Supporting Direction Relations in Spatial Database Systems

Despite the attention that direction relations have attracted in domains such as Spatial Query Languages, Image and Multimedia Databases, Reasoning and Geographic Applications, they have not been extensively applied in spatial access methods. In this paper we define direction relations between two-dimensional objects in different levels of qualitative resolution and we show how these relations can be efficiently retrieved in existing DBMSs using several indexing techniques. Then we describe our implementations and provide experimental results on B- and R- tree-based data structures to support direction relations efficiently. Keywords: Direction relations, Spatial Data Structures, Query Optimisation. 1. INTRODUCTION There has been an increasing interest recently about the representation and processing of spatial relations in Spatial Database Systems (for an extensive discussion see [Papa94c]). This interest has focused on several topics such as Reasoning [Fran95], Consistency Checking..