Compute Latitude and Longitude to Kilometer

Question

I'm trying to calculate my Kilometer distance from my Destination1 to Destination2 using latitude and longitude

Destination1(Cebu City PH) has Latitude: 1017.8590 and Longitude: 12353.4304

Destination2(Talisay PH) has Latitude: 1015.6445 and Longitude: 12350.0404

My output is: 299.28607720457882 KM

CODE:

double lat1 = Convert.ToDouble(txtLat1.Text.ToString());
double lat2 = Convert.ToDouble(txtLat2.Text.ToString());
double lon1 = Convert.ToDouble(txtLong1.Text.ToString());
double lon2 = Convert.ToDouble(txtLong2.Text.ToString());

        var R = 6378.137; // Radius of earth in KM
        var dLat = (lat2 - lat1) * Math.PI / 180;
        var dLon = (lon2 - lon1) * Math.PI / 180;
        var a =
            Math.Sin(dLat / 2) * Math.Sin(dLat / 2) +
            Math.Cos(lat1 * Math.PI / 180) * Math.Cos(lat2 * Math.PI / 180) *
            Math.Sin(dLon / 2) * Math.Sin(dLon / 2);
        var c = 2 * Math.Atan2(Math.Sqrt(a), Math.Sqrt(1 - a));
        string x = (R * c).ToString();
        var d = (R * c);

I try using http://www.entfernungsrechner.net/en/distance/city/1717512/city/1683881 this website to calculate the Kilometer of that Destination and the output is 12.2 km

299.28607724057882km! Calculating distance to the nanometer is obviously going to be useful — , Mar 12 '15 at 04:17
how can it be useful HoboSapiens? can you show me some links or code? — See Yah Later, Mar 12 '15 at 04:26

Ray Suelzer · Accepted Answer · 2015-03-12T05:08:14.383

1

Well, for starters it says 12.2KM as you would drive. Which is not going to be the same output as your Haversine formula you have above.

You should try putting the decimals in the right spots. I get a more reasonable result of 4.45 Kilometers.

https://dotnetfiddle.net/cs5Ppq

public class Program
{
    public static void Main()
    {
        double lat1 = 10.178590;
        double lat2 = 10.156445;
        double lon1 = 123.500404;
        double lon2 = 123.534304;

        var R = 6378.137; // Radius of earth in KM
        var dLat = (lat2 - lat1) * Math.PI / 180;
        var dLon = (lon2 - lon1) * Math.PI / 180;
        var a =
            Math.Sin(dLat / 2) * Math.Sin(dLat / 2) +
            Math.Cos(lat1 * Math.PI / 180) * Math.Cos(lat2 * Math.PI / 180) *
            Math.Sin(dLon / 2) * Math.Sin(dLon / 2);
        var c = 2 * Math.Atan2(Math.Sqrt(a), Math.Sqrt(1 - a));
        string x = (R * c).ToString();
        var d = (R * c);
        Console.WriteLine(d);
    }
}

Note: you can check your results against this http://andrew.hedges.name/experiments/haversine/ tool

Edit: If you want the most possibly accurate number, as the Haversine formula can underestimate and overestimate distances at the extremes on the earth, you want to use the Vincety solution. This is not for the weak of heart: http://www.movable-type.co.uk/scripts/latlong-vincenty.html

edited Mar 12 '15 at 05:08

answered Mar 12 '15 at 04:42

Ray Suelzer

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but base in distances its 9KM and base in results its 4.45KM. I guess its still lacking. but if it gets 7KM and above that would be the great answer – See Yah Later Mar 12 '15 at 05:01
The approximate airline distance they calculate is 9KM, since I can't see how they calculate this, I'm not sure I trust it. – Ray Suelzer Mar 12 '15 at 05:05
Using the Vincenty forumla you will get 4449.704 meters, which is accurate to the millimeter. The website you are referencing is wrong, or is calculating distance between airports. – Ray Suelzer Mar 12 '15 at 05:14
Also if you look at their source code they are using different coordinates than you provided. `(10.3167200, 123.8907100); (10.2447200, 123.8494400);` which yeilds 9.20186196876873 KM – Ray Suelzer Mar 12 '15 at 05:20
Thanks for showing me that code. I really can't get in there source code. Thanks – See Yah Later Mar 12 '15 at 05:28
Right click, "view source". :) – Ray Suelzer Mar 12 '15 at 05:29
On the **Calculate** button? – See Yah Later Mar 12 '15 at 05:31

Compute Latitude and Longitude to Kilometer

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