Package qupath.lib.roi

Class FastPolygonUnion

java.lang.Object

qupath.lib.roi.FastPolygonUnion

public class FastPolygonUnion
extends Object

Compute a faster union of large numbers of polygons.

This is a sufficiently common requirement, especially with pixel classification, to require its own method.

The algorithm is:

1. Extract all polygons from the input.
2. Identify intersecting and non-intersecting polygons
3. Group all polygons that should potentially be merged, because they intersect (directly or indirectly) with other polygons in the group; each polygon should be represented in only one group
4. Union all the polygon groups
5. Combine all resulting polygons into a single polygon or multipolygon

This partitioning of the problem makes it possible to parallelize checking for intersections and computing the union of groups.

Constructor Summary

Constructors

Constructor	Description
FastPolygonUnion()

Method Summary

Modifier and Type	Method	Description
static Geometry	union(Collection<? extends Geometry> geoms)	Compute a union of all polygons contained in a collection of geometries.
static Geometry	union(Geometry... geoms)	Compute a union of all polygons contained in an array of geometries.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

FastPolygonUnion

public FastPolygonUnion()

Method Details

union

public static Geometry union(Geometry... geoms)

Compute a union of all polygons contained in an array of geometries. Non-polygon geometries will be ignored.

Parameters:

geoms -

Returns:

the union of polygons, or an empty polygon if no geometries are provided

union

public static Geometry union(Collection<? extends Geometry> geoms)

Compute a union of all polygons contained in a collection of geometries. Non-polygon geometries will be ignored.

Parameters:

geoms -

Returns:

the union of polygons, or an empty polygon if no geometries are provided