Graph-based consistency checking in spatial information systems

Consistency checking of cardinal directions is one of the important problems in qualitative spatial reasoning. This paper presents a graph model to visually represent direction specifications. In the model, nodes represent regions occupied by objects, and directed edges indicate direction relationships between objects. This graph model can be applied not only to consistency checking, but also to general spatial reasoning. Based on this model, we present an efficient algorithm that performs consistency checking on a set of definitive direction specifications by analyzing the connectivity of the participating nodes. The consistency checking algorithm is performed in O(n/sup 4/) time.