gov.usgs.earthquake.nshmp.geo

Class Coordinates

java.lang.Object

gov.usgs.earthquake.nshmp.geo.Coordinates

public class Coordinates
extends Object

Constants and utility methods pertaining to geographic coordinates.

Author:

Peter Powers

Field Summary

Fields

Modifier and Type	Field and Description
static double	EARTH_RADIUS_EQUATORIAL The equatorial radius of the earth as derived from the WGS-84 ellipsoid: 6378.1370 km.
static double	EARTH_RADIUS_MEAN The Authalic mean radius (Ar) of the earth: 6371.0072 km.
static double	EARTH_RADIUS_POLAR The polar radius of the earth as derived from the WGS-84 ellipsoid: 6356.7523 km].
static Range<Double>	LAT_RANGE Supported latitudes: [-90..90]°.
static Range<Double>	LON_RANGE Supported longitudes: (-360..360)°.
static double	MINUTES_PER_DEGREE Constant for arcminutes per degree: 60″.
static double	SECONDS_PER_DEGREE Constant for arcseconds per degree: 3600′.

Constructor Summary

Constructors

Constructor and Description
Coordinates()

Method Summary

Modifier and Type	Method and Description
static double	checkLatitude(double latitude) Ensure that -90° ≤ latitude ≤ 90°.
static double	checkLongitude(double longitude) Ensure that -360° < longitude < 360°.
static double	degreesLatPerKm(Location location) Return a conversion factor for the number of degrees of latitude per km at a given location.
static double	degreesLonPerKm(Location location) Return a conversion factor for the number of degrees of longitude per km at a given location.
static double	minutesToDeg(double minutes) Convert arcminutes to decimal degrees.
static double	radiusAtLocation(Location location) Return the radius of the earth at the latitude of the supplied Location (see Wikipedia for source).
static double	secondsToDeg(double seconds) Convert arcseconds to decimal degrees.
static double	toDecimalDegrees(double degrees, double minutes) Convert degrees and decimal minutes to decimal degrees.

Methods inherited from class java.lang.Object

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

Field Detail

EARTH_RADIUS_MEAN

public static final double EARTH_RADIUS_MEAN

The Authalic mean radius (Ar) of the earth: 6371.0072 km.

See Also:

Wikipedia, Constant Field Values

EARTH_RADIUS_EQUATORIAL

public static final double EARTH_RADIUS_EQUATORIAL

The equatorial radius of the earth as derived from the WGS-84 ellipsoid: 6378.1370 km.

See Also:

Wikipedia, Constant Field Values

EARTH_RADIUS_POLAR

public static final double EARTH_RADIUS_POLAR

The polar radius of the earth as derived from the WGS-84 ellipsoid: 6356.7523 km].

See Also:

Wikipedia, Constant Field Values

LAT_RANGE

public static final Range<Double> LAT_RANGE

Supported latitudes: [-90..90]°.

LON_RANGE

public static final Range<Double> LON_RANGE

Supported longitudes: (-360..360)°.

MINUTES_PER_DEGREE

public static final double MINUTES_PER_DEGREE

Constant for arcminutes per degree: 60″.

See Also:

Constant Field Values

SECONDS_PER_DEGREE

public static final double SECONDS_PER_DEGREE

Constant for arcseconds per degree: 3600′.

See Also:

Constant Field Values

Constructor Detail

Coordinates

public Coordinates()

Method Detail

checkLatitude

public static double checkLatitude(double latitude)

Ensure that -90° ≤ latitude ≤ 90°.

Parameters:

latitude - to validate

Returns:

the validated latitude

Throws:

IllegalArgumentException - if latitude is outside the range [-90..90]°

checkLongitude

public static double checkLongitude(double longitude)

Ensure that -360° < longitude < 360°.

Parameters:

longitude - to validate

Returns:

the validated longitude

Throws:

IllegalArgumentException - if longitude is outside the range (-360..360)°

radiusAtLocation

public static double radiusAtLocation(Location location)

Return the radius of the earth at the latitude of the supplied Location (see Wikipedia for source).

Parameters:

location - at which to compute the earth's radius

Returns:

the earth's radius at the supplied location

degreesLatPerKm

public static double degreesLatPerKm(Location location)

Return a conversion factor for the number of degrees of latitude per km at a given location. This can be used to convert between km-based and degree-based grid spacing. The calculation takes into account the shape of the earth (oblate spheroid) and scales the conversion accordingly.

Parameters:

location - at which to compute conversion value

Returns:

the number of decimal degrees latitude per km at the supplied location

See Also:

radiusAtLocation(Location)

degreesLonPerKm

public static double degreesLonPerKm(Location location)

Return a conversion factor for the number of degrees of longitude per km at a given location. This can be used to convert between km-based and degree-based grid spacing. The calculation scales the degrees longitude per km at the equator by the cosine of the supplied latitude. (Note: The values returned are not based on the radius of curvature of the earth at the supplied location.)

Parameters:

location - at which to compute conversion value

Returns:

the number of decimal degrees longitude per km at the supplied location

secondsToDeg

public static double secondsToDeg(double seconds)

Convert arcseconds to decimal degrees.

Parameters:

seconds - to convert

Returns:

the equivalent number of decimal degrees

minutesToDeg

public static double minutesToDeg(double minutes)

Convert arcminutes to decimal degrees.

Parameters:

minutes - to convert

Returns:

the equivalent number of decimal degrees

toDecimalDegrees

public static double toDecimalDegrees(double degrees,
                                      double minutes)

Convert degrees and decimal minutes to decimal degrees.

Parameters:

degrees - to convert

minutes - to convert

Returns:

the equivalent number of decimal degrees