com.revolsys.jts.operation.distance

Class IndexedFacetDistance

java.lang.Object

com.revolsys.jts.operation.distance.IndexedFacetDistance

public class IndexedFacetDistance
extends Object

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 possibly also the query geometries.

This approach provides the following benefits:

• Performance is improved due to the effects of the R-tree index and the pruning due to the Branch-and-Bound approach
• The spatial index on the target geometry can be cached to allow reuse in an incremental query situation.

Using this technique can be much more performant than using getDistance(Geometry) when one or both input geometries are large, or when evaluating many distance computations against a single geometry.

This class is not thread-safe.

Author:

Martin Davis

Constructor Summary

Constructors

Constructor and Description
IndexedFacetDistance(Geometry g1) Creates a new distance-finding instance for a given target Geometry.

Method Summary

Methods

Modifier and Type	Method and Description
static double	distance(Geometry g1, Geometry g2) Computes the distance between two geometries using the indexed approach.
double	getDistance(Geometry g) Computes the distance from the base geometry to the given geometry.

Methods inherited from class java.lang.Object

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

Constructor Detail

IndexedFacetDistance

public IndexedFacetDistance(Geometry g1)

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 polygons boundaries.

Parameters:

g1 - a Geometry, which may be of any type.

Method Detail

distance

public static double distance(Geometry g1,
              Geometry g2)

Computes the distance between two geometries using the indexed approach.

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

Parameters:

g1 - a geometry

g2 - a geometry

Returns:

the distance between the two geometries

getDistance

public double getDistance(Geometry g)

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

Parameters:

g - the geometry to compute the distance to

Returns:

the computed distance