org.onebusaway.geospatial.services
Class SphericalGeometryLibrary

java.lang.Object
  org.onebusaway.geospatial.services.SphericalGeometryLibrary

public class SphericalGeometryLibrary
extends Object

Field Summary

static double	COS_MAX_LAT
static double	METERS_PER_DEGREE_AT_EQUATOR
static double	RADIUS_OF_EARTH_IN_KM

Constructor Summary

SphericalGeometryLibrary()

Method Summary

static CoordinateBounds	bounds(CoordinateBounds b, double distance)
static CoordinateBounds	bounds(CoordinatePoint point, double distance)
static CoordinateBounds	bounds(double lat, double lon, double distance)
static CoordinateBounds	bounds(double lat, double lon, double latDistance, double lonDistance)
static CoordinateBounds	boundsFromLatLonOffset(double lat, double lon, double latOffset, double lonOffset)
static CoordinateBounds	boundsFromLatLonSpan(double lat, double lon, double latSpan, double lonSpan)
static double	distance(CoordinatePoint a, CoordinatePoint b)
static double	distance(double lat1, double lon1, double lat2, double lon2)
static double	distance(double lat1, double lon1, double lat2, double lon2, double radius)
static double	distanceFaster(double lat1, double lon1, double lat2, double lon2) This method is fast but not very accurate
static CoordinatePoint	getCenterOfBounds(CoordinateBounds b)
static double	getOrientation(double latFrom, double lonFrom, double latTo, double lonTo) If Wikipedia is to be trusted, then: http://en.wikipedia.org/wiki/Spherical_law_of_cosines claims that the standard ordinary planar law of cosines is a reasonable approximation for the more-complex spherical law of cosines when the central angles of the spherical triangle are small.
static CoordinatePoint	projectPointToSegmentAppropximate(CoordinatePoint point, CoordinatePoint segmentStart, CoordinatePoint segmentEnd) Note that this is an approximate method at best that will perform increasingly worse as the distance between the points increases.

Methods inherited from class java.lang.Object

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

Field Detail

RADIUS_OF_EARTH_IN_KM

public static final double RADIUS_OF_EARTH_IN_KM

See Also:

Constant Field Values

COS_MAX_LAT

public static final double COS_MAX_LAT

METERS_PER_DEGREE_AT_EQUATOR

public static final double METERS_PER_DEGREE_AT_EQUATOR

See Also:

Constant Field Values

Constructor Detail

SphericalGeometryLibrary

public SphericalGeometryLibrary()

Method Detail

distanceFaster

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

This method is fast but not very accurate

Parameters:

lat1 -

lon1 -

lat2 -

lon2 -

Returns:

distance

public static final double distance(double lat1,
                                    double lon1,
                                    double lat2,
                                    double lon2)

distance

public static final double distance(CoordinatePoint a,
                                    CoordinatePoint b)

distance

public static final double distance(double lat1,
                                    double lon1,
                                    double lat2,
                                    double lon2,
                                    double radius)

bounds

public static final CoordinateBounds bounds(CoordinatePoint point,
                                            double distance)

bounds

public static CoordinateBounds bounds(CoordinateBounds b,
                                      double distance)

bounds

public static final CoordinateBounds bounds(double lat,
                                            double lon,
                                            double distance)

bounds

public static final CoordinateBounds bounds(double lat,
                                            double lon,
                                            double latDistance,
                                            double lonDistance)

boundsFromLatLonOffset

public static final CoordinateBounds boundsFromLatLonOffset(double lat,
                                                            double lon,
                                                            double latOffset,
                                                            double lonOffset)

Parameters:

lat -

lon -

latOffset -

lonOffset -

Returns:

CoordinateBounds(lat-latOffser,lon-lonOffset,lat+latOffset,lon+lonOffset )

boundsFromLatLonSpan

public static final CoordinateBounds boundsFromLatLonSpan(double lat,
                                                          double lon,
                                                          double latSpan,
                                                          double lonSpan)

getCenterOfBounds

public static CoordinatePoint getCenterOfBounds(CoordinateBounds b)

getOrientation

public static double getOrientation(double latFrom,
                                    double lonFrom,
                                    double latTo,
                                    double lonTo)

If Wikipedia is to be trusted, then: http://en.wikipedia.org/wiki/Spherical_law_of_cosines claims that the standard ordinary planar law of cosines is a reasonable approximation for the more-complex spherical law of cosines when the central angles of the spherical triangle are small.

Parameters:

latFrom -

lonFrom -

latTo -

lonTo -

Returns:

the orientation angle in degrees, 0º is East, 90º is North, 180º is West, and 270º is South

projectPointToSegmentAppropximate

public static CoordinatePoint projectPointToSegmentAppropximate(CoordinatePoint point,
                                                                CoordinatePoint segmentStart,
                                                                CoordinatePoint segmentEnd)

Note that this is an approximate method at best that will perform increasingly worse as the distance between the points increases.

Parameters:

point -

segmentStart -

segmentEnd -

Returns: