Class CoverageUnion

java.lang.Object
org.locationtech.jts.operation.overlayng.CoverageUnion
public class CoverageUnion extends Object
Unions a valid coverage of polygons or lines in an efficient way.

A valid polygonal coverage is a collection of

invalid reference 
Polygon
s which satisfy the following conditions:
  1. Vector-clean - Line segments within the collection must either be identical or intersect only at endpoints.
  2. Non-overlapping - No two polygons may overlap. Equivalently, polygons must be interior-disjoint.

A valid linear coverage is a collection of

invalid reference 
LineString
s which satisfies the Vector-clean condition. Note that this does not require the LineStrings to be fully noded - i.e. they may contain coincident linework. Coincident line segments are dissolved by the union. Currently linear output is not merged (this may be added in a future release.)

Currently no checking is done to determine whether the input is a valid coverage. This is because coverage validation involves segment intersection detection, which is much more expensive than the union phase. If the input is not a valid coverage then in some cases this will be detected during processing and a

invalid reference 
TopologyException
is thrown. Otherwise, the computation will produce output, but it will be invalid.

Unioning a valid coverage implies that no new vertices are created. This means that a precision model does not need to be specified. The precision of the vertices in the output geometry is not changed.

Author:
Martin Davis
See Also:

  • Method Details

    • union

      public static Geometry union(Geometry coverage)
      Unions a valid polygonal coverage or linear network.
      Parameters:
      coverage - a coverage of polygons or lines
      Returns:
      the union of the coverage