DiscreteHausdorffDistance class

An algorithm for computing a distance metric which is an approximation to the Hausdorff Distance based on a discretization of the input {@link Geometry}. The algorithm computes the Hausdorff distance restricted to discrete points for one of the geometries. The points can be either the vertices of the geometries (the default), or the geometries with line segments densified by a given fraction. Also determines two points of the Geometries which are separated by the computed distance.

This algorithm is an approximation to the standard Hausdorff distance. Specifically,

   for all geometries a, b:    DHD(a, b) <= HD(a, b)

The approximation can be made as close as needed by densifying the input geometries. In the limit, this value will approach the true Hausdorff distance:

   DHD(A, B, densifyFactor) -> HD(A, B) as densifyFactor -> 0.0

The default approximation is exact or close enough for a large subset of useful cases. Examples of these are:

• computing distance between Linestrings that are roughly parallel to each other, and roughly equal in length. This occurs in matching linear networks.
• Testing similarity of geometries.

An example where the default approximation is not close is:

  A = LINESTRING (0 0, 100 0, 10 100, 10 100)
  B = LINESTRING (0 100, 0 10, 80 10)
DHD(A, B) = 22.360679774997898
HD(A, B) ~= 47.8

Constructors

DiscreteHausdorffDistance(Geometry g0, Geometry g1)

Properties

densifyFrac ↔ double

Value of 0.0 indicates that no densification should take place

getter/setter pair

g0 ↔ Geometry

getter/setter pair

g1 ↔ Geometry

getter/setter pair

hashCode → int

The hash code for this object.

no setter, inherited

ptDist ↔ PointPairDistance

getter/setter pair

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

Methods

compute(Geometry g0, Geometry g1) → void

computeOrientedDistance(Geometry discreteGeom, Geometry geom, PointPairDistance ptDist) → void

distance() → double

getCoordinates() → List<Coordinate>

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

orientedDistance() → double

setDensifyFraction(double densifyFrac) → void

Sets the fraction by which to densify each segment. Each segment will be (virtually) split into a number of equal-length subsegments, whose fraction of the total length is closest to the given fraction.

toString() → String

A string representation of this object.

inherited

Operators

operator ==(Object other) → bool

The equality operator.

inherited

Static Methods

distanceStatic(Geometry g0, Geometry g1) → double

distanceStaticDF(Geometry g0, Geometry g1, double densifyFrac) → double