com.vividsolutions.jts.operation.polygonize

Class Polygonizer


  • public class Polygonizer
extends Object
    Polygonizes a set of Geometrys which contain linework that represents the edges of a planar graph. All types of Geometry are accepted as input; the constituent linework is extracted as the edges to be polygonized. The processed edges must be correctly noded; that is, they must only meet at their endpoints. Polygonization will accept incorrectly noded input but will not form polygons from non-noded edges, and reports them as errors.

    The Polygonizer reports the follow kinds of errors:

    • Dangles - edges which have one or both ends which are not incident on another edge endpoint
    • Cut Edges - edges which are connected at both ends but which do not form part of polygon
    • Invalid Ring Lines - edges which form rings which are invalid (e.g. the component lines contain a self-intersection)
    Polygonization supports extracting only polygons which form a valid polygonal geometry. The set of extracted polygons is guaranteed to be edge-disjoint. This is useful for situations where it is known that the input lines form a valid polygonal geometry.

    • Field Detail

      • graph

        protected com.vividsolutions.jts.operation.polygonize.PolygonizeGraph graph

      • cutEdges

        protected List cutEdges

      • invalidRingLines

        protected List invalidRingLines

      • holeList

        protected List holeList

      • shellList

        protected List shellList

      • polyList

        protected List polyList

    • Constructor Detail

      • Polygonizer

        public Polygonizer()
        Creates a polygonizer with the same GeometryFactory as the input Geometrys. The output mask is #ALL_POLYS.

      • Polygonizer

        public Polygonizer(boolean extractOnlyPolygonal)
        Creates a polygonizer and allow specifyng if only polygons which form a valid polygonal geometry are to be extracted.
        Parameters:
        extractOnlyPolygonal - true if only polygons which form a valid polygonal geometry are to be extracted

    • Method Detail

      • add

        public void add(Collection geomList)
        Adds a collection of geometries to the edges to be polygonized. May be called multiple times. Any dimension of Geometry may be added; the constituent linework will be extracted and used.
        Parameters:
        geomList - a list of Geometrys with linework to be polygonized

      • add

        public void add(Geometry g)
        Add a Geometry to the edges to be polygonized. May be called multiple times. Any dimension of Geometry may be added; the constituent linework will be extracted and used
        Parameters:
        g - a Geometry with linework to be polygonized

      • setCheckRingsValid

        public void setCheckRingsValid(boolean isCheckingRingsValid)
        Allows disabling the valid ring checking, to optimize situations where invalid rings are not expected.

        The default is true

        Parameters:
        isCheckingRingsValid - true if generated rings should be checked for validity

      • getPolygons

        public Collection getPolygons()
        Gets the list of polygons formed by the polygonization.
        Returns:
        a collection of Polygons

      • getGeometry

        public Geometry getGeometry()
        Gets a geometry representing the polygons formed by the polygonization. If a valid polygonal geometry was extracted the result is a geometry.
        Returns:
        a geometry containing the polygons

      • getDangles

        public Collection getDangles()
        Gets the list of dangling lines found during polygonization.
        Returns:
        a collection of the input LineStrings which are dangles

      • getCutEdges

        public Collection getCutEdges()
        Gets the list of cut edges found during polygonization.
        Returns:
        a collection of the input LineStrings which are cut edges

      • getInvalidRingLines

        public Collection getInvalidRingLines()
        Gets the list of lines forming invalid rings found during polygonization.
        Returns:
        a collection of the input LineStrings which form invalid rings