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Communications of the ACM

Communications of the ACM

Representation of contours and regions for efficient computer search

A novel computer-searchable representation for the three basic pictorial features, contour maps, region coverage, and line structures, is described. The representation, which has practical storage requirements, provides a rapid means of searching large files for data associated with geometric position as well as with attribute value. An application of this representation to handling terrain information illustrates its utility. The algebraic properties of the data structure make it computationally easy to determine whether a point lies within a closed boundary; compute the area contained by a closed boundary; generate the closed boundary representing the union or intersection of two closed boundaries; and determine the neighboring boundaries to a point and the minimum distances between them and the point.

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