/*
* Copyright 1998-2014 University Corporation for Atmospheric Research/Unidata
*
* Portions of this software were developed by the Unidata Program at the
* University Corporation for Atmospheric Research.
*
* Access and use of this software shall impose the following obligations
* and understandings on the user. The user is granted the right, without
* any fee or cost, to use, copy, modify, alter, enhance and distribute
* this software, and any derivative works thereof, and its supporting
* documentation for any purpose whatsoever, provided that this entire
* notice appears in all copies of the software, derivative works and
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*
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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*/
package ucar.unidata.geoloc;
import net.jcip.annotations.Immutable;
import java.io.Serializable;
import java.util.Formatter;
/**
* Defines the shape of the earth ellipsoid.
*
* @author Russ Rew
*/
@Immutable
public class Earth implements Serializable {
public static final Earth DEFAULT = new Earth();
private static final double earthRadius = 6371229.; // canonical radius of the spherical earth in meters "WGS 84"
/**
* Get canonical radius of spherical earth, in meters
*
* @return canonical radius of spherical earth in meters
*/
public static double getRadius() {
return earthRadius;
}
///////////////////////////////////////////////////////////////////////////////////
protected final double eccentricity; // eccentricity
protected final double eccentricitySquared; // eccentricity squared
protected final double equatorRadius; // equatorial radius (semimajor axis)
protected final double poleRadius; // polar radius (semiminor axis)
protected final double flattening; // flattening
protected final String name;
/**
* Spherical earth with canonical radius.
*/
public Earth() {
this(earthRadius);
}
/**
* Create a spherical earth.
*
* @param radius radius of spherical earth.
*/
public Earth(double radius) {
this.equatorRadius = radius;
this.poleRadius = radius;
this.flattening = 0.0;
this.eccentricity = 1.0;
this.eccentricitySquared = 1.0;
this.name = "spherical_earth";
}
/**
* Create an ellipsoidal earth.
* The reciprocalFlattening is used if not zero, else the poleRadius is used.
*
* @param equatorRadius equatorial radius (semimajor axis) in meters, must be specified
* @param poleRadius polar radius (semiminor axis) in meters
* @param reciprocalFlattening inverse flattening = 1/flattening = a / (a-b)
*/
public Earth(double equatorRadius, double poleRadius, double reciprocalFlattening) {
this(equatorRadius, poleRadius, reciprocalFlattening, "ellipsoidal_earth");
}
/**
* Create an ellipsoidal earth with a name.
*
* @param equatorRadius equatorial radius (semimajor axis) in meters, must be specified
* @param poleRadius polar radius (semiminor axis) in meters; if reciprocalFlattening != 0 then this is ignored
* @param reciprocalFlattening inverse flattening = 1/flattening = a / (a-b); if 0 use the poleRadius to calculate
* @param name name of the Earth
*/
public Earth(double equatorRadius, double poleRadius, double reciprocalFlattening, String name) {
this.equatorRadius = equatorRadius;
this.name = name;
if (reciprocalFlattening != 0) {
flattening = 1.0 / reciprocalFlattening;
eccentricitySquared = 2 * flattening - flattening * flattening;
this.poleRadius = equatorRadius * Math.sqrt(1.0 - eccentricitySquared);
} else {
this.poleRadius = poleRadius;
eccentricitySquared = 1.0 - (poleRadius * poleRadius) / (equatorRadius * equatorRadius);
flattening = 1.0 - poleRadius / equatorRadius;
}
eccentricity = Math.sqrt(eccentricitySquared);
}
public boolean isSpherical() {
return flattening == 0.0;
}
/**
* Specify earth with equatorial and polar radius.
*
* @param a semimajor (equatorial) radius, in meters.
* @param b semiminor (polar) radius, in meters.
*
* Earth(double a, double b) {
* this.equatorRadius = a;
* this.poleRadius = b;
* eccentricitySquared = 1.0 - (b * b) / (a * a);
* flattening = 1.0 - b / a;
* }
*
*
* Specify earth with semimajor radius a, and flattening f.
* b = a(1-flattening)
*
* @param a semimajor (equatorial) radius, in meters.
* @param f flattening.
* @param fake fake
*
* Earth(double a, double f, boolean fake) {
* this.equatorRadius = a;
* this.flattening = flattening;
* poleRadius = a * (1.0 - flattening);
* eccentricitySquared = 1.0 - (poleRadius * poleRadius) / (a * a);
* }
*
* @return _more_
*/
/**
* Get the equatorial radius (semimajor axis) of the earth, in meters.
*
* @return equatorial radius (semimajor axis) in meters
*/
public double getMajor() {
return equatorRadius;
}
/**
* Get the polar radius (semiminor axis) of the earth, in meters.
*
* @return polar radius (semiminor axis) in meters
*/
public double getMinor() {
return poleRadius;
}
/**
* Get the Name property.
*
* @return The Name
*/
public String getName() {
return name;
}
/**
* Get the Eccentricity property.
*
* @return The Eccentricity
*/
public double getEccentricity() {
return eccentricity;
}
/**
* Get the EccentricitySquared property.
*
* @return The EccentricitySquared
*/
public double getEccentricitySquared() {
return eccentricitySquared;
}
/**
* Get the EquatorRadius property.
*
* @return The EquatorRadius
*/
public double getEquatorRadius() {
return equatorRadius;
}
/**
* Get the PoleRadius property.
*
* @return The PoleRadius
*/
public double getPoleRadius() {
return poleRadius;
}
/**
* Get the Flattening property.
*
* @return The Flattening
*/
public double getFlattening() {
return flattening;
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Earth earth = (Earth) o;
if (Double.compare(earth.equatorRadius, equatorRadius) != 0) return false;
if (Double.compare(earth.poleRadius, poleRadius) != 0) return false;
// if (name != null ? !name.equals(earth.name) : earth.name != null) return false;
return true;
}
@Override
public int hashCode() {
int result;
long temp;
temp = equatorRadius != +0.0d ? Double.doubleToLongBits(equatorRadius) : 0L;
result = (int) (temp ^ (temp >>> 32));
temp = poleRadius != +0.0d ? Double.doubleToLongBits(poleRadius) : 0L;
result = 31 * result + (int) (temp ^ (temp >>> 32));
result = 31 * result + (name != null ? name.hashCode() : 0);
return result;
}
@Override
public String toString() {
Formatter ff = new Formatter();
ff.format("equatorRadius=%f inverseFlattening=%f", equatorRadius,
(1.0 / flattening));
return ff.toString();
}
}