Research On Direction Relation Reasoning For Linetype Objects

Qualitative spatial reasoning is an absolutely necessary part of the study about the application of spatial database and Geography Information System, and the direction relation study of qualitative spatial reasoning is one hotspot in the research area of qualitative spatial reasoning. As an important part in the researching area of qualitative spatial reasoning, the direction relation reasoning of linetype objects has a hopeful and extensive future of application, so this paper carries on studies and explores in the aspect of direction relation reasoning based on linetype objects.Models of spatial direction relations are summarized in this paper. Based on the minimum boundary rectangle model of spatial area objects, the cardinal direction relations model of linetype objects is put forward. Cardinal direction relations of linetype objects are studied farther and the study is based on the established cardinal direction model of linetype objects. A method is put forward by combining the theory of Interval Algebra and Rectangle Algebra to express cardinal direction relations of linetype objects, using the rectangle algebra of projective intervals. This method is in favor of the operation of cardinal direction relations reasoning for linetype objects, and of the realization of the network consistency checking as well.Inversion operation, intersection operation and composition operation with cardinal direction relations of linetype objects are studied farther in this paper. Corresponding definitions and theorems of them are put forward, and the reasoning operation methods of projection sections relations applied to projective interval relations, cardinal direction relations and multi-cardinal direction relations in every forenamed operation are analyzed concretely. Convex relations in the cardinal direction relations model of linetype objects are analyzed in detail. The judging method of convex relations in cardinaldirection relations of linetype objects is provided. This method and algorithm of consistency checking for cardinal direction relation networks are proposed by combining the convex relation network theorem and path consistency checking algorithm, as well as the corresponding correctness proof and the algorithmic analysis are given in the end.