Integration of a fuzzy query framework with existing spatial query languages

The representations of spatial relationships among multidimensional features and subsequent querying of these relationships are two areas wherein the application of fuzzy concepts has tremendous potential. Of particular interest to us are the sets of qualitative topological and directional relationships for geographical data of two dimensions. These sets form a substantial part of relationships in which users of spatial information systems are interested. Furthermore, these relationships are best described and interpreted by humans when some degree of fuzziness is allowed, as it is very difficult to precisely determine for example, whether one area feature is exactly northwest of another area feature. More likely, there is more than one applicable directional relationship between the two, and a precise categorization will lead to some degree of loss of information and subsequent misinterpretation of geographic reality. Many existing systems, unfortunately, do not allow for either the fuzzy representation or querying of such relationships. In this paper, we show how, using a previously defined fuzzy data model and low-level query framework for spatial relationships, the capability for providing such fuzzy modeling and querying of spatial relationships can be integrated into existing query systems. Specifically, we show the application of these concepts to the query languages Spatial SQL, Pictorial SQL (PSQL) and PICQUERY/sup +/.