Toward Spatial Joins for Polygons

Efficient evaluation of spatial join is an important issue in spatial databases. The traditional evaluation strategy is to perform a join of “minimum bounding rectangles” (mbr) of the spatial objects (mbr-filter) and evaluate the actual join of the objects using the results of the join on approximations. Improvements to add additional filtering using more accurate approximations were also considered. In the present paper, we develop efficient algorithms for evaluating joins of “trapezoids” without using mbr’s. For the case where there are no intersecting non-horizontal boundaries of trapezoids in the same set, a spatial join of two sets of N trapezoids can be evaluated in O(N logb N+k) I/Os, where b is the page size and k the number of trapezoid intersections. For the general case without any assumptions, a join can be done in O((N+l+k) logb N) I/Os, where l is the total number of intersections of non-horizontal boundaries within the same set, and N, k, b are the same as a...

• Type: Conference
• Year: 2000
• Where: SSDBM
• Authors: Hongjun Zhu, Jianwen Su, Oscar H. Ibarra
• Keywords: Database, I/O Bounded Polygons, Non-horizontal Boundaries, Spatial Joins, SSDBM 2000