Efficient algorithm for polygon overlay for dense map image data sets

A map consists ofufinite set of mutually disjoint polygons. A data structure and ~~~~ent ulgor~t~m for polygon over1uy of dense map image data sets are d~s~u.~sed. The data structure, referred to as the ending-x structure, is a variant qf the y-partition structure developed by Merrill which is still bcidely acclaimed as an optimum raster data structure. The modest refinement of the ending-x structure ,further reduces raster data volume, More iinportantly, it can sign~~i~ant~v enhance the prowess of polygon overia~ for multiple map image data sets. Considering the density of many map image data sets, and the significance of the polygon overlay problem to spatial data handling, these are signijicant advances. The paper describes the ending-x data structure and compares the algorithm for polygon overiay suggested by ~~erri~~ with one emplo.ying the ending-x structure.