Examples of CVEs

CVEs were developed in various forms for purposes such as virtual busi- ness meetings, scientific co-visualisation, virtual therapy, and entertainment (Schroeder 1996, pages 1-2). The following paragraphs provide examples of CVEs within the classification of social online 3D environments and research systems.

Social online 3D environments: along with the explosion of the inter- net, several virtual environments emerged that follow the spatial interaction model. In these systems, graphical 3D environments or virtual worlds are displayed on a 3D browser application running on standard PCs. Users are

embodied as a variety of avatars which are placed in persistent 3D virtual worlds where they can communicate, mingle, and play with others for the purpose of entertainment. Social online 3D environments can be further subclassified into massively multiplayer online games (MMOG) and online worlds for socialising.

MMOG such as World of Warcraft8 _{or Dungeons and Dragons}9 _{foster the}

idea of role-playing within a given fictional plot and fantasy world. Groups of avatars either compete or cooperate in order to reach the goal defined by the game.

Online 3D worlds built for socialising such as Active Worlds10, There 11, and Second Life12, however, do not encourage role-playing, but rather allow users to portray themselves in a virtual world where they may interact with others, visit and build there own worlds, and even purchase or sell virtual objects and services. The idea behind creating a virtual world which is similar to the real world, but without physical limitations, has its roots in the vision of the Metaverse, as described in Stephenson’s (1992) science fiction novel “Snow Crash”.

Commercial social online 3D environments gained significant popularity and attention over the last five years and were able to create virtual commu- nities counting millions of members distributed over the whole globe, with new members signing up every day.

Researchers recognised these systems as a valuable resource for studying social phenomena relevant to the field of CSCW such as the dynamics of establishing a virtual community (Hudson-Smith 2002), the design and use of 3D virtual worlds (Hansen 2002), forms of appropriation by users (Brown and Bell 2004), as well as the characteristics of collaborative play (Nardi and Harris 2006).

8_{www.worldofwarcraft.com/, last accessed July 2007.}

9_{www.wizards.com/default.asp?x=dnd/welcome, last accessed July 2007.} 10_{www.activeworlds.com, last accessed July 2007.}

11_{www.there.com/, last accessed July 2007.} 12_{www.secondlife.com/, last accessed July 2007.}

Research systems: Experimental CVE platforms were developed in var- ious computer science labs since the mid-1990s aiming to explore the design space of this new technology. Trial systems and prototypes often made use of complex and cutting-edge technology such as high-end computer graph- ics hardware and immersive stereo displays, as well as specialised input and output devices. In the following, two representative CVE research platforms are described in more detail.

• MASSIVE: The research initiative MASSIVE (Model, Architecture, and System for Spatial Interaction in Virtual Environments) was an early attempt to develop a CVE for teleconferencing (Greenhalgh and Benford 1995). MASSIVE realised several scenarios that were inspired by the spatial model of interaction that Benford et al. (1994) had de- veloped earlier. As such, MASSIVE implemented forms of negotiating awareness through the use of aura (a subspace within which an object interacts), focus (the more an object is within your focus, the more aware you are of it), and nimbus (the more an object is within your nimbus, the more it is aware of you) and demonstrated the basic func- tionality of first, crude prototypes in distributed settings. MASSIVE also served as a test bed for later user tests (e.g. Bowers et al. 1996) and was eventually developed further in the system “MASSIVE-2” which allowed for the integration of further contextual factors for improved awareness (Benford and Greenhalgh 1997).

• COVEN: The goal of the European COVEN (COllaborative Virtual ENvironments) project was to develop a comprehensive understand- ing of the nature of CVEs, and to develop a sophisticated platform for next-generation CVEs (Normand et al. 1999, Fr´econ et al. 2001). The project lasted for four years and involved twelve academic and in- dustry partners. CVE prototypes were developed based on the DIVE (Distributed Interactive Virtual Environment) toolkit (Carlsson and Hagsand 1993, Fr´econ and Stenius 1998), which was improved and ex- tended in the course of the project. The main improvements that the COVEN project brought forward include humanoid avatars featuring

a dynamic level of detail and motion control, a streamlined network- ing data infrastructure, and the modular integration of spatial sound as well as video. In addition to these technological achievements, usability factors of several application scenarios including a virtual conference, interior arrangement, and travel rehearsal were explored.

As part of the COVEN initiative, a new visualization technique, “sub- jective views”, was also introduced as proposed earlier by Smith (1996) which allows two participants who share the same VE to tailor their view of shared objects to highlight or de-emphasise visual features ac- cording to their individual needs. A virtual table could thus appear as solid geometry for one user while the same table might appear as a wire frame for the other user.

To allow rapid development of customised CVE prototypes within the COVEN platform, Fr´econ and Smith (1999) developed the high-level behaviour language DIVE/TCL, which allows researchers easy access to otherwise complex state-of-the-art CVE technology.