Interaction Control Protocols for Distributed Multi-user Multi-camera Environments Gareth W DANIEL and Min CHEN Department of Computer Science, University of Wales Swansea Swansea, SA2 8PP, UK ABSTRACT Video-centred communication (e.g., video conferencing, multimedia online learning, traffic monitoring, and surveillance) is becoming a customary activity in our lives. The management of interactions in such an environment is a complicated HCI issue. In this paper, we present our study on a collection of interaction control protocols for distributed multi- user multi-camera environments. These protocols facilitate different approaches to managing a user’s entitlement for controlling a particular camera. We describe a web-based system that allows multiple users to manipulate multiple cameras in varying remote locations. The system was developed using the Java framework, and all protocols discussed have been incorporated into the system. Experiments were designed and conducted to evaluate the effectiveness of these protocols, and to enable the identification of various human factors in a distributed multi-user and multi-camera environment. This work provides an insight into the complexity associated with the interaction management in video-centred communication. It can also serve as a conceptual and experimental framework for further research in this area. Keywords Video-centred communications, distributed systems, camera control, interaction protocols, human-computer interaction, interaction management, interactive systems and models. 1. INTRODUCTION Even in the early days of the Internet, with the ARPANET project, we see the inherent desire for interactive communi- cation. With the rapid development of network infrastructures and streaming media technologies, video-centred communication is becoming a customary activity in our life. Some of us frequently hold multi-site videoconferences, whilst others sometimes stream lectures to remote classes. Many of us have had at least a glimpse of a big-brother house on the TV or the Internet, whilst most of us are constantly captured by traffic or surveillance cameras. There is an ever- increasing scope for a distributed interactive environment involving multiple users and multiple cameras. The interaction in such an environment is usually complex and difficult to manage. The studies on the relevant interaction control protocols are particularly scarce. One interesting feature of video-centred communication is that it can offer only a limited view of what is being filmed, which raises the desire of a viewer to gain control of the camera. Such a technical feature and its associated human factors are uncommon in text-, image-, or audio-centred communications. In other words, video-centred communication presents us a collection of HCI issues to be explored. An understanding of these issues would help answer many questions in designing software systems and user interfaces for video-centred communication. For example, • in designing a remote meeting and collaboration environment, shall we restrict camera control locally, or make each camera controllable by all sites? • in designing a web-based traffic monitoring system, what would happen if we allow web users to have simultaneous control of the cameras involved? • in designing an area-surveillance system, how can we moderate the control of the cameras among different monitoring stations? Such questions encompass a range of general as well as application-specific issues. In particular, the following three interrelated aspects of interactions represent the fundamental human factors that underpin a scientific answer to such questions: 1) Human-Computer Interaction (HCI) — how the users may interact with the cameras. 2) Human-Human Interaction (HHI) — how the users may coordinate the camera control among themselves. 3) Human-Computer-Human Interaction (HCHI) — how the system facilitates, moderates and manages user actions for manipulating the cameras. This paper will focus on the HCHI aspect, whilst considering HCI and HHI whenever appropriate. In particular, we will present our study on different interaction protocols for managing the communications associated with camera controls. In our study, we have considered the abstract notions of interaction protocols, which address the generalised needs of many applications. We have demonstrated the technical feasibility of implementing these protocols through the development of an environment where a set of advanced technologies are integrated together. We have also conducted experiments that emulate a multi-user, multi-camera surveillance environment where such interaction protocols may be deployed. Our experimental results have demonstrated the relative merits of the protocols studied, and offered an insight into how these protocols may affect the management of interactive activities and the effectiveness of HCHI. SYSTEMICS, CYBERNETICS AND INFORMATICS VOLUME 1 - NUMBER 5 29