Namespace NetTopologySuite.Operation.Union

Classes

CascadedPolygonUnion

Provides an efficient method of unioning a collection of IPolygonal geometries. The geometries are indexed using a spatial index, and unioned recursively in index order. For geometries with a high degree of overlap, this has the effect of reducing the number of vertices early in the process, which increases speed and robustness.

This algorithm is faster and more robust than the simple iterated approach of repeatedly unioning each polygon to a result geometry.

OverlapUnion

Unions MultiPolygons efficiently by using full topological union only for polygons which may overlap, and combining with the remaining polygons. Polygons which may overlap are those which intersect the common extent of the inputs. Polygons wholly outside this extent must be disjoint to the computed union. They can thus be simply combined with the union result, which is much more performant. (There is one caveat to this, which is discussed below).

This situation is likely to occur during cascaded polygon union, since the partitioning of polygons is done heuristically and thus may group disjoint polygons which can lie far apart. It may also occur in real world data which contains many disjoint polygons (e.g. polygons representing parcels on different street blocks).

PointGeometryUnion

UnaryUnionOp

Unions a Collection of Geometrys or a single Geometry (which may be a GeometryCollection) together.

UnionInteracting

Experimental code to union MultiPolygons with processing limited to the elements which actually interact.

UnionStrategy

An strategy class that allows UnaryUnion to adapt to different kinds of overlay algorithms.