Issues of representing context illustrated by video-surveillance applications

This paper tackles several issues of context representation in knowledge-based systems. First, we propose a definition of context through the description of the different types of information manipulated by a process. Thanks to this definition we explain the role of the granularity level of processing and the role of the abstraction level of application in modelling context. Based on this definition two main issues related to context are tackled: how context representation can be built and organized and how context contents can be re-used for other applications. Then we propose several solutions to deal with these issues: using a multi-viewpoint representation and describing context through symbolic information. We illustrate the proposed context model with the process of dynamic scene interpretation. After explaining the reasons why this process is particularly concerned with the use of contextual information, we describe the context representation and its implementation for this specific process. Finally, we give an example illustrating the utilization of the context representation and we describe the software we have developed to ease the acquisition stage of context contents. (C) 1998 Academic Press Limited.