Shapefile Overlay Using a Doubly-Connected Edge List
نویسنده
چکیده
We present a method for finding the overlays of a set of polygons that uses the doubly-connected edge list structure. We first detect all intersections between polygons using a brute-force method. We then build the doubly-connected edge list, maintaining information about the original polygons, from which we can easily perform shapefile overlay operations: intersection, difference, and union. Our algorithm runs in O(n) time. Our doubly-connected edge list construction algorithm runs in O(n log(n)) time, with the bottleneck being the brute-force O(n) line segment intersection. Once that list is built, any given overlay operation is O(n).
منابع مشابه
SPReAD: On Spherical Part Recognition by Axial Discretization in 4D Hough Space
A novel algorithm is proposed to locate the sets of adjacent co-spherical triangles for a given object, which enables us to detect spheres and spherical parts constituting the object. An extension of the idea of Hough transform has been used, aided by axial discretization and restricted searching, along with the geometric data structure of doubly connected edge list. The algorithm has been anal...
متن کاملVoronoi diagrams in Cgal
In this paper we describe a generic C++ adaptor, that adapts a 2-dimensional triangulated Delaunay graph and to the corresponding a Voronoi diagram, represented as a doubly connected edge list (DCEL) data structure. Our adaptor has the ability to automatically eliminate, in a consistent manner, degenerate features of the Voronoi diagram, that are artifacts of the requirement that Delaunay graph...
متن کاملThe spherical visibility map
We introduce a novel representation for visibility in three dimensions and describe an efficient algorithm to construct it. The data structure is a spherical map that consists of a doubly–connected edge list embedded on the surface of a sphere. Each face of the spherical map is labeled with the polygon visible in the corresponding cone. We demonstrate that the algorithm is efficient and robust ...
متن کاملA 3D Molecular Surface Representation Supporting Neighborhood Queries1
Applications in molecular biology more and more require geometric data management along with physicochemical data handling. Thus, 3D structures and surfaces of molecules become basic objects in molecular databases. We propose the neighborhood query on graphs such as molecular surfaces as a fundamental query class concerning topological information on patch adjacency. Furthermore, we suggest a p...
متن کاملA 3D Molecular Surface Representation Supporting Neighborhood Queries
Applications in molecular biology more and more require geometric data management along with physicochemical data handling. Thus, 3D structures and surfaces of molecules become basic objects in molecular databases. We propose the neighborhood query on graphs such as molecular surfaces as a fundamental query class concerning topological information on patch adjacency. Furthermore, we suggest a p...
متن کامل