Integrating GIS and Imagery Through XML-Based Information Mediation

Integration of information from distributed, heterogeneous information sources is an active area of research in the database community. The research efforts have mainly concentrated on sources such as collections of web documents, relational databases and text files. In the domain of spatial information systems, researchers have studied integration architectures, issues and problems in semantic interoperability and information integration concepts for spatial data [0,0, 0]. Some recent approaches [14, 15, 19] have applied information integration methodology from the database community to spatial information systems. In this paper, we propose a mediation-based approach for integrating information from two types of information sources, viz. spatial information systems such as GIS and searchable databases of geo-referenced imagery. As in [14,19], our goal is to enable users to issue a single query in order to search multiple information sources and, in return, receive a combined result incorporating data from across these sources. Similarly, we would like to provide authenticated and authorized users the ability to update sources. This paper describes the architecture of a mediation-based system and steps through the query evaluation procedure in an such a system. We emphasize that the notion of “integration” addressed in this paper does not rest on the development of spatial algorithms that operate on images or vector data and achieve “physical integration” (e.g., see [11]) through techniques like image conflation, as described in, say, [11]. Instead, we aim to attain “logical integration” by creating correspondences between related spatial information similar to non-spatial mediation systems [10]. We demonstrate how existing physical integration techniques can fit into our information association methodology. However, the development of such methods is not the focus of this paper.