This paper discusses ways to incorporate video displays into virtual environments. It focuses on the virtual worlds created by a distributed multi-user simulator. Still images or video streams represent spaces within these three-dimensional worlds. The paper introduces techniques to deal with avatar movement into and out of video regions. In one technique—media melding—when an object moves from one region to another, the media used to represent that object correspondingly change. In a second technique—object tracing—when an object moves from one region to another, its actions in the second region are represented by a trace object in the first region. Pyramidic panels provide a means of dealing with viewpoint changes so that two-dimensional images and video clips can successfully simulate three-dimensional spaces. The paper concludes by suggesting ways to extend our techniques and by listing possible future studies.

No abstract available.

The Rapport multimedia conferencing system supports interactive real-time distributed conferences among two or more people. Rapport executes on personal workstations interconnected by data and voice networks. It is designed to help people emulate face-to-face conferences as closely as possible with their workstations. These conferences can be of different type, including phone conversations, group meetings, or lectures. The authors describe the Rapport system and elaborate on its networking requirements. Based on experience with their initial prototype system, the authors highlight some of the current networking limitations and examine future directions, such as broadband communication, for alleviating these problems.>

Abstract This paper describes a proposal for a modification to the language Modula. The modification was motivated by a desire to bring to the language the ability to build hierarchical systems and to support program verification efforts. In the modified language, called SB‐Mod, modules are grouped into levels and calls are permitted from the modules of one level to those of a higher level. Verification is supported through a set of clearly described synchronization constructs and by restricting the flow of information between levels. A result of this is that levels do not interfere with each other and can be treated separately for purposes of verification. In considering modifications, an attempt was made to provide the user with a variety of control mechanisms, while at the same time avoiding situations in which excessive run‐time overhead would be incurred.