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Mediaspaces have been designed to facilitate informal communication and support group awareness while assuring privacy protection. However, low bandwidth communication is a source of undesirable discontinuities in such systems, resulting in a loss of peripheral awareness. In addition, privacy is often implemented as an accessibility matrix coupled to an all-or-nothing exposure of personal state. In this article, we describe CoMedi, a mediaspace prototype that addresses the problem of discontinuity and privacy in an original way: computer vision and speech recognition are used in conjunction to minimize visual discontinuities while supporting free movements in a room. Publication filters maintain privacy at the desired level of transparency.

The current solutions to disclosing privacy in computer-mediated communication are two-fold: either the connection is permitted and an audio-video link is opened providing a full-blown perceptual view on the distant location, or the connection is denied and the distant visitor has no perceptual access to the remote site. We claim that the disclosure of private data is more complex than these simplistic binary solutions. In this article. we present the concept of published observability as a system property to characterize the disclosure of private data. We propose a technical solution as an instantiation of this property using an eigen-space coding for private video data. This technique has been implemented within CoMedi, a mediaspace under development.

In Computer Mediated Communication, static video cameras provide a restricted field of view of remote sites. The concept of virtual window has been introduced to alleviate this problem. Although this technique is interactionally attractive, early implementations have proved unsatisfactory because of lack of robustness. In this paper, we demonstrate that robustness and accuracy can be increased by combining multiple computer vision techniques such as eye blink detection, skin color histogram and cross correlation, that adapt to a variety of operating conditions.

Computer vision provides a powerful tool for the interaction between man and machine. The barrier between physical objects (paper, pencils, calculators) and their electronic counterparts limits both the integration of computing into human tasks, and the population willing to adapt to the required input devices. Computer vision, coupled with video projection using low cost devices, makes it possible for a human to use any convenient object, including fingers, as digital input devices. In such an “augmented reality”, information is projected onto ordinary objects and acquired by watching the way objects are manipulated. In the first part of this paper we describe experiments with techniques for watching the hands and recognizing gestures.

We propose the CARE properties as a simple way of characterising and assessing aspects of multimodal interaction: the Complementarity, Assignment, Redundancy, and Equivalence that may occur between the interaction techniques available in a multimodal user interface. We provide a formal definition of these properties and use the notion of compatibility to show how the system CARE properties interact with user CARE-like properties in the design of a system. The discussion is illustrated with MATIS, a Multimodal Air Travel Information System.