Package ucar.unidata.geoloc

Class Bearing

java.lang.Object

ucar.unidata.geoloc.Bearing

public abstract class Bearing
extends Object

Computes the distance, azimuth, and back azimuth between two lat-lon positions on the Earth's surface. Reference ellipsoid is the WGS-84 by default. You may use a default Earth (EarthEllipsoid.WGS84) or you may define your own using a ucar.unidata.geoloc.Earth object.

Constructor Summary

Constructors

Constructor	Description
Bearing()

Method Summary

Modifier and Type	Method	Description
static Bearing	calculateBearing(double lat1, double lon1, double lat2, double lon2)	Computes distance (in km), azimuth (degrees clockwise positive from North, 0 to 360), and back azimuth (degrees clockwise positive from North, 0 to 360), from latitude-longituide point pt1 to latitude-longituide pt2.
static Bearing	calculateBearing(Earth e, double lat1, double lon1, double lat2, double lon2)	Computes distance (in km), azimuth (degrees clockwise positive from North, 0 to 360), and back azimuth (degrees clockwise positive from North, 0 to 360), from latitude-longituide point pt1 to latitude-longituide pt2.
static Bearing	calculateBearing(Earth e, LatLonPoint pt1, LatLonPoint pt2)	Calculate the bearing between the 2 points.
static Bearing	calculateBearing(LatLonPoint pt1, LatLonPoint pt2)	Calculate the bearing between the 2 points.
static Bearing	create(double azimuth, double backazimuth, double distance)	Create a Bearing object.
static LatLonPoint	findPoint(double lat1, double lon1, double az, double dist)	Calculate a position given an azimuth and distance from another point.
static LatLonPoint	findPoint(Earth e, double lat1, double lon1, double az, double dist)	Calculate a position given an azimuth and distance from another point.
static LatLonPoint	findPoint(Earth e, LatLonPoint pt1, double az, double dist)	Calculate a position given an azimuth and distance from another point.
static LatLonPoint	findPoint(LatLonPoint pt1, double az, double dist)	Calculate a position given an azimuth and distance from another point.
abstract double	getAzimuth()	Get the azimuth in degrees, 0 = north, clockwise positive
abstract double	getBackAzimuth()	Get the back azimuth in degrees, 0 = north, clockwise positive
abstract double	getDistance()	Get the distance in kilometers

Methods inherited from class java.lang.Object

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

Constructor Detail

Bearing

public Bearing()

Method Detail

calculateBearing

public static Bearing calculateBearing(Earth e,
                                       LatLonPoint pt1,
                                       LatLonPoint pt2)

Calculate the bearing between the 2 points. See calculateBearing below.

Parameters:

e - Earth object (defines radius and flattening)

pt1 - Point 1

pt2 - Point 2

Returns:

The bearing

calculateBearing

public static Bearing calculateBearing(LatLonPoint pt1,
                                       LatLonPoint pt2)

Calculate the bearing between the 2 points. See calculateBearing below. Uses default Earth object.

Parameters:

pt1 - Point 1

pt2 - Point 2

Returns:

The bearing

calculateBearing

public static Bearing calculateBearing(double lat1,
                                       double lon1,
                                       double lat2,
                                       double lon2)

Computes distance (in km), azimuth (degrees clockwise positive from North, 0 to 360), and back azimuth (degrees clockwise positive from North, 0 to 360), from latitude-longituide point pt1 to latitude-longituide pt2. Uses default Earth object.

Parameters:

lat1 - Lat of point 1

lon1 - Lon of point 1

lat2 - Lat of point 2

lon2 - Lon of point 2

Returns:

a Bearing object with distance (in km), azimuth from pt1 to pt2 (degrees, 0 = north, clockwise positive)

findPoint

public static LatLonPoint findPoint(Earth e,
                                    LatLonPoint pt1,
                                    double az,
                                    double dist)

Calculate a position given an azimuth and distance from another point.

Parameters:

e - Earth object (defines radius and flattening)

pt1 - Point 1

az - azimuth (degrees)

dist - distance from the point (km)

Returns:

The LatLonPoint

findPoint

public static LatLonPoint findPoint(LatLonPoint pt1,
                                    double az,
                                    double dist)

Calculate a position given an azimuth and distance from another point. Uses default Earth.

Parameters:

pt1 - Point 1

az - azimuth (degrees)

dist - distance from the point (km)

Returns:

The LatLonPoint

findPoint

public static LatLonPoint findPoint(double lat1,
                                    double lon1,
                                    double az,
                                    double dist)

Calculate a position given an azimuth and distance from another point. See details, below. Uses default Earth.

Parameters:

lat1 - latitude of starting point

lon1 - longitude of starting point

az - forward azimuth (degrees)

dist - distance from the point (km)

Returns:

the position as a LatLonPoint

findPoint

public static LatLonPoint findPoint(Earth e,
                                    double lat1,
                                    double lon1,
                                    double az,
                                    double dist)

Calculate a position given an azimuth and distance from another point.

Algorithm from National Geodetic Survey, FORTRAN program "forward," subroutine "DIRCT1," by stephen j. frakes. http://www.ngs.noaa.gov/TOOLS/Inv_Fwd/Inv_Fwd.html

Original documentation:

    SOLUTION OF THE GEODETIC DIRECT PROBLEM AFTER T.VINCENTY
    MODIFIED RAINSFORD'S METHOD WITH HELMERT'S ELLIPTICAL TERMS
    EFFECTIVE IN ANY AZIMUTH AND AT ANY DISTANCE SHORT OF ANTIPODAL
 

Parameters:

e - Earth object (defines radius and flattening)

lat1 - latitude of starting point

lon1 - longitude of starting point

az - forward azimuth (degrees)

dist - distance from the point (km)

Returns:

the position as a LatLonPoint

calculateBearing

public static Bearing calculateBearing(Earth e,
                                       double lat1,
                                       double lon1,
                                       double lat2,
                                       double lon2)

Computes distance (in km), azimuth (degrees clockwise positive from North, 0 to 360), and back azimuth (degrees clockwise positive from North, 0 to 360), from latitude-longituide point pt1 to latitude-longituide pt2.

Algorithm from U.S. National Geodetic Survey, FORTRAN program "inverse," subroutine "INVER1," by L. PFEIFER and JOHN G. GERGEN. See http://www.ngs.noaa.gov/TOOLS/Inv_Fwd/Inv_Fwd.html

Original documentation: SOLUTION OF THE GEODETIC INVERSE PROBLEM AFTER T.VINCENTY MODIFIED RAINSFORD'S METHOD WITH HELMERT'S ELLIPTICAL TERMS EFFECTIVE IN ANY AZIMUTH AND AT ANY DISTANCE SHORT OF ANTIPODAL STANDPOINT/FOREPOINT MUST NOT BE THE GEOGRAPHIC POLE Reference ellipsoid is the WGS-84 ellipsoid. See http://www.colorado.edu/geography/gcraft/notes/datum/elist.html

Parameters:

e - Earth object (defines radius and flattening)

lat1 - Lat of point 1

lon1 - Lon of point 1

lat2 - Lat of point 2

lon2 - Lon of point 2

Returns:

a Bearing object with distance (in km), azimuth from pt1 to pt2 (degrees, 0 = north, clockwise positive)

create

public static Bearing create(double azimuth,
                             double backazimuth,
                             double distance)

Create a Bearing object.

Parameters:

azimuth - the azimuth, degrees, 0 = north, clockwise positive

backazimuth - the back azimuth, degrees, 0 = north, clockwise positive

distance - separation in kilometers

getAzimuth

public abstract double getAzimuth()

Get the azimuth in degrees, 0 = north, clockwise positive

getBackAzimuth

public abstract double getBackAzimuth()

Get the back azimuth in degrees, 0 = north, clockwise positive

getDistance

public abstract double getDistance()

Get the distance in kilometers