This paper discussed a distributed processing architecture for a virtual space teleconferencing system. Virtual space teleconferencing is a promising application field for networked virtual environments. People in different places will be able to meet each other in a virtual teleconferencing room and proceed with various cooperative tasks. When such a system creates a realistic virtual environment, it can be referred to as a "Teleconferencing with realistic sensations" system. Further more, as the conference environment can be shared by a number of users, it is possible to perform various kinds of cooperative work using the system. In this paper, the architecture for networked multi-user virtual space systems are classified, and then a case study is described for building a proposed teleconferencing system. The system reproduces a 3D image of each conference participant in a virtual meeting room. Compared with the former system, the new system can deal with more than three participants at the same time and can connect them through commercial telephone lines. Based on the virtual world database management structure, the system was classified as a central server system. However, a central server architecture limits the number of conference sites. We confirmed that the system can serve up to 14 sites using multi-modal interaction without significant latency in operation from summational experiments. Then, introducing some assumptions to the results, we have proposed processing model of the system. The results of model could describe the experimental results and we could indicate roughy estimated system capacity to realize a requaied system performance.

Recently, studies aiming at the next generation of visual communication services which support better human communication have been carried out intensively in Japan. The principal motive of these studies is to develop new services which are not restricted to a conventional communication framework based on the transmission of waveform signals. This paper focuses on three important key words in these studies; "intelligent," "real," and "distributed and collaborative," and describes recent research activities. The first key word "intelligent" relates to intelligent image coding. As a particular example, model-based coding of moving facial images is discussed in detail. In this method, shape change and motion of the human face is described by a small number of parameters. This feature leads to the development of new applications such as very low bit-rate transmission of moving facial images, analysis and synthesis of facial expression, human interfaces, and so on. The second key word "real" relates to communication with realistic sensations and virtual space teleconferencing. Among various component technologies, real-time reproduction of 3-D human images and a cooperative work environment with virtual space are discussed in detail. The last key word "distributed and collaborative" relates to collaborative work in a distributed work environment. The importance of visual media in collaborative work, a concept of CSCW, and requirements for realizing a distributed collaborative environment are discussed. Then, four examples of CSCW systems are briefly outlined.