org.wamblee.gps.geometry.Wgs84CoordinateSystem Maven / Gradle / Ivy
/*
* Copyright 2006 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.wamblee.gps.geometry;
import static java.lang.Math.PI;
import static java.lang.Math.cos;
import static java.lang.Math.sin;
/**
* Represents the WGS 84 coordinate system for a GPS measurement identified by
*
* - x1: latitude in degrees
* - x2: longitude in degrees
* - x3: elevation in meters
*
* WGS84 models the earth as an ellipse.
*
* @author Erik Brakkee
*/
public class Wgs84CoordinateSystem implements CoordinateSystem {
/*
* Ellipsoide parameters, where the ellipsoide is defined by
*
* (x^2 + y^2)/a^2 + z^2/b^2 = 1
*/
/**
* The radius of the ellipse at the equator
*/
private static final double A = 6378137.000;
/**
* The distance of the North and South poles to the center of the ellipsoide.
*/
private static final double B = 6356752.314;
/* (non-Javadoc)
* @see org.wamblee.gpx.CoordinateSystem#toReferenceSystem(org.wamblee.gpx.Coordinates)
*/
public Coordinates toReferenceSystem(Coordinates aCoordinates) {
double latrad = radians(aCoordinates.getX1());
double lonrad = radians(aCoordinates.getX2());
double coslat = cos(latrad);
double sinlat = sin(latrad);
double coslon = cos(lonrad);
double sinlon = sin(lonrad);
double r = A*B/Math.sqrt(B*B*coslat*coslat + A*A*sinlat*sinlat) + aCoordinates.getX3();
return new Coordinates(r*coslat*coslon,
r*coslat*sinlon,
r*sinlat);
}
private double radians(double aDegrees) {
return aDegrees/180.0*PI;
}
}