Large Scale Collaborative Virtual Environments

Collaborative virtual environments are multi-user virtual realities which actively support communication and co-operation. This book addresses the theory, design, realisation and evaluation of such systems, with a particular emphasis on support for large numbers of distributed users. A broad approach is taken, which ranges from the sociology of interpersonal communication to the management of communication in distributed systems. The emphasis on multi-user environments distinguishes this book from the many general books on virtual reality which only deal with single-user systems. This book presents: models of multi-party awareness and interaction in space-based systems; detailed designs of two prototypes (MASSIVE-1 and MASSIVE-2); experiences with collaborative virtual environments created using these; and analyses of the corresponding network requirements. Many of these results and ideas are applicable to other systems and approaches.

A Collaborative Virtual Environment (CVE) is a distributed, virtual reality designed to support collaborative activities. It is a topic of increasing interest to large global corporations, where work teams are often distributed over a large geographic area. Aimed at anyone involved in researching the design of tools for supporting distributed teams of workers, it helps the reader understand the latest technology, state-of-the-art research, and good working practice. Among the topics covered are: systems aspects of CVEs; user centered aspects of environment design; and methodologies for iterative evaluation and design.

Collaborative Virtual Environments (CVE) are virtual reality spaces that enable participants to collaborate and share objects, as if physically present in the same place. CVE concepts have been used in many systems in the past few years. Applications of such technology range from military combat simulations to various civilian commercial applications. These collaboration spaces have strict performance requirements. Today, there are many such systems developed specifically for collaboration. At the same time, some relatively new standards that address multiuser virtual environments and shared spaces have become available; however, most of these standards have been developed assuming that a small number of users would be interacting at a given time. The architectures available today provide support for a modest number of users but they fail if too many users are "present" together in a small "space" in the Virtual World. In this work, we first evaluate the currently available standards for the case of a very large number of users. An Adaptive Hybrid Architecture for VEry Large Virtual EnvironmenTs (VELVET) is then introduced. VELVET allows a large number of users to interact in a CVE. It also supports small groups of users, but it is in the large environment case that shows its greatest potential. VELVET introduces a novel adaptive area of interest management, which supports heterogeneity amongst the various participants. That allows users in a supercomputer with a high-speed networking connection to successfully collaborate with others in not-so-powerful systems behind a slow dial-up connection. In order to make a Collaborative Virtual Environment more interesting to users, it is possible to "stitch" together copies of areas which users may have interest in from one Virtual World into another. This procedure augments the physical size of a Virtual World, and creates a potentially larger number of users within the World, first because of the "embedding" and second since the added attractions may work as an incentive for some more users to join the "embedded" World. On the other hand this procedure brings up a series of problems related with consistency, which are also addressed in the thesis. We introduce a methodology which ensures that all copies of a given area of a World are kept consistent among them, as well as with the original world. We also apply this methodology in VELVET, as well as in other Architectures. Additionally, we introduce other approaches to be used when a less strict consistency model is sufficient.

Collaborative virtual environments are multi-user virtual realities which actively support communication and co-operation. This book addresses the theory, design, realisation and evaluation of such systems, with a particular emphasis on support for large numbers of distributed users. A broad approach is taken, which ranges from the sociology of interpersonal communication to the management of communication in distributed systems. The emphasis on multi-user environments distinguishes this book from the many general books on virtual reality which only deal with single-user systems. This book presents: models of multi-party awareness and interaction in space-based systems; detailed designs of two prototypes (MASSIVE-1 and MASSIVE-2); experiences with collaborative virtual environments created using these; and analyses of the corresponding network requirements. Many of these results and ideas are applicable to other systems and approaches.

Collaboration is often a necessity in order to reach one's goals in society, organizations, or among individuals. Collaborative Virtual Environments (CVEs) can be used as a medium supporting interaction between people. By allowing real-time co-work with graphical representations, they offer new possibilities to facilitate collaboration. Yet, while the use of CVEs is continuously increasing, there is still little research on understanding the consequences of using them as a social medium. Based on five experimental studies, users' experiences and their performance were comparatively evaluated for different CVE technologies. It was found that although immersive technologies provided greater presence, effectiveness varied more with the tasks than with the technology used. The symmetry or asymmetry in the distributed settings was also found to have a major impact on effectiveness. By focusing on social interaction, interaction via technology and problem solving separately, small sequences of successes and failures during collaboration were analyzed, and a framework for usability evaluation for CVEs developed. The results also support selection of different types of CVE.