Skip Nav Destination
Close Modal
Update search
NARROW
Format
Journal
TocHeadingTitle
Date
Availability
1-6 of 6
Chris Greenhalgh
Close
Follow your search
Access your saved searches in your account
Would you like to receive an alert when new items match your search?
Sort by
Journal Articles
Publisher: Journals Gateway
Presence: Teleoperators and Virtual Environments (2005) 14 (4): 423–433.
Published: 01 August 2005
Abstract
View article
PDF
An important property of intelligent virtual agents (IVAs) and multiintelligent virtual agents systems (mIVAS) is their capability to acquire/perceive information from their environment. In this paper we present an auditory perceptual model for IVAs and mIVAS, which extends and reinterprets the key concepts of one of the awareness models developed for computer supported cooperative work (CSCW) applications, the spatial model of interaction (SMI). This perceptual model also introduces some factors typical of human perception—such as auditory acuity—as well as others associated with the sound source and its propagation with the aim of making perception in this kind of system more humanlike.
Journal Articles
Publisher: Journals Gateway
Presence: Teleoperators and Virtual Environments (2003) 12 (1): 68–84.
Published: 01 February 2003
Abstract
View article
PDF
Many VR platforms emphasize extensibility to support as wide a range of applications as possible. The current trend is to move this extensibility to lower levels of the system to support extensibility of infrastructure mechanisms such as networking protocols. This kind of extensibility allows the runtime of the virtual environment system to evolve even while the system is running. This paper presents a new virtual environment platform that allows multiple infrastructure mechanisms to be added to and coexist within the running system, with different elements of the virtual world using different mechanisms. This allows the virtual environment system to efficiently support a wider range of applications by, for example, having only certain virtual objects use conservative consistency and persistence. It can also optimize the performance of the CVE by tailoring the infrastructure mechanisms according to the different roles played by different objects in the virtual environment.
Journal Articles
Publisher: Journals Gateway
Presence: Teleoperators and Virtual Environments (2001) 10 (2): 142–159.
Published: 01 April 2001
Abstract
View article
PDF
Collaborative virtual environments (CVEs) are a promising technology enabling remote participants to share a common place through three-dimensional graphical scenes. Within the COVEN project (Normand, 1999), we have run prolonged series of Internet trials that have allowed us to gather valuable data to formulate usability guidelines and networking requirements. However, running such trials in a real setting and making sure that the application and networking infrastructures will be stable enough is still a challenge. In this paper, we describe some of our experiences, together with the technical choices that have permitted many hours of successful Internet trials. We also make a thorough analysis of different correlated logging data. This analysis allows us to propose and confirm a model of a CVE application's network behavior, together with a number of interesting results that disprove some common assumptions. Furthermore, we use the model and the logging data to highlight the benefits of IP multicasting and for predicting traffic behaviors and bandwidth use on top of different logical network topologies.
Journal Articles
Publisher: Journals Gateway
Presence: Teleoperators and Virtual Environments (2001) 10 (1): 35–50.
Published: 01 February 2001
Abstract
View article
PDF
Inhabited television takes traditional broadcast television and combines it with multiuser virtual reality to give new possibilities for interaction and participation in and around shows or channels. Out of This World was an experimental inhabited TV show, staged in Manchester in September of 1998, using the MASSIVE-2 system. During this event, we captured comprehensive records of network traffic and additional logs of user activity (in particular, movement and speaking). In this paper, we present the results of our analyses of network and user activity in these shows. We contrast our results with those obtained from previous analyses of teleconferencing-style scenarios. We find that the inhabited television scenario results in much higher levels of user activity and significant bursts of coordinated activity. We show how these characteristics must be taken into account when designing a system and infrastructure for applications of this kind. In particular, it is clear that any notion of strict turn-taking (and associated assumptions about resource sharing) is completely unfounded in this domain. We also show that the concept of “levels of participation” is a powerful tool for understanding and managing the bandwidth requirements of an inhabited television event.
Journal Articles
Publisher: Journals Gateway
Presence: Teleoperators and Virtual Environments (1999) 8 (1): 14–35.
Published: 01 February 1999
Abstract
View article
PDF
We focus on the problem of constructing collaborative virtual environments (CVEs) that scale to large numbers of simultaneous participants and yet which still afford rich and varied possibilities for communication. This is achieved by extending our previously defined spatial model of interaction for CVEs to include third-party objects that provide support for contextual factors in awareness calculations and that enhance scaleability. Third parties can have two effects on awareness: attenuation or amplification of existing awareness relationships, and the introduction of new aggregate awareness relationships. We propose a range of applications for third-party objects including world structuring regions, aggregate views, dynamic crowds of participants, common foci, representational and group services, and dynamic load management. We also discuss how the third-party concept relates to other approaches to structuring virtual environments such as tiles, zones, and locales. We then present an implementation, the MASSIVE-2 system, focusing on its network architecture which is based on a dynamic and selfconfiguring hierarchy of multicast groups. Finally, we describe four demonstration applications that have been developed in MASSIVE-2: an environment for staging a public poetry performance that includes semiprivate zones for social interaction; the Panoptican Plaza, which demonstrates a variety of differently bounded regions; a collaborative 3-D Web browser that groups pages into server regions; and the Arena, a performance space that supports both static and mobile crowd aggregations of groups of participants.
Journal Articles
Publisher: Journals Gateway
Presence: Teleoperators and Virtual Environments (1995) 4 (4): 364–386.
Published: 01 November 1995
Abstract
View article
PDF
We explore the issue of supporting cooperative work using networked virtual reality. This exploration covers three major themes: supporting communication and awareness, structuring space, and embodying users. Correspondingly, three sets of concepts are introduced. The first is a spatial model of interaction, which defines the mechanisms of aura, awareness, focus, nimbus, and adapters to allow the inhabitants of virtual environments to flexibly manage their communication across a number of media. The second is a set of techniques for constructing Populated Information Terrains (PITS), abstract data spaces that support the cooperative browsing of information. The third is a set of design issues for virtual bodies. Each set of concepts is illustrated with a discussion of prototype applications implemented within our own DIVE and MASSIVE networked virtual reality systems.