Massive

We describe a prototype virtual reality teleconferencing system called MASSIVE which has been developed as part of our on-going research into collaborative virtual environments. This system allows multiple users to communicate using arbitrary combinations of audio, graphics, and text media over local and wide area networks. Communication is controlled by a so-called spatial model of interaction so that one user's perception of another user is sensitive to their relative positions and orientations. The key concept in this spatial model is the (quantitative) awareness which one object has of another. This is controlled by the observing object's focus and the observed object's nimbus , which describe regions of interest and projection, respectively. Each object's aura defines the total region within which it interacts. This is applied independently in each medium. The system (and the spatial model which it implements) is intended to provide a flexible and natural environment for the spatial mediation of conversation. The model also provides a basis for scaling to relatively large numbers of users. Our design goals include supporting heterogeneity, scalability, spatial mediation, balance of power, and multiple concurrent meetings; MASSIVE meets all of these goals. Our initial experiences show the importance of audio in collaborative VR, and they raise issues about field of view for graphical users, speed of navigation, quality of embodiment, varying perceptions of space, and scalability.