问题
I'm currently using the function below and it doesn't work properly. According to Google Maps, the distance between these coordinates (from 59.3293371,13.4877472 to 59.3225525,13.4619422) are 2.2 kilometres while the function returns 1.6 kilometres. How can I make this function return the correct distance?
function getDistanceFromLatLonInKm(lat1, lon1, lat2, lon2) {
var R = 6371; // Radius of the earth in km
var dLat = deg2rad(lat2-lat1); // deg2rad below
var dLon = deg2rad(lon2-lon1);
var a =
Math.sin(dLat/2) * Math.sin(dLat/2) +
Math.cos(deg2rad(lat1)) * Math.cos(deg2rad(lat2)) *
Math.sin(dLon/2) * Math.sin(dLon/2)
;
var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
var d = R * c; // Distance in km
return d;
}
function deg2rad(deg) {
return deg * (Math.PI/180)
}
jsFiddle: http://jsfiddle.net/edgren/gAHJB/
回答1:
What you're using is called the haversine formula, which calculates the distance between two points on a sphere as the crow flies. The Google Maps link you provided shows the distance as 2.2 km because it's not a straight line.
Wolphram Alpha is a great resource for doing geographic calculations, and also shows a distance of 1.652 km between these two points.
If you're looking for straight-line distance (as the crow files), your function is working correctly. If what you want is driving distance (or biking distance or public transportation distance or walking distance), you'll have to use a mapping API (Google or Bing being the most popular) to get the appropriate route, which will include the distance.
Incidentally, the Google Maps API provides a packaged method for spherical distance, in its google.maps.geometry.spherical namespace (look for computeDistanceBetween). It's probably better than rolling your own (for starters, it uses a more precise value for the Earth's radius).
For the picky among us, when I say "straight-line distance", I'm referring to a "straight line on a sphere", which is actually a curved line (i.e. the great-circle distance), of course.
回答2:
I have written a similar equation before - tested it and also got 1.6 km.
Your google maps was showing the DRIVING distance.
Your function is calculating as the crow flies (straight line distance).
alert(calcCrow(59.3293371,13.4877472,59.3225525,13.4619422).toFixed(1));
//This function takes in latitude and longitude of two location and returns the distance between them as the crow flies (in km)
function calcCrow(lat1, lon1, lat2, lon2)
{
var R = 6371; // km
var dLat = toRad(lat2-lat1);
var dLon = toRad(lon2-lon1);
var lat1 = toRad(lat1);
var lat2 = toRad(lat2);
var a = Math.sin(dLat/2) * Math.sin(dLat/2) +
Math.sin(dLon/2) * Math.sin(dLon/2) * Math.cos(lat1) * Math.cos(lat2);
var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
var d = R * c;
return d;
}
// Converts numeric degrees to radians
function toRad(Value)
{
return Value * Math.PI / 180;
}
回答3:
Derek's solution worked fine for me, and I've just simply converted it to PHP, hope it helps somebody out there !
function calcCrow($lat1, $lon1, $lat2, $lon2){
$R = 6371; // km
$dLat = toRad($lat2-$lat1);
$dLon = toRad($lon2-$lon1);
$lat1 = toRad($lat1);
$lat2 = toRad($lat2);
$a = sin($dLat/2) * sin($dLat/2) +sin($dLon/2) * sin($dLon/2) * cos($lat1) * cos($lat2);
$c = 2 * atan2(sqrt($a), sqrt(1-$a));
$d = $R * $c;
return $d;
}
// Converts numeric degrees to radians
function toRad($Value)
{
return $Value * pi() / 180;
}
回答4:
Try this. It is in VB.net and you need to convert it to Javascript. This function accepts parameters in decimal minutes.
Private Function calculateDistance(ByVal long1 As String, ByVal lat1 As String, ByVal long2 As String, ByVal lat2 As String) As Double
long1 = Double.Parse(long1)
lat1 = Double.Parse(lat1)
long2 = Double.Parse(long2)
lat2 = Double.Parse(lat2)
'conversion to radian
lat1 = (lat1 * 2.0 * Math.PI) / 60.0 / 360.0
long1 = (long1 * 2.0 * Math.PI) / 60.0 / 360.0
lat2 = (lat2 * 2.0 * Math.PI) / 60.0 / 360.0
long2 = (long2 * 2.0 * Math.PI) / 60.0 / 360.0
' use to different earth axis length
Dim a As Double = 6378137.0 ' Earth Major Axis (WGS84)
Dim b As Double = 6356752.3142 ' Minor Axis
Dim f As Double = (a - b) / a ' "Flattening"
Dim e As Double = 2.0 * f - f * f ' "Eccentricity"
Dim beta As Double = (a / Math.Sqrt(1.0 - e * Math.Sin(lat1) * Math.Sin(lat1)))
Dim cos As Double = Math.Cos(lat1)
Dim x As Double = beta * cos * Math.Cos(long1)
Dim y As Double = beta * cos * Math.Sin(long1)
Dim z As Double = beta * (1 - e) * Math.Sin(lat1)
beta = (a / Math.Sqrt(1.0 - e * Math.Sin(lat2) * Math.Sin(lat2)))
cos = Math.Cos(lat2)
x -= (beta * cos * Math.Cos(long2))
y -= (beta * cos * Math.Sin(long2))
z -= (beta * (1 - e) * Math.Sin(lat2))
Return Math.Sqrt((x * x) + (y * y) + (z * z))
End Function
Edit The converted function in javascript
function calculateDistance(lat1, long1, lat2, long2)
{
//radians
lat1 = (lat1 * 2.0 * Math.PI) / 60.0 / 360.0;
long1 = (long1 * 2.0 * Math.PI) / 60.0 / 360.0;
lat2 = (lat2 * 2.0 * Math.PI) / 60.0 / 360.0;
long2 = (long2 * 2.0 * Math.PI) / 60.0 / 360.0;
// use to different earth axis length
var a = 6378137.0; // Earth Major Axis (WGS84)
var b = 6356752.3142; // Minor Axis
var f = (a-b) / a; // "Flattening"
var e = 2.0*f - f*f; // "Eccentricity"
var beta = (a / Math.sqrt( 1.0 - e * Math.sin( lat1 ) * Math.sin( lat1 )));
var cos = Math.cos( lat1 );
var x = beta * cos * Math.cos( long1 );
var y = beta * cos * Math.sin( long1 );
var z = beta * ( 1 - e ) * Math.sin( lat1 );
beta = ( a / Math.sqrt( 1.0 - e * Math.sin( lat2 ) * Math.sin( lat2 )));
cos = Math.cos( lat2 );
x -= (beta * cos * Math.cos( long2 ));
y -= (beta * cos * Math.sin( long2 ));
z -= (beta * (1 - e) * Math.sin( lat2 ));
return (Math.sqrt( (x*x) + (y*y) + (z*z) )/1000);
}
回答5:
Calculate the Distance between Two Points in javascript
function distance(lat1, lon1, lat2, lon2, unit) {
var radlat1 = Math.PI * lat1/180
var radlat2 = Math.PI * lat2/180
var theta = lon1-lon2
var radtheta = Math.PI * theta/180
var dist = Math.sin(radlat1) * Math.sin(radlat2) + Math.cos(radlat1) * Math.cos(radlat2) * Math.cos(radtheta);
dist = Math.acos(dist)
dist = dist * 180/Math.PI
dist = dist * 60 * 1.1515
if (unit=="K") { dist = dist * 1.609344 }
if (unit=="N") { dist = dist * 0.8684 }
return dist
}
For more details refer this: Reference Link
来源：https://stackoverflow.com/questions/18883601/function-to-calculate-distance-between-two-coordinates