package xxx.driver.business.utils; /** * <p>Represents a point on the surface of a sphere. (The Earth is almost * spherical.)</p> * * <p>To create an instance, call one of the static methods fromDegrees() or * fromRadians().</p> * * <p>This code was originally published at * <a href="http://JanMatuschek.de/LatitudeLongitudeBoundingCoordinates#Java"> * http://JanMatuschek.de/LatitudeLongitudeBoundingCoordinates#Java</a>.</p> * * @author Jan Philip Matuschek * @version 22 September 2010 */ public class GeoLocation { private double radLat; // latitude in radians private double radLon; // longitude in radians private double degLat; // latitude in degrees private double degLon; // longitude in degrees private static final double EARTHS_RADIUS_KM = 6371.01; private static final double EARTHS_RADIUS_M = 3958.762079; public static final int UNIT_KM = 0; public static final int UNIT_M = 1; private static final double MIN_LAT = Math.toRadians(-90d); // -PI/2 private static final double MAX_LAT = Math.toRadians(90d); // PI/2 private static final double MIN_LON = Math.toRadians(-180d); // -PI private static final double MAX_LON = Math.toRadians(180d); // PI private GeoLocation () { } /** * @param latitude the latitude, in degrees. * @param longitude the longitude, in degrees. */ public static GeoLocation fromDegrees(double latitude, double longitude) { GeoLocation result = new GeoLocation(); result.radLat = Math.toRadians(latitude); result.radLon = Math.toRadians(longitude); result.degLat = latitude; result.degLon = longitude; result.checkBounds(); return result; } /** * * @param unit 0 km || kilometers; 1 m || miles * @return */ protected double getEarthsRadius(int unit) { return unit == UNIT_KM?EARTHS_RADIUS_KM:EARTHS_RADIUS_M; } /** * @param latitude the latitude, in radians. * @param longitude the longitude, in radians. */ public static GeoLocation fromRadians(double latitude, double longitude) { GeoLocation result = new GeoLocation(); result.radLat = latitude; result.radLon = longitude; result.degLat = Math.toDegrees(latitude); result.degLon = Math.toDegrees(longitude); result.checkBounds(); return result; } private void checkBounds() { if (radLat < MIN_LAT || radLat > MAX_LAT || radLon < MIN_LON || radLon > MAX_LON) throw new IllegalArgumentException(); } /** * @return the latitude, in degrees. */ public double getLatitudeInDegrees() { return degLat; } /** * @return the longitude, in degrees. */ public double getLongitudeInDegrees() { return degLon; } /** * @return the latitude, in radians. */ public double getLatitudeInRadians() { return radLat; } /** * @return the longitude, in radians. */ public double getLongitudeInRadians() { return radLon; } @Override public String toString() { return "(" + degLat + "u00B0, " + degLon + "u00B0) = (" + radLat + " rad, " + radLon + " rad)"; } /** * Computes the great circle distance between this GeoLocation instance * and the location argument. * @param radius the radius of the sphere, e.g. the average radius for a * spherical approximation of the figure of the Earth is approximately * 6371.01 kilometers. * @return the distance, measured in the same unit as the radius * argument. */ public double distanceTo(GeoLocation location, double radius) { return Math.acos(Math.sin(radLat) * Math.sin(location.radLat) + Math.cos(radLat) * Math.cos(location.radLat) * Math.cos(radLon - location.radLon)) * radius; } /** * * @param location * @param unit * @return */ public double distanceToByUnit(GeoLocation location, int unit) { return distanceTo(location, getEarthsRadius(unit)); } /** * <p>Computes the bounding coordinates of all points on the surface * of a sphere that have a great circle distance to the point represented * by this GeoLocation instance that is less or equal to the distance * argument.</p> * <p>For more information about the formulae used in this method visit * <a href="http://JanMatuschek.de/LatitudeLongitudeBoundingCoordinates"> * http://JanMatuschek.de/LatitudeLongitudeBoundingCoordinates</a>.</p> * @param distance the distance from the point represented by this * GeoLocation instance. Must me measured in the same unit as the radius * argument. * @param radius the radius of the sphere, e.g. the average radius for a * spherical approximation of the figure of the Earth is approximately * 6371.01 kilometers. * @return an array of two GeoLocation objects such that:<ul> * <li>The latitude of any point within the specified distance is greater * or equal to the latitude of the first array element and smaller or * equal to the latitude of the second array element.</li> * <li>If the longitude of the first array element is smaller or equal to * the longitude of the second element, then * the longitude of any point within the specified distance is greater * or equal to the longitude of the first array element and smaller or * equal to the longitude of the second array element.</li> * <li>If the longitude of the first array element is greater than the * longitude of the second element (this is the case if the 180th * meridian is within the distance), then * the longitude of any point within the specified distance is greater * or equal to the longitude of the first array element * <strong>or</strong> smaller or equal to the longitude of the second * array element.</li> * </ul> */ public GeoLocation[] boundingCoordinates(double distance, double radius) { if (radius < 0d || distance < 0d) throw new IllegalArgumentException(); // angular distance in radians on a great circle double radDist = distance / radius; double minLat = radLat - radDist; double maxLat = radLat + radDist; double minLon, maxLon; if (minLat > MIN_LAT && maxLat < MAX_LAT) { double deltaLon = Math.asin(Math.sin(radDist) / Math.cos(radLat)); minLon = radLon - deltaLon; if (minLon < MIN_LON) minLon += 2d * Math.PI; maxLon = radLon + deltaLon; if (maxLon > MAX_LON) maxLon -= 2d * Math.PI; } else { // a pole is within the distance minLat = Math.max(minLat, MIN_LAT); maxLat = Math.min(maxLat, MAX_LAT); minLon = MIN_LON; maxLon = MAX_LON; } return new GeoLocation[]{fromRadians(minLat, minLon), fromRadians(maxLat, maxLon)}; } }