The Pit: a group communication device for teleconviviality Nicolas Roussel Laboratoire de Recherche en Informatique UMR 8623 (CNRS - Université Paris-Sud) 91405 Orsay Cedex, France E-mail:
[email protected]
nication, teleconviviality
ticipants to move away from the formal central focus of the meeting and to gather in smaller informal groups. Therefore, in addition to the traditional audiovisual equipment, we propose to provide users with several other group communication devices allowing sub-groups of local participants to communicate with similar sub-groups from other sites. Together with other more subjective elements such as humor or fun, we expect that these multiple communication foci will contribute to support teleconviviality, that is, the emergence of a relaxed and joyful atmosphere well adapted to distributed informal communication.
INTRODUCTION
THE PIT: OVERVIEW AND CONCEPT
ABSTRACT
This paper presents The Pit, a group communication device designed to support informal meetings. The Pit complements the traditional videoconferencing systems that support more formal meetings. It combines audio and video transmissions with an original design to support teleconviviality, the emergence of a relaxed atmosphere well adapted to distributed informal communication. KEYWORDS: Videoconferencing, informal group commu-
Over the last forty years, a number of audiovisual systems have been proposed to allow people to remotely attend formal meetings. Over the years, multi-point audio and video communication has become easier and cheaper. Image and sound quality has improved a lot, making video-conferencing more and more comfortable. Distant people can now be shown life-size, their voice being spatially mapped to their on-screen location. Although video-conferencing systems have greatly improved in their ability to support formal meetings, they are still hardly usable for the informal discussions that take place before and after the meeting or during breaks. The usual physical location of the cameras, microphones, speakers and monitors favors a global face to face situation, opposing the local participants as a group to the other remote groups [3]. This situation makes it hard for a particular participant to engage in a side conversation with one or more remote participants since they cannot be addressed individually. Hence, during breaks for example, informal discussions usually take place independently at each site, involving only the local participants of the site. We believe that the unique central communication focus that makes traditional video-conferencing systems perfectly suitable for formal meetings is precisely what makes them inappropriate for informal discussions before and after the meeting, or during breaks. One of the keys to supporting informal communication in these contexts is the ability for par-
The Pit [2] is a group communication device that we specifically designed to support teleconviviality. This design was guided by the idea that we wanted to attract a small group of co-located people to an audiovisual device that would allow them to communicate informally with other distant people using similar devices. The Pit looks similar to a high table, ideally oval or circular (Figure 1). Its video communication system consists of a set of cameras and a horizontal display, placed on top of the table. The display shows a graphical composition of the cameras of the other remotely connected Pits and possibly the local ones. The audio communication system consists of a set of microphones and speakers that create a spatialised auditory scene consistent with the graphical display.
Figure 1: An artistic view of the Pit The height of the Pit invites people to stand around it and bend over its curb to look at the display and chat with colocated as well as remote people. The cameras, microphones and speakers are placed so that one must be seen by a camera and heard by a microphone to be able to see the display and hear something. This is a key point of the design: it makes
the Pit more natural to use as well as it simplifies the image and sound capture. The horizontal display has a number of advantages. People need to get to the Pit to fully understand what it is. Although this might sound like a disadvantage, early use showed that curiosity is a very efficient way to attract people to the device. Co-located users can gather in a circle around the Pit, as we usually do when discussing informally. Finally, since the camera images are being displayed on a horizontal surface, there is no notion of up or down. Thus, the images can be laid out in a circle, overlaid or side by side, facing the local users like reflections in water. PROTOTYPING THE PIT
Two Pit prototypes have been built (Figure 2). In order to simplify the design, these prototypes are rectangular rather than circular. A video projector and a mirror are placed inside each Pit, the image being back-projected onto an etchedglass tabletop. Three thumb-size analog video cameras and three speakers are placed inside three of its curbs, around the display. Three directive cardioid microphones hang over the display, far enough from the speakers to reduce acoustic coupling and avoid echo and feedback effects. Figure 3: Sample compositions of images. Added symbols show that mutual orientation is preserved ticipated factors, such as lighting conditions or the nature of the background. CONCLUSION AND FUTURE WORK
Figure 2: The two prototypes and a close-up Each Pit includes an SGI O2 workstation running the video compositing software. The software uses the videoSpace toolkit [1] to manage the video streams and OpenGL for display. VideoSpace allowed us to experiment with analog as well as digital video transmissions between the two Pits (audio signals are always transmitted on analog cables). It also allowed us to record typical video streams taken from the cameras and test various compositing techniques. The current compositing process removes uninteresting parts of the images, such as the corners, by applying a transparency mask and then combines them so as to preserve the mutual orientation of the users (Figure 3). Informal user testing shows that the Pit is very well received. As anticipated, people are attracted to it and are able to communicate with the remote participants spontaneously, without training. Observations met our original expectations about the emergence of a sense of teleconviviality. The prototypes also helped us to understand the importance of some unan-
We have introduced a novel device for remote informal communication based on a horizontal display and a spatialised sound system that support a consistent audiovisual scene between local and remote sites. Informal evaluations of this device are promising and open the way to new research. We plan to continue this work by experimenting other designs for the Pit including shared interaction through digital and physical objects to complement communication and enhance teleconviviality. ACKNOWLEDGEMENTS
This work was supported by France Télécom R&D as part of the Telemedia project. The author would like to thank Michel Beaudouin-Lafon, Jacques Martin, Jean-Dominique Gascuel and the other people from CSTB and iMAGIS who contributed to the design and prototyping of the Pit. REFERENCES
[1] N. Roussel. Exploring new uses of video with videoSpace. In Proceedings of EHCI’01, Lecture Notes in Computer Science. Springer-Verlag. 18 pages, to be published. [2] N. Roussel, M. Beaudouin-Lafon, J. Martin, J.-D. Gascuel, G. Buchner, and H. Lissek. Terminal et système de communication. Patent pending, July 2000. [3] E. Williams. Coalition formation over telecommunications media. European Journal of Social Psychology, 5:503–507, 1975.
