A method for merging polygons in adjacent tiles is provided that includes determining that a first polygon in a tile having a first edge linked list and a second polygon in an adjacent tile having a second edge linked list have overlapping invalid edges, wherein an edge includes an ordered set of point coordinates in which an initial two point coordinates lie on a tile boundary and last point coordinates of the set also lie on a tile boundary, and an edge linked list is an ordered list of edges of a polygon, and merging the first edge linked list and the second edge linked list to generate a third edge linked list for a merged polygon comprising the first polygon and the second polygon.