tim@185: package de.intevation.gnv.utils;
tim@185:
sascha@779: import com.vividsolutions.jts.geom.Coordinate;
tim@185: import com.vividsolutions.jts.geom.Point;
sascha@362:
sascha@362: import java.util.List;
tim@185:
tim@185: /**
ingo@806: * A helper class to calculate distances between points and coordinates.
sascha@807: *
sascha@780: * @author Tim Englich
tim@185: *
tim@185: */
tim@185: public class DistanceCalculator {
tim@185:
tim@185: private final static double flattening = 1.0 / 298.257233563;
sascha@778:
tim@185: private final static double earthRadius = 6378137.0 / 1000.0 ;
sascha@778:
tim@185: /**
tim@185: * Constructor
tim@185: */
tim@185: public DistanceCalculator() {
tim@185: }
sascha@778:
ingo@806:
ingo@806: /**
ingo@806: * Calculates the distance between two points.
ingo@806: *
ingo@806: * @param p1 First point.
ingo@806: * @param p2 Second point.
ingo@806: * @return the distance.
ingo@806: */
ingo@296: public static double calculateDistance(Point p1, Point p2){
sascha@362: return calculateDistance(p1.getCoordinate(), p2.getCoordinate());
sascha@362: }
sascha@362:
ingo@806:
ingo@806: /**
ingo@806: * Calculates the distance between two coordinates.
ingo@806: *
ingo@806: * @param p1 First coordinate.
ingo@806: * @param p2 Second coordinate.
ingo@806: * @return the distance.
ingo@806: */
sascha@362: public static double calculateDistance(Coordinate p1, Coordinate p2){
tim@185: double resultValue = 0.0;
sascha@778:
sascha@362: double b1 = p1.y;
sascha@362: double b2 = p2.y;
sascha@778:
sascha@362: double l1 = p1.x;
sascha@362: double l2 = p2.x;
sascha@778:
sascha@778:
tim@185: double F = (b1 + b2) / 2.0;
tim@185: double G = (b1 - b2) / 2.0;
tim@185: double l = (l1 - l2) / 2.0;
sascha@778:
tim@185: F = (Math.PI / 180.0) * F;
tim@185: G = (Math.PI / 180.0) * G;
tim@185: l = (Math.PI / 180.0) * l;
sascha@778:
tim@185: double S = ((Math.sin(G) * Math.sin(G)) * ((Math.cos(l) * Math.cos(l))))+
tim@185: ((Math.cos(F) * Math.cos(F)) * ((Math.sin(l) * Math.sin(l))));
sascha@778:
tim@185: double C = ((Math.cos(G) * Math.cos(G)) * ((Math.cos(l) * Math.cos(l))))+
tim@185: ((Math.sin(F) * Math.sin(F)) * ((Math.sin(l) * Math.sin(l))));
sascha@778:
tim@185: double w = Math.atan(Math.sqrt((S/C)));
sascha@778:
tim@185: double D = 2.0 * w * earthRadius;
sascha@778:
tim@185: double R = Math.sqrt((S*C)) / w;
sascha@778:
tim@185: double H1 = (3.0 * R - 1.0 ) / (2.0 * C);
tim@185: double H2 = (3.0 * R + 1.0 ) / (2.0 * S);
sascha@778:
sascha@778: resultValue = D * (1 + (flattening * H1 * (Math.sin(F) * Math.sin(F)) *
sascha@778: (Math.cos(G) * Math.cos(G))) -
sascha@778: (flattening * H2 * (Math.cos(F) * Math.cos(F)) *
tim@185: (Math.sin(G) * Math.sin(G))));
sascha@778:
tim@185: return resultValue;
tim@185: }
tim@185:
ingo@806: /**
ingo@806: * Calculates the length of a path specified by coordinates in path.
ingo@806: *
ingo@806: * @param path A list of coordinates.
ingo@806: * @return the length of the given path.
ingo@806: */
sascha@362: public static final double calculateDistance(List path) {
sascha@362: int N = path.size();
sascha@362: if (N < 2) {
sascha@362: return 0d;
sascha@362: }
sascha@362: double sum = 0d;
sascha@362: for (int i = 1; i < N; ++i) {
sascha@362: sum += calculateDistance(path.get(i-1), path.get(i));
sascha@362: }
sascha@362: return sum;
sascha@362: }
sascha@362:
tim@185: }
sascha@836: // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :