include/geos/opOverlay.h

   1 /**********************************************************************
   2  *
   3  * GEOS - Geometry Engine Open Source
   4  * http://geos.osgeo.org
   5  *
   6  * Copyright (C) 2005-2006 Refractions Research Inc.
   7  * Copyright (C) 2001-2002 Vivid Solutions Inc.
   8  *
   9  * This is free software; you can redistribute and/or modify it under
  10  * the terms of the GNU Lesser General Public Licence as published
  11  * by the Free Software Foundation.
  12  * See the COPYING file for more information.
  13  *
  14  **********************************************************************/
  15
  16 #ifndef GEOS_OPOVERLAY_H
  17 #define GEOS_OPOVERLAY_H
  18
  19 namespace geos {
  20 namespace operation {
  21
  22 /** \brief
  23  * Contains classes that perform a topological overlay to compute boolean
  24  * spatial functions.
  25  *
  26  * The Overlay Algorithm is used in spatial analysis methods for computing
  27  * set-theoretic operations (boolean combinations) of input {@link Geometry}s.
  28  * The algorithm for computing the overlay uses the intersection operations
  29  * supported by topology graphs.
  30  * To compute an overlay it is necessary to explicitly compute the resultant
  31  * graph formed by the computed intersections.
  32  *
  33  * The algorithm to compute a set-theoretic spatial analysis method has the
  34  * following steps:
  35  *
  36  *  - Build topology graphs of the two input geometries.  For each geometry all
  37  *    self-intersection nodes are computed and added to the graph.
  38  *  - Compute nodes for all intersections between edges and nodes of the graphs.
  39  *  - Compute the labeling for the computed nodes by merging the labels from
  40  *    the input graphs.
  41  *  - Compute new edges between the compute intersection nodes.
  42  *    Label the edges appropriately.
  43  *  - Build the resultant graph from the new nodes and edges.
  44  *  - Compute the labeling for isolated components of the graph.  Add the
  45  *    isolated components to the resultant graph.
  46  *  - Compute the result of the boolean combination by selecting the node
  47  *    and edges with the appropriate labels. Polygonize areas and sew linear
  48  *    geometries together.
  49  *
  50  * <h2>Package Specification</h2>
  51  *
  52  * - Java Topology Suite Technical Specifications
  53  * - <A HREF="http://www.opengis.org/techno/specs.htm">
  54  *   OpenGIS Simple Features Specification for SQL</A>
  55  *
  56  */
  57 namespace overlay { // geos.operation.overlay
  58
  59 } // namespace geos.operation.overlay
  60 } // namespace geos.operation
  61 } // namespace geos
  62
  63 #include <geos/operation/overlay/OverlayOp.h>
  64 //#include <geos/operation/overlay/PolygonBuilder.h>
  65 //#include <geos/operation/overlay/PointBuilder.h>
  66 //#include <geos/operation/overlay/LineBuilder.h>
  67 //#include <geos/operation/overlay/MinimalEdgeRing.h>
  68 //#include <geos/operation/overlay/MaximalEdgeRing.h>
  69 //#include <geos/operation/overlay/OverlayNodeFactory.h>
  70 //#include <geos/operation/overlay/EdgeSetNoder.h>
  71 //#include <geos/operation/overlay/ElevationMatrix.h>
  72
  73 #endif
  74