dimensional computer presentation. The argument is presented that, to warrant the use of the term virtual environment (VE), the display should satisfy criteria that arise from the nature of human spatial perception. It directly follows, therefore, that perceptual criteria are the foundations of an effective VE display. We address the task of making a VE system easy to navigate, traverse and engage, by examining the ways in which three-dimensional perception and perception of motion may be supported, and consider the potential conflict that may arise between depth cues. We propose that the design of VE systems must centre on the perceptual-motor capabilities of the user, in the context of the task to be undertaken, and establish what is essential, desirable and optimal in order to maximize the task gains, while minimizing the learning required to operate within three-dimensional interactive displays.

Abstract: Creators of multiuser virtual environments naturally desire to make them large in spatial extent, large in numbers of objects, and large in numbers of users interacting with the environment. However, doing so creates several problems: efficiently managing the flow of large amounts of data between large numbers of users, representing precise position and velocity information about objects arrayed across a large volume of space, and allowing designers to create parts of a virtual environment separately and combine them together later. The concept of locales is based on the idea that even in a very large virtual world, most of what a single user can observe at a given moment is nevertheless local in nature. You would expect a large virtual world to be large primarily because, like a city, it combines a large number of relatively small, localized activities not because it contains very large individual activities. Locales divide a virtual world into chunks that can be processed separately. This division is purely an implementation issue-it is not apparent to the user. A user sees several locales at once-generally the locale containing the user's point of view and those neighboring it. The user does not see any seams between the locales nor any abrupt changes as the point of view moves from one locale to another, thereby changing the neighborhood set.

Abstract: A virtual network consists of many distributed virtual computers interconnected over a communication network of individual links, such as optical fibers or electrical conductors, for example. Each distributed virtual computer has at least two ports connected over respective links to other respective distributed virtual computers on the network. Each distributed virtual computer is connected to or resident within its own host, each host typically being a conventional computer such as a personal computer or a work station, for example, although at least one of the hosts may itself be another virtual computer. Each distributed virtual computer has reconfigurable logic elements such as an FPGA or an array of FPGAs.

Abstract: There is a natural desire to make multi-user virtual environments large in spatial extent, in numbers of objects, and in numbers of users interacting with the environment. However, doing this brings up several problems: efficiently managing the flow of large amounts of data between large numbers of users, representing precise position and velocity information about objects that are arrayed across a large volume of space, and allowing designers to create parts of a virtual environment separately and combine them together later. Locales are an efficient method for solving these problems by breaking up a virtual world into compact chunks that can be described and communicated independently. In addition, locales can be used to support a number of special effects that allow virtual worlds to easily transcend reality. While having many benefits, locales introduce an additional problem: finding something when you do not know what locale it is in. This is solved by the companion concept of beacons, which makes it possible to find something no matter where it is.

Abstract: : This report reviews current interface technology for use in virtual environments. Visual, tracking, auditory, primary user input (including, for example, glove, body suit, exoskeleton, track ball, and 3-D mouse inputs), tactile, kinesthetic, full-body motion, and olfactory interface technologies are covered. In each case, the relevant human capabilities are discussed, followed by descriptions of some available commercial products and ongoing research and development efforts. This information is used as the basis for predicting how virtual environment interfaces are likely to change in the next five years.

Abstract: Investigates the trade-off of different network topologies and messaging protocols for multi-user virtual environment systems. We present message distribution techniques appropriate for constructing scalable multi-user systems for a variety of network characteristics. Hierarchical system designs utilizing servers that manage message distribution for entities in separate regions of a virtual environment are described that scale to arbitrary numbers of simultaneous users. Experimental results show that the rate of messages processed by server workstations in this system design are less than using previously described approaches.

Abstract: The present invention facilitates viewing, organizing, and optimizing Internet sites. A multi-dimensional virtual environment includes one or more respective virtual sites for each Internet site. Users are given the ability to explore the virtual environment and access Internet site data and services via respective virtual site(s). Transfer of data related to an Internet and virtual site includes assigning a transfer priority to each virtual site based on the user's location within the virtual environment, and transferring data based on the assigned priority. Users are provided with the ability to lease portions of the virtual environment, to create and modify the appearance and functionality of virtual sites on leased portions, to assign Internet site data and services to virtual sites, and to relocate virtual sites within the virtual environment.

Abstract: Currently, the hardware to produce virtual environments does not include olfactory displays, in spite of the fact that a wealth of sensory information is available from the olfactory sense. This paper reviews the physiological and psychological aspects of olfaction and discusses the use of olfactory displays for virtual environments. Further, it outlines the information that will be needed by the virtual environment research community to integrate olfactory stimuli into virtual environments.

Abstract: Virtual Actors now play an important role in computer-generated films, Virtual Environments, Telecooperative work, and multimedia. In order to make these actors realistic, it is essential to represent their body shape during the motion. In this paper we present different methods for representing realistic deformations for virtual humans with various characteristics: sex, age, height, weight. Our methods based on a combination of metaballs and splines could be applied to frame-by-frame computer generated-films and Virtual Environments. Several examples are presented: autonomous actors, animation based on flock of birds, networked Virtual Environments.

Abstract: Putting the reality into virtual environments requires much more than outstanding 3D computer graphics and effective human computer interaction. To be "real", elements of the virtual environment must not only look realistic and provide natural interaction, they must move correctly, behave believably, and approximate the complexity of the real world. Individual computer systems cannot provide the necessary degree of complexity, scale, and fidelity, and probably never will. Achieving a representation of an environment that looks accurate and is accurate in its details requires multiple computer systems and distributed virtual environment (DVE) technology. The article provides an introduction to the major components of DVEs and the issues related to assembling large scale DVEs. DVE technology permits real time human interaction with complex environments based on 3D graphical descriptions that interact and move using models of real world physical constraints.

Abstract: This paper evaluates the design and implementation of Omniware: a safe, efficient, and language-independent system for executing mobile program modules. Previous approaches to implementing mobile code rely on either language semantics or abstract machine interpretation to enforce safety. In the former case, the mobile code system sacrifices universality to gain safety by dictating a particular source language or type system. In the latter case, the mobile code system sacrifices performance to gain safety through abstract machine interpretation.Omniware uses software fault isolation, a technology developed to provide safe extension code for databases and operating systems, to achieve a unique combination of language-independence and excellent performance. Software fault isolation uses only the semantics of the underlying processor to determine whether a mobile code module can corrupt its execution environment. This separation of programming language implementation from program module safety enables our mobile code system to use a radically simplified virtual machine as its basis for portability. We measured the performance of Omniware using a suite of four SPEC92 programs on the Pentium, PowerPC, Mips, and Sparc processor architectures. Including the overhead for enforcing safety on all four processors, OmniVM executed the benchmark programs within 21% as fast as the optimized, unsafe code produced by the vendor-supplied compiler.

Abstract: The invention is a real-time programming method (RTPM) for use in writing application programs to be executed by virtual machines and a method practiced by a real-time virtual machine (RTVM) while executing an application program written in accordance with a real-time programming method. The invention also includes a method for translating an RTPM programming language into a second programming language, the RTPM programming language being an extended version of the second programming language. The RTPM programming language includes real-time code expressions for specifying real-time execution requirements. The method of translating the real-time code expressions is such that the execution of a second-language translation of a RTPM-language application program complies with the real-time execution requirements on a best-effort basis. The RTPM utilizes a configure method and a negotiate method. The invocation of the configure method in an application program results in the quantification of the needs for one or more resources during execution of the application program by a virtual machine. The invocation of the negotiate method in an application program causes a negotiation to occur between the application program and the virtual machine concerning the allocation of one or more resources to the application program, the resources including CPU time, total memory, and memory allocation rate.

Abstract: The Batrun distributed processing system locates idle workstations in a cluster and uses them as one virtual computer for batch processing. To guarantee that local users have top priority for their machines, Batrun preempts the batch jobs and migrates them to other machines.

Abstract: A system and method for implementing one or more specific purpose rule-based n-bit virtual processing machines. Specific purposes include, but are not limited to, encryption, compression, and arbitrary precision arithmetic. Each virtual machine consists of a command processor, a rule-base, and an interface between the command processor and the rule-base. Each of the elements of a specific purpose rule-based n-bit virtual machine--the command processor, the rule-base, and the rule-base interface--is preferably implemented as software. In the preferred embodiment, the system uses a stored rule-base as its instruction set and provides for input and output in the form of variable length bit strings of length n where n is any number greater than zero. Each of the rules within the rule-base performs one or more binary string operations against one or more variable length n-bit strings. The function of the rule-base is to provide a set of application specific rules that allows the machine to perform a particular task such as encryption, data compression, or arbitrary precision arithmetic. The system includes a method for providing a software interface to the rule-base. This interface may be a separate program or may be contained within the command processor. The command processor receives input in the form of one or more n-bit data types, performs rule-based operations on the data, and returns output in the form of one or more n-bit data types. Specific system and methods for performing data encryption, data compression, and arbitrary precision arithmetic using the invention are described.

Abstract: In a fault recovery method for a multi-processor system including a main storage and a plurality of virtual machines which are assigned to a plurality of processors under control of a host operating system and a plurality of guest operating systems and which operate on the processors associated therewith, a fault occurring in one of the processors is detected to recover functions of the system. The method includes the steps of setting recovery attributes for failure to each of the virtual machines, assigning a plurality of virtual machines to a plurality of processors and operating the virtual machines on the processors respectively associated therewith, storing, at detection of occurrence of a fault in one of the processors, data and status information of virtual machines assigned to the processor and status information of the processor respectively in a virtual machine save area and a real machine save area of the main storage, storing fault information of the processor in the main storage by a fault recovery circuit having received a report of the fault, restarting an interrupted process and causing an interruption according to the status information of the virtual machines and the status information and fault information of the processor which are obtained from the main storage, and retrieving, when the interruption is received, one of the virtual machines assigned to the processor according to the processor status information in the real machine save area and then assigning the plural virtual machines to the plural processors for operation thereof according to the recovery attributes for failure set to the retrieved virtual machine.

Abstract: One long-term goal at the University of Illinois at Chicago's Electronic Visualization Laboratory is to create a persistent virtual environment enabling transcontinental collaboration over high-speed and high-bandwidth networks connected to heterogeneous supercomputing resources and large data stores Our focus is on researching techniques required to support general collaboration in persistent virtual environments These techniques include the representation of virtual co-presence, video and audio teleconferencing, virtual reality (VR) interfaces, and database technology for sustaining persistence in virtual worlds These techniques are used in a collaborative design laboratory called Calvin (Collaborative Architecture Via Immersive Navigation) Calvin was designed to run in the Cave Automatic Virtual Environment (CAVE)

Abstract: Although original applications in virtual reality (VR) for medicine pertained to the planning of surgeries, efforts have now shifted to the use of data fusion, i.e. to fuse virtual patients onto real patients as a navigational aid in surgery. Eventually, medical care with multiple professionals will be provided in a shared virtual environment that incorporates shared decision making for an actual surgical intervention or a rehearsal. The major applications of virtual reality in surgery can be divided into three areas: virtual humans for training, the fusion of virtual humans with real humans for performing surgery, and virtual telemedicine shared decision environments for training of multiple players. The applications pertaining to the realisation of virtual reality in medicine can be categorised into two areas: generic models and patient specific models.

Abstract: A system and method for a downloadable just-in-time middleware called VEM that provides access to network services, including system services such as printing and local storage, to applications that run on Network Computers. The VEM configures the default client services and stores information about these services. When an application executing on the Network Computer wishes to use one of the services, it communicates with its local VEM. The VEM returns a handle to the appropriate service to complete the service request.

Abstract: Discusses the emergent World Wide Web-based distributed environments for high-performance computing and communications (HPCC) on the National Information Infrastructure (NII) with the focus on Java as an enabling technology. We start with a review of the past, present and near-term future of the "Java phenomenon", exposed in the background of some related previous approaches towards a distributed interpretative virtual machine architecture. Next, we discuss the anticipated role of Java in building distributed Web-based computing environments. We outline an evolutionary path from the current Web technology "soup" towards "all-Java" systems and we illustrate this process in terms of the Northeast Parallel Architectures Center (NPAC) Web technology prototypes (WebVM, WebFlow, Bridge-based Collaboratory) and selected applications (CareWeb, 3D Visible Human).

Abstract: This paper describes a system that combines a textual virtual environment (MOO -MUD Object Oriented) and a WWW browser. The MOO provides a text-only but information-rich spatial user interface in which objects and locations can be associated with pointers to WWW pages. When using a specialized MOO client, navigation in the MOO causes the corresponding Web pages to be loaded. The overall effect is the possibility to navigate the Web using spatial navigational metaphors. Textual virtual environments support the creation of diverse navigation tools and metaphors. The Juggler system we describe can thus serve as an experimental tool to explore diverse navigational metaphors for the WWW. The system uses references to Web pages which can be arranged in any possible way and allows users to overlay a new secondary structure on existing Web structures, even using Web pages not on one's own Web server. Textual virtual environments further support almost real time communication and interaction between several users. Because of the extensive interaction possibilities, the Juggler system can be used to discuss material on the Web, conduct guided tours through the Web or give presentations using material available on the Web.

Abstract: Annotation is a key operation for developing understanding of complex data or extended spaces. We have developed a flexible set of annotation tools that can be placed in a variety of applications. These tools offer a full set of capabilities for inserting, iconizing, playing back and organizing annotations in a virtual space. They also have an intuitive and easy-to-use interface for employing these capabilities while immersed in the virtual environment. We illustrate the annotation system with two diverse examples: a general data visualization/analysis application and an architectural walkthrough.

Abstract: A tactile interface system which provides a method for entering user position into a virtual reality and providing tactile feedback from that virtual reality. This system will allow for the representation of the user limb position and enable the user to feel interactions with objects represented in the virtual reality. The system also provides for the recording of tactile information to accompany audio and visual recordings.

Abstract: This survey of heterogeneous computing concepts and systems is based on the recently proposed by the authors "EM/sup 3/ " (Execution Modes/Machine Models) taxonomy of computer systems in general. The taxonomy is based on two criteria: the number of execution modes supported by the system and the number of machine models present in the system. Since these two criteria are orthogonal, four classes exist: Single Execution mode/Single machine Model (SESM), Single Execution modes/Multiple machine Models (SEMM), Multiple Execution modes/Single machine Model (MESM), and Multiple Execution modes/Multiple machine Models (MEMM). In Section II, heterogeneous computing concepts are viewed through three phases of the compilation and execution of any heterogeneous application: parallelism detection, parallelism characterization and resource allocation. Parallelism detection phase discovers fine-grain parallelism inside every task. This phase is not an exclusive feature of heterogeneous computing, so it will not be dealt with in greater detail. The assignment of parallelism characterization phase is to estimate the behavior of each task in the application on every architecture in the heterogeneous system. In the parallelism characterization domain, one original taxonomy is given. This taxonomy contains scheme classes such as vector and matrix static and dynamic, implicit and explicit, algorithmic and heuristic and numeric and symbolic. Resource allocation phase determines the place and the moment for execution of every task to optimize certain performance measure related to some criteria. In the resource allocation domain, the existing Casavant-Kuhl taxonomy is extended and used. This well known taxonomy is supplemented with scheme classes such as noncooperative competitive, noncooperative noncompetitive, and load sharing. In Section III, heterogeneous systems characterized with multiple execution modes ("fully" heterogeneous systems falling in the MESM and the MEMM class) are surveyed. The MESM class systems are described and illustrated with three case studies, two of which support SIMD/MIMD and one supports scalar/vector combination of execution modes. The MEMM class systems are described and illustrated with two representative examples of fully heterogeneous networks supporting multiple execution modes. The system software for heterogeneous computing systems is presented according to an original three-dimensional (3-D) taxonomy whose criteria rely on the level of heterogeneity support implementation, the programming approach, and the data access technique applied. In Section III, several representative heterogeneous applications are described with their computation requirements and the systems used for their execution. Each topic covered in the paper contains several concise examples.

Abstract: This paper describes a case study of building a prototype of an immersive three dimensional (3-D) modeler which supports simple two-handed operations. Designing 3-D objects in a virtual environment has a number of advantages for 3-D geometry creation over designing with traditional computer aided design (CAD) tools. In order to enhance the human-computer interaction in a virtual workspace, two-handed spatial input has been incorporated into a few 3-D designing applications. However, existing 3-D designing tools do not utilize two handed interaction for enhancing the interface sufficiently. Our prototype immersive modeler, VLEGO, employs some features of toy blocks to give flexible two-handed interaction for 3-D design. Features of VLEGO can be summarized as follows: Firstly, VLEGO supports various two-handed operations and hence it makes design environment intuitive and efficient. Secondly, possible location and orientation of primitives are discretely limited so that the user can arrange objects accurately with ease. Finally, the system automatically avoids collisions among primitives and adjusts their positions. As a result, precise design of 3-D objects can be achieved easily by using a set of two-handed operations in intuitive way. This paper describes the design and implementation of VLEGO as well as an experiment for examining the effectiveness of two-handed interaction.

Abstract: The paper provides an assessment of how selected properties of a virtual reality system impact size-distance judgments in a virtual environment Manipulations are made in viewing conditions (biocular vs stereoscopic), image resolution, field of view, scene contrast and target distance, while subjects attempt to match the attributes of a comparison object with a standard object General findings suggest that under more natural viewing conditions, size-distance judgements in virtual environments differ from those found previously in physical environments whereas, under impoverished conditions, performance differences between the two environments are similar