A Qualitative Spatial Reasoner*

Traditionally, GISs employ purely quantitative methods to represent and infer spatial information. This approach has serious shortcomings when dealing with qualitative spatial information, which may be incomplete or imprecise and without knowledge of the particular geometry of the spatial objects involved. This paper describes efforts to build a prototype of a qualitative spatial reasoner about spatial relations such as topological relations, cardinal directions, and approximate distances. It builds on relation algebras developed for the individual spatial relations. The system is extensible as demonstrated by the inclusion of temporal relations. The novel concept in this object-oriented setting is the treatment of relations as first-class objects, rather than as labeled links between spatial objects.