Measuring the distance between two coordinates in

Question

Hi I have the need to calculate the distance between two points having the lat and long.

I would like to avoid any call to external API.

I tried to implement the Haversine Formula in PHP:

Here is the code:

class CoordDistance
 {
    public $lat_a = 0;
    public $lon_a = 0;
    public $lat_b = 0;
    public $lon_b = 0;

    public $measure_unit = 'kilometers';

    public $measure_state = false;

    public $measure = 0;

    public $error = '';



    public function DistAB()

      {
          $delta_lat = $this->lat_b - $this->lat_a ;
          $delta_lon = $this->lon_b - $this->lon_a ;

          $earth_radius = 6372.795477598;

          $alpha    = $delta_lat/2;
          $beta     = $delta_lon/2;
          $a        = sin(deg2rad($alpha)) * sin(deg2rad($alpha)) + cos(deg2rad($this->lat_a)) * cos(deg2rad($this->lat_b)) * sin(deg2rad($beta)) * sin(deg2rad($beta)) ;
          $c        = asin(min(1, sqrt($a)));
          $distance = 2*$earth_radius * $c;
          $distance = round($distance, 4);

          $this->measure = $distance;

      }
    }

Testing it with some given points which have public distances I don't get a reliable result.

I don't understand if there is an error in the original formula or in my implementation

Answer 1

Hello here Code For Get Distance and Time Using Two Different Lat and Long

$url ="https://maps.googleapis.com/maps/api/distancematrix/json?units=imperial&origins=16.538048,80.613266&destinations=23.0225,72.5714";



    $ch = curl_init();
    // Disable SSL verification

    curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
    // Will return the response, if false it print the response
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    // Set the url
    curl_setopt($ch, CURLOPT_URL,$url);
    // Execute
    $result=curl_exec($ch);
    // Closing
    curl_close($ch);

    $result_array=json_decode($result);
print_r($result_array);

You can check Example Below Link get time between two different locations using latitude and longitude in php

Answer 2

It's just addition to @martinstoeckli and @Janith Chinthana answers. For those who curious about which algorithm is fastest i wrote the performance test. Best performance result shows optimized function from codexworld.com:

/**
 * Optimized algorithm from http://www.codexworld.com
 *
 * @param float $latitudeFrom
 * @param float $longitudeFrom
 * @param float $latitudeTo
 * @param float $longitudeTo
 *
 * @return float [km]
 */
function codexworldGetDistanceOpt($latitudeFrom, $longitudeFrom, $latitudeTo, $longitudeTo)
{
    $rad = M_PI / 180;
    //Calculate distance from latitude and longitude
    $theta = $longitudeFrom - $longitudeTo;
    $dist = sin($latitudeFrom * $rad) 
        * sin($latitudeTo * $rad) +  cos($latitudeFrom * $rad)
        * cos($latitudeTo * $rad) * cos($theta * $rad);

    return acos($dist) / $rad * 60 *  1.853;
}

Here is test results:

Test name       Repeats         Result          Performance     
codexworld-opt  10000           0.084952 sec    +0.00%
codexworld      10000           0.104127 sec    -22.57%
custom          10000           0.107419 sec    -26.45%
custom2         10000           0.111576 sec    -31.34%
custom1         10000           0.136691 sec    -60.90%
vincenty        10000           0.165881 sec    -95.26%

Answer 3

Quite old question, but for those interested in a PHP code that returns the same results as Google Maps, the following does the job:

/**
 * Computes the distance between two coordinates.
 *
 * Implementation based on reverse engineering of
 * <code>google.maps.geometry.spherical.computeDistanceBetween()</code>.
 *
 * @param float $lat1 Latitude from the first point.
 * @param float $lng1 Longitude from the first point.
 * @param float $lat2 Latitude from the second point.
 * @param float $lng2 Longitude from the second point.
 * @param float $radius (optional) Radius in meters.
 *
 * @return float Distance in meters.
 */
function computeDistance($lat1, $lng1, $lat2, $lng2, $radius = 6378137)
{
    static $x = M_PI / 180;
    $lat1 *= $x; $lng1 *= $x;
    $lat2 *= $x; $lng2 *= $x;
    $distance = 2 * asin(sqrt(pow(sin(($lat1 - $lat2) / 2), 2) + cos($lat1) * cos($lat2) * pow(sin(($lng1 - $lng2) / 2), 2)));

    return $distance * $radius;
}

I've tested with various coordinates and it works perfectly.

I think it should be faster then some alternatives too. But didn't tested that.

Hint: Google Maps uses 6378137 as Earth radius. So using it with other algorithms might work as well.

Answer 4

I found this code which is giving me reliable results.

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;
  }
}

results :

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>";

Answer 5

The multiplier is changed at every coordinate because of the great circle distance theory as written here :

http://en.wikipedia.org/wiki/Great-circle_distance

and you can calculate the nearest value using this formula described here:

http://en.wikipedia.org/wiki/Great-circle_distance#Worked_example

the key is converting each degree - minute - second value to all degree value:

N 36°7.2', W 86°40.2'  N = (+) , W = (-), S = (-), E = (+) 
referencing the Greenwich meridian and Equator parallel

(phi)     36.12° = 36° + 7.2'/60' 

(lambda)  -86.67° = 86° + 40.2'/60'

Answer 6

Try this gives awesome results

function getDistance($point1_lat, $point1_long, $point2_lat, $point2_long, $unit = 'km', $decimals = 2) {
        // Calculate the distance in degrees
        $degrees = rad2deg(acos((sin(deg2rad($point1_lat))*sin(deg2rad($point2_lat))) + (cos(deg2rad($point1_lat))*cos(deg2rad($point2_lat))*cos(deg2rad($point1_long-$point2_long)))));

        // Convert the distance in degrees to the chosen unit (kilometres, miles or nautical miles)
        switch($unit) {
            case 'km':
                $distance = $degrees * 111.13384; // 1 degree = 111.13384 km, based on the average diameter of the Earth (12,735 km)
                break;
            case 'mi':
                $distance = $degrees * 69.05482; // 1 degree = 69.05482 miles, based on the average diameter of the Earth (7,913.1 miles)
                break;
            case 'nmi':
                $distance =  $degrees * 59.97662; // 1 degree = 59.97662 nautic miles, based on the average diameter of the Earth (6,876.3 nautical miles)
        }
        return round($distance, $decimals);
    }