Convert Latitude and Longitude into kms

问题

I am building application where i am getting the user's latitude and longitude using the below code

<!DOCTYPE html> <html> <body>

<p>Click the button to get your coordinates.</p>

<button onclick="getLocation()">Try It</button>

<p id="demo"></p>

<script> var x = document.getElementById("demo");

function getLocation() {
    if (navigator.geolocation) {
        navigator.geolocation.getCurrentPosition(showPosition);
    } else { 
        x.innerHTML = "Geolocation is not supported by this browser.";
    } }

function showPosition(position) {
    x.innerHTML = "Latitude: " + position.coords.latitude + 
    "<br>Longitude: " + position.coords.longitude;   } </script>

</body> </html>

Now i want to convert it to kilometre so that i can compare with other latitude and longitude and calculate the difference between them in kilometre.

回答1:

This Script is usefull for you, but its in php

function distance($lat1, $lon1, $lat2, $lon2, $unit) {

      $theta = $lon1 - $lon2;
      $dist = sin(deg2rad($lat1)) * sin(deg2rad($lat2)) +  cos(deg2rad($lat1)) * cos(deg2rad($lat2)) * cos(deg2rad($theta));
       $dist = acos($dist);
       $dist = rad2deg($dist);
      $miles = $dist * 60 * 1.1515;
      $unit = strtoupper($unit);

 if ($unit == "K") {
   return ($miles * 1.609344);
     } else if ($unit == "N") {
     return ($miles * 0.8684);
      } else {
      return $miles;
     }
  }

Function to use

  echo distance(32.9697, -96.80322, 29.46786, -98.53506, "M") . " Miles<br>";
  echo distance(32.9697, -96.80322, 29.46786, -98.53506, "K") . " Kilometers<br>";
  echo distance(32.9697, -96.80322, 29.46786, -98.53506, "N") . " Nautical Miles<br>";

回答2:

Considering that a latitude and longitude is a specific point, you cannot convert this directly to kilometers, which is a distance i.e. the length separating two points.

But you can get the distance between two coordinates (lat+long) with a math formula. I am not really good at math, but you could find such formula with a simple search on Google: here is the first result

You may also find something useful on this topic: How to convert latitude or longitude to meters?

回答3:

What you're looking for is called the Haversine formula; there's a PHP implementation here.

来源：https://stackoverflow.com/questions/28536733/convert-latitude-and-longitude-into-kms

标签

php

laravel-4

latitude-longitude