Comparison of approximations of complex objects used for approximation-based query processing in spatial database systems

The minimum bounding box, the convex hull, the minimum bounding four- and five-corner, rotated boxes, and the minimum bounding ellipses and circles convex conservative approximation methods for handling complex spatial objects in spatial access methods are discussed. Results indicate that, depending on the complexity of the objects and the type of queries, the approximations five-corner, ellipse and rotated bounding box clearly outperform the bounding box. It is the reduced number of false hits that yields a considerable improvement in total query time when using the proposed approximations