/**
*
*/
package vroom.common.utilities;
/**
* The class <code>GeoTools</code> provides utility methods to calculate distances using different coordinate systems.
* <p>
* Creation date: Mar 22, 2012 - 1:05:13 PM
*
* @author Victor Pillac, <a href="http://uniandes.edu.co">Universidad de Los Andes</a>-<a
* href="http://copa.uniandes.edu.co">Copa</a> <a href="http://www.emn.fr">Ecole des Mines de Nantes</a>-<a
* href="http://www.irccyn.ec-nantes.fr/irccyn/d/en/equipes/Slp">SLP</a>
* @version 1.0
*/
public class GeoTools {
public static enum CoordinateSytem {
CARTESIAN, POLAR, LAT_LON_DEC_DEG
};
/** The mean earth radius in kilometers */
public static final double EARTH_RADIUS_KM = 6371.009;
/** The mean earth radius in meters */
public static final double EARTH_RADIUS_M = 6371009;
/**
* Returns the euclidean distance between two points
*
* @param x1
* the x coordinate of the first point
* @param y1
* the y coordinate of the first point
* @param x2
* the x coordinate of the second point
* @param y2
* the y coordinate of the second point
* @return the distance between points {@code (x1,y1)} and {@code (x2,y2)}
*/
public static double distEuclidean(double x1, double y1, double x2, double y2) {
return Math.sqrt(Math.pow(x1 - x2, 2) + Math.pow(y1 - y2, 2));
}
/**
* Calculates geodetic distance between two points specified by latitude/longitude using Haversine formula
*
* @param lat1
* first point latitude in decimal degrees
* @param lon1
* first point longitude in decimal degrees
* @param lat2
* second point latitude in decimal degrees
* @param lon2
* second point longitude in decimal degrees
* @returns distance in meters between points with 0.3% precision
*/
public static double distHaversine(double lat1, double lon1, double lat2, double lon2) {
double dLat = Math.toRadians(lat2 - lat1);
double dLon = Math.toRadians(lon2 - lon1);
lat1 = Math.toRadians(lat1);
lat2 = Math.toRadians(lat2);
double sindLat = Math.sin(dLat / 2);
double sindLon = Math.sin(dLon / 2);
double a = Math.pow(sindLat, 2) + Math.pow(sindLon, 2) * Math.cos(lat1) * Math.cos(lat2);
double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
return EARTH_RADIUS_M * c;
}
/**
* Calculates geodetic distance between two points specified by latitude/longitude using Vincenty inverse formula
* for ellipsoids
*
* @param lat1
* first point latitude in decimal degrees
* @param lon1
* first point longitude in decimal degrees
* @param lat2
* second point latitude in decimal degrees
* @param lon2
* second point longitude in decimal degrees
* @returns distance in meters between points with 5.10<sup>-4</sup> precision
* @see <a href="http://www.movable-type.co.uk/scripts/latlong-vincenty.html">Originally posted here</a>
*/
public static double distVincenty(double lat1, double lon1, double lat2, double lon2) {
double a = 6378137, b = 6356752.314245, f = 1 / 298.257223563; // WGS-84 ellipsoid params
double L = Math.toRadians(lon2 - lon1);
double U1 = Math.atan((1 - f) * Math.tan(Math.toRadians(lat1)));
double U2 = Math.atan((1 - f) * Math.tan(Math.toRadians(lat2)));
double sinU1 = Math.sin(U1), cosU1 = Math.cos(U1);
double sinU2 = Math.sin(U2), cosU2 = Math.cos(U2);
double sinLambda, cosLambda, sinSigma, cosSigma, sigma, sinAlpha, cosSqAlpha, cos2SigmaM;
double lambda = L, lambdaP, iterLimit = 100;
do {
sinLambda = Math.sin(lambda);
cosLambda = Math.cos(lambda);
sinSigma = Math.sqrt((cosU2 * sinLambda) * (cosU2 * sinLambda)
+ (cosU1 * sinU2 - sinU1 * cosU2 * cosLambda) * (cosU1 * sinU2 - sinU1 * cosU2 * cosLambda));
if (sinSigma == 0)
return 0; // co-incident points
cosSigma = sinU1 * sinU2 + cosU1 * cosU2 * cosLambda;
sigma = Math.atan2(sinSigma, cosSigma);
sinAlpha = cosU1 * cosU2 * sinLambda / sinSigma;
cosSqAlpha = 1 - sinAlpha * sinAlpha;
cos2SigmaM = cosSigma - 2 * sinU1 * sinU2 / cosSqAlpha;
if (Double.isNaN(cos2SigmaM))
cos2SigmaM = 0; // equatorial line: cosSqAlpha=0 (ยง6)
double C = f / 16 * cosSqAlpha * (4 + f * (4 - 3 * cosSqAlpha));
lambdaP = lambda;
lambda = L + (1 - C) * f * sinAlpha
* (sigma + C * sinSigma * (cos2SigmaM + C * cosSigma * (-1 + 2 * cos2SigmaM * cos2SigmaM)));
} while (Math.abs(lambda - lambdaP) > 1e-12 && --iterLimit > 0);
if (iterLimit == 0)
return Double.NaN; // formula failed to converge
double uSq = cosSqAlpha * (a * a - b * b) / (b * b);
double A = 1 + uSq / 16384 * (4096 + uSq * (-768 + uSq * (320 - 175 * uSq)));
double B = uSq / 1024 * (256 + uSq * (-128 + uSq * (74 - 47 * uSq)));
double deltaSigma = B
* sinSigma
* (cos2SigmaM + B
/ 4
* (cosSigma * (-1 + 2 * cos2SigmaM * cos2SigmaM) - B / 6 * cos2SigmaM
* (-3 + 4 * sinSigma * sinSigma) * (-3 + 4 * cos2SigmaM * cos2SigmaM)));
double dist = b * A * (sigma - deltaSigma);
return dist;
}
public static void main(String[] args) {
double lat1 = 39.021911;
double lon1 = -104.397891;
double lat2 = 39.021385;
double lon2 = -104.396826;
System.out.println(distHaversine(lat1, lon1, lat2, lon2));
System.out.println(distVincenty(lat1, lon1, lat2, lon2));
}
}