Class IndexedFacetDistance

Hierarchy: Object , IndexedFacetDistance

public class IndexedFacetDistance

Computes the distance between the facets (segments and vertices) of two Geometrys using a Branch-and-Bound algorithm. The Branch-and-Bound algorithm operates over a traversal of R-trees built on the target and the query geometries.

This approach provides the following benefits:

Performance is dramatically improved due to the use of the R-tree index and the pruning due to the Branch-and-Bound approach
The spatial index on the target geometry is cached which allow reuse in an repeated query situation.

Using this technique is usually much more performant than using the brute-force Geometry.distance(Geometry) when one or both input geometries are large, or when evaluating many distance computations against a single geometry.

This class is thread-safe.

Authors:: Martin Davis

public IndexedFacetDistance(Geometry geom)

Creates a new distance-finding instance for a given target Geometry.

Distances will be computed to all facets of the input geometry. The facets of the geometry are the discrete segments and points contained in its components. In the case of Lineal and Puntal inputs, this is equivalent to computing the conventional distance. In the case of Polygonal inputs, this is equivalent to computing the distance to the polygon boundaries.

Parameters:: geom - geom a Geometry, which may be of any type.

public static double distance(Geometry g1, Geometry g2)

Computes the distance between facets of two geometries.

For geometries with many segments or points, this can be faster than using a simple distance algorithm.

Parameters:: g1 - g1 a geometry; g2 - g2 a geometry

Returns:: the distance between facets of the geometries

public static boolean isWithinDistance(Geometry g1, Geometry g2, double distance)

Tests whether the facets of two geometries lie within a given distance.

Parameters:: g1 - g1 a geometry; g2 - g2 a geometry; distance - distance the distance limit

Returns:: true if two facets lie with the given distance

public static Coordinate[] nearestPoints(Geometry g1, Geometry g2)

Computes the nearest points of the facets of two geometries.

Parameters:: g1 - g1 a geometry; g2 - g2 a geometry

Returns:: the nearest points on the facets of the geometries

public double distance(Geometry g)

Computes the distance from the base geometry to the given geometry.

Parameters:: g - g the geometry to compute the distance to

Returns:: the computed distance

public GeometryLocation[] nearestLocations(Geometry g)

Computes the nearest locations on the base geometry and the given geometry.

Parameters:: g - g the geometry to compute the nearest location to

Returns:: the nearest locations

public Coordinate[] nearestPoints(Geometry g)

Compute the nearest locations on the target geometry and the given geometry.

Parameters:: g - g the geometry to compute the nearest point to

Returns:: the nearest points

public boolean isWithinDistance(Geometry g, double maxDistance)

Tests whether the base geometry lies within a specified distance of the given geometry.

Parameters:: g - g the geometry to test; maxDistance - maxDistance the maximum distance to test

Returns:: true if the geometry lies with the specified distance