Distance between two locations isn't right
문제
I have used the algorithm on http://www.movable-type.co.uk/scripts/latlong.html to find the distance between two points.
My two points are
long1 = 51.507467;
lat1 = -0.08776;
long2 = 51.508736;
lat2 = -0.08612;
According to Movable Type Script the answer is 0.1812km
My application gives the result (d
) as 0.230km
Check Haversine formula: http://www.movable-type.co.uk/scripts/latlong.html
double R = 6371; // earth’s radius (mean radius = 6,371km)
double dLat = Math.toRadians(lat2-lat1);
double dLon = Math.toRadians(long2-long1);
a = Math.sin(dLat/2) * Math.sin(dLat/2) +
Math.cos(Math.toRadians(lat1)) * Math.cos(Math.toRadians(lat2)) *
Math.sin(dLon/2) * Math.sin(dLon/2);
double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
double d = R * c;
해결책
Why to reinvent your own distance calculator, there is one built into the Location class.
Check out
distanceBetween(double startLatitude, double startLongitude, double endLatitude, double endLongitude, float[] results)
Computes the approximate distance in meters between two locations, and optionally the initial and final bearings of the shortest path between them.
다른 팁
Your implementation is correct. The distance given those longitudes and latitudes should produce a distance of 0.230 km
. The normal input for coordinates, however, is (latitude, longitude). Putting them in backwards (longitude, latitude) produces the incorrect distance of 0.1812 km
.
public double CalculationByDistance(GeoPoint StartP, GeoPoint EndP) {
double lat1 = StartP.getLatitudeE6()/1E6;
double lat2 = EndP.getLatitudeE6()/1E6;
double lon1 = StartP.getLongitudeE6()/1E6;
double lon2 = EndP.getLongitudeE6()/1E6;
double dLat = Math.toRadians(lat2-lat1);
double dLon = Math.toRadians(lon2-lon1);
double a = Math.sin(dLat/2) * Math.sin(dLat/2) +
Math.cos(Math.toRadians(lat1)) * Math.cos(Math.toRadians(lat2)) *
Math.sin(dLon/2) * Math.sin(dLon/2);
double c = 2 * Math.asin(Math.sqrt(a));
return Radius * c;
}
Ally your concept was right.May be a little bit chang in this line double c = 2 * Math.asin(Math.sqrt(a));