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Coordinate Transformation Suite (abridged CTS) is a library developed to perform coordinate
transformations using well known geodetic algorithms and parameter sets. It strives to be simple, flexible and
interoperable, in this order.
/*
* Coordinate Transformations Suite (abridged CTS) is a library developped to
* perform Coordinate Transformations using well known geodetic algorithms
* and parameter sets.
* Its main focus are simplicity, flexibility, interoperability, in this order.
*
* This library has been originally developed by Michaël Michaud under the JGeod
* name. It has been renamed CTS in 2009 and shared to the community from
* the OrbisGIS code repository.
*
* CTS is free software: you can redistribute it and/or modify it under the
* terms of the GNU Lesser General Public License as published by the Free Software
* Foundation, either version 3 of the License.
*
* CTS is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
* A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License along with
* CTS. If not, see Transform geographic coordinates (latitude, longitude, ellipsoidal height
* into geocentric coordinates.
* Geographic coordinates and geocentric coordinates are supposed to use the
* same reference datum and to be standardized :
*
* - Geographic coordinates are given in the following order : latitude
* (radians), longitude (radians from Greenwich) and optionnaly ellipsoidal
* height (default = 0.0).
* - The center of the geocentric system (center of the mass) is equal to the
* geographic coordinates reference ellipsoid.
*
- Z axis is oriented from origin to North Pole
* - Y axis is oriented from origin to intersection of equator and Greenwich
* Meridian
* - OXYZ is direct
* - Units = radian, meter (to facilitate transformation operations).
*
*
* @author Michaël Michaud
*/
public class Geocentric2Geographic extends AbstractCoordinateOperation {
/**
* The Identifier used for all Geocentric to geographic conversions.
*/
private static final Identifier opId =
new Identifier("EPSG", "9602",
"Geocentric to geographic conversion", "Geocentric to geographic");
/**
* The ellipsoid used to define geographic coordinates.
*/
private Ellipsoid ellipsoid;
/**
* Stop condition for the Geocentric to Geographic transformation algorithm.
* epsilon is a value in radian, 1E-11 is the default epsilon and it means
* that error is less than 1E-4 m.
*/
private double epsilon;
/**
* Create a new Geographic2Geocentric transformation for a specific
* ellipsoid. The reference datum for both geographic and geocentric
* coordinates is the same.
*
* @param ellipsoid the ellipsoid used to define geographic coordinates
*/
public Geocentric2Geographic(Ellipsoid ellipsoid) {
super(opId);
this.ellipsoid = ellipsoid;
this.precision = 1E-4; // 0.0001 mm
this.epsilon = 1E-11; // condition d'arret = 1E-11 radian < 1E-4 m
}
/**
* Create a new Geographic2Geocentric transformation for a specific
* ellipsoid. The reference datum for both geographic and geocentric
* coordinates is the same.
*
* @param ellipsoid the ellipsoid used to define geographic coordinates
* @param epsilon stop condition for the Geocentric to Geographic
* transformation algorithm (epsilon is a value in radian, 1E-11 is the
* default epsilon and it means that error is less than 1E-4 m)
*/
public Geocentric2Geographic(Ellipsoid ellipsoid, double epsilon) {
super(opId);
this.ellipsoid = ellipsoid;
this.precision = 1E-4; // 0.0001 mm
this.epsilon = epsilon; // condition d'arret = 1E-11 radian < 1E-4 m
}
/**
* Return coordinates representing the same point in a standard
* geocentric coordinate system.
*
* @param coord is an array containing 2 or 3 double representing geographic
* coordinates in the following order : latitude (radians), longitude
* (radians from Greenwich) and optionnaly ellipsoidal height (if coord
* contains only 2 double's, height is set to 0).
* @throws IllegalCoordinateException if coord is not
* compatible with this CoordinateOperation.
*/
@Override
public double[] transform(double[] coord)
throws IllegalCoordinateException {
if (coord.length < 3) {
throw new CoordinateDimensionException(coord, 3);
}
double X = coord[0];
double Y = coord[1];
double Z = coord[2];
double a = ellipsoid.getSemiMajorAxis();
double e2 = ellipsoid.getSquareEccentricity();
// Calcul de la longitude
double lon = atan2(Y, X);
// Calcul de la latitude
double XY2 = sqrt(X * X + Y * Y);
double lat0 = atan(Z / (XY2 * (1 - (a * e2 / sqrt(X * X + Y * Y + Z * Z)))));
double lati = lat0;
double lati1 = 0;
while (abs(lati1 - lati) > epsilon) {
lati = lati1;
double exp1 = a * e2 * cos(lati);
double exp2 = sqrt(1 - (e2 * sin(lati) * sin(lati)));
lati1 = atan((Z / XY2) / (1 - (exp1 / (XY2 * exp2))));
}
double lat = lati1;
// Calcul de la hauteur
double height = XY2 / cos(lat) - a / sqrt(1 - (e2 * sin(lat) * sin(lat)));
coord[0] = lat;
coord[1] = lon;
coord[2] = height;
return coord;
}
/**
* Creates the inverse CoordinateOperation.
*/
@Override
public CoordinateOperation inverse() throws NonInvertibleOperationException {
return new Geographic2Geocentric(ellipsoid);
}
/**
* Return a String representation of this Geographic/Geocentric converter.
*/
@Override
public String toString() {
return getName() + " (" + ellipsoid.getName() + ")";
}
public Ellipsoid getEllipsoid() {
return ellipsoid;
}
/**
* Returns true if object is equals to
* this. Tests equality between the ellipsoid used by the
* transformation.
*
* @param object The object to compare this Geocentric2Geographic against
*/
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (o instanceof Geocentric2Geographic) {
Geocentric2Geographic gc2gg = (Geocentric2Geographic) o;
return getEllipsoid().equals(gc2gg.getEllipsoid());
}
return false;
}
/**
* Returns the hash code for this Geocentric2Geographic.
*/
@Override
public int hashCode() {
int hash = 5;
hash = 89 * hash + (this.ellipsoid != null ? this.ellipsoid.hashCode() : 0);
return hash;
}
}