Class DiscreteHausdorffDistance
java.lang.Object
org.locationtech.jts.algorithm.distance.DiscreteHausdorffDistance
An algorithm for computing a distance metric
which is an approximation to the Hausdorff Distance
based on a discretization of the input
Geometry
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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 -> 0.0The 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.
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
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Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionstatic class
static class
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Field Summary
FieldsModifier and TypeFieldDescriptionprivate double
Value of 0.0 indicates that no densification should take placeprivate Geometry
private Geometry
private PointPairDistance
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionprivate void
private void
computeOrientedDistance
(Geometry discreteGeom, Geometry geom, PointPairDistance ptDist) double
distance()
static double
static double
double
void
setDensifyFraction
(double densifyFrac) Sets the fraction by which to densify each segment.
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Field Details
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g0
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g1
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ptDist
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densifyFrac
private double densifyFracValue of 0.0 indicates that no densification should take place
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Constructor Details
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DiscreteHausdorffDistance
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Method Details
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distance
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distance
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setDensifyFraction
public void setDensifyFraction(double densifyFrac) 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.- Parameters:
densifyFrac
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distance
public double distance() -
orientedDistance
public double orientedDistance() -
getCoordinates
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compute
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computeOrientedDistance
private void computeOrientedDistance(Geometry discreteGeom, Geometry geom, PointPairDistance ptDist)
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