org.apache.lucene.spatial.util

Class GeoDistanceUtils

java.lang.Object

org.apache.lucene.spatial.util.GeoDistanceUtils

public class GeoDistanceUtils
extends Object

Reusable geo-spatial distance utility methods.

WARNING: This API is experimental and might change in incompatible ways in the next release.

Field Summary

Fields

Modifier and Type	Field and Description
static double	DISTANCE_PCT_ERR error threshold for point-distance queries (in percent) NOTE: Guideline from USGS is 0.005

Method Summary

Methods

Modifier and Type	Method and Description
static void	closestPointOnBBox(double rMinX, double rMinY, double rMaxX, double rMaxY, double lon, double lat, double[] closestPt) Finds the closest point within a rectangle (defined by rMinX, rMinY, rMaxX, rMaxY) to the given (lon, lat) point the result is provided in closestPt.
static double	distanceToDegreesLat(double lat, double distance) Compute the inverse haversine to determine distance in degrees longitude for provided distance in meters
static double	distanceToDegreesLon(double lat, double distance) Compute the inverse haversine to determine distance in degrees longitude for provided distance in meters
static double	haversin(double lat1, double lon1, double lat2, double lon2) Compute the great-circle distance using original haversine implementation published by Sinnot in: R.W.
static double	linearDistance(double[] pt1, double[] pt2) Computes distance between two points in a cartesian (x, y, {z - optional}) coordinate system
static double	maxRadialDistanceMeters(double centerLon, double centerLat) Returns the maximum distance/radius (in meters) from the point 'center' before overlapping
static double	vincentyDistance(double lonA, double latA, double lonB, double latB) Compute the distance between two geo-points using vincenty distance formula Vincenty uses the oblate spheroid whereas haversine uses unit sphere, this will give roughly 22m better accuracy (in worst case) than haversine

Methods inherited from class java.lang.Object

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

Field Detail

DISTANCE_PCT_ERR

public static final double DISTANCE_PCT_ERR

error threshold for point-distance queries (in percent) NOTE: Guideline from USGS is 0.005

See Also:

Constant Field Values

Method Detail

haversin

public static double haversin(double lat1,
              double lon1,
              double lat2,
              double lon2)

Compute the great-circle distance using original haversine implementation published by Sinnot in: R.W. Sinnott, "Virtues of the Haversine", Sky and Telescope, vol. 68, no. 2, 1984, p. 159 NOTE: this differs from SloppyMath.haversin(double, double, double, double) in that it uses the semi-major axis of the earth instead of an approximation based on the average latitude of the two points (which can introduce an additional error up to .337%, or ~67.6 km at the equator)

vincentyDistance

public static final double vincentyDistance(double lonA,
                      double latA,
                      double lonB,
                      double latB)

Compute the distance between two geo-points using vincenty distance formula Vincenty uses the oblate spheroid whereas haversine uses unit sphere, this will give roughly 22m better accuracy (in worst case) than haversine

Parameters:

lonA - longitudinal coordinate of point A (in degrees)

latA - latitudinal coordinate of point A (in degrees)

lonB - longitudinal coordinate of point B (in degrees)

latB - latitudinal coordinate of point B (in degrees)

Returns:

distance (in meters) between point A and point B

linearDistance

public static double linearDistance(double[] pt1,
                    double[] pt2)

Computes distance between two points in a cartesian (x, y, {z - optional}) coordinate system

distanceToDegreesLon

public static double distanceToDegreesLon(double lat,
                          double distance)

Compute the inverse haversine to determine distance in degrees longitude for provided distance in meters

Parameters:

lat - latitude to compute delta degrees lon

distance - distance in meters to convert to degrees lon

Returns:

Sloppy distance in degrees longitude for provided distance in meters

closestPointOnBBox

public static void closestPointOnBBox(double rMinX,
                      double rMinY,
                      double rMaxX,
                      double rMaxY,
                      double lon,
                      double lat,
                      double[] closestPt)

Finds the closest point within a rectangle (defined by rMinX, rMinY, rMaxX, rMaxY) to the given (lon, lat) point the result is provided in closestPt. When the point is outside the rectangle, the closest point is on an edge or corner of the rectangle; else, the closest point is the point itself.

maxRadialDistanceMeters

public static double maxRadialDistanceMeters(double centerLon,
                             double centerLat)

Returns the maximum distance/radius (in meters) from the point 'center' before overlapping

distanceToDegreesLat

public static double distanceToDegreesLat(double lat,
                          double distance)

Compute the inverse haversine to determine distance in degrees longitude for provided distance in meters

Parameters:

lat - latitude to compute delta degrees lon

distance - distance in meters to convert to degrees lon

Returns:

Sloppy distance in degrees longitude for provided distance in meters