Spatial queries based on direction relations with the case of vector rivers data

An algorithm is proposed in this paper to realize the spatial queries based on direction relations. This includes two procedures: first, the algorithm searches the objects whose MBRs meet the given directions by using the cone-based model and improved quad-tree to construct the candidate set; second, the result set will be got by removing the objects that can not meet the given directions in the candidate set. Types of vector rivers data have been selected to test the correctness and efficiency of the algorithm, and the experiments show that the algorithm can greatly improve the query efficiency and can be directly used in spatial database retrieval.