working out distances between two points using google maps api?

Question

Is it possible to send two lat long points to google to calculate the distance between the two?

Answer 1

Yes google can do this

google api docs

here's a piece of java script that get's the distance in km's for two points

function initialize() {
      if (GBrowserIsCompatible()) {
          map = new GMap2(document.getElementById("map_canvas"));
          map.setCenter(new GLatLng(52.6345701, -1.1294433), 13);
          map.addControl(new GLargeMapControl());          
          map.addControl(new GMapTypeControl());
          geocoder = new GClientGeocoder();

          // NR14 7PZ
          var loc1 = new GLatLng(52.5773139, 1.3712427);
          // NR32 1TB
          var loc2 = new GLatLng(52.4788314, 1.7577444);          
          alert(loc2.distanceFrom(loc1) / 1000);
      }
    }

Answer 2

No, but you can use Vincenty's formula, which models the shape of the Earth. It's available in Javascript here.

A quite easy to parse web page is (e.g.): http://boulter.com/gps/distance/?from=51.5329855+-0.1303506&to=40.757584+-73.985642&units=m

For people who only want a quick measure of distance, check out this gadget. However, it only uses the great circle calculation.

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As Rob notes, Google have added it, but they still only use the great circle formula, which can be inaccurate by 1/300.

Answer 3

What you're after is the Haversine formula. You don't need Google Maps to do this, you can work it out separately. There's a script to do this (in JavaScript) here.

Answer 4

Its been many years since I did this but you could use the Great Circle Distance

Answer 5

If you just want to get the distance as a number, try something like this.

function InitDistances() {
    var startLocation = new GLatLng(startLat, startLon);
    var endLocation = new GLatLng(endLat, endLon);
    var dist = startLocation .distanceFrom(endLocation);

    // Convert distance to miles with two decimal points precision
    return (dist / 1609.344).toFixed(2);
}

Answer 6

And the distance cal in c#:

// this returns the distance in miles. for km multiply result: * 1.609344
public static double CalculateDistance(double lat1, double lon1, double lat2, double lon2)
{
    double t = lon1 - lon2;
    double distance = Math.Sin(Degree2Radius(lat1)) * Math.Sin(Degree2Radius(lat2)) + Math.Cos(Degree2Radius(lat1)) * Math.Cos(Degree2Radius(lat2)) * Math.Cos(Degree2Radius(t));
    distance = Math.Acos(distance);
    distance = Radius2Degree(distance);
    distance = distance * 60 * 1.1515;

    return distance;
}

private static double Degree2Radius(double deg)
{
    return (deg * Math.PI / 180.0);
}

private static double Radius2Degree(double rad)
{
    return rad / Math.PI * 180.0;
}