CODEWITHSUNDEEP
phpgoogle-maps
Dario
Dario

Reputation: 437

detecting point within polygon (latitude and longitude) in PHP

I have array (polygon)

[[-24.837452, -65.452484],[-24.837433,  -65.450645],[-24.828865000000004,  -65.449997],[-24.828709,  -65.451607],[-24.837452,  -65.452484]]

and point -24.8330000, -65.452484

how to detect if the point is inside the polygon?

If I use the array of examples works. if you use real coordinates it does not work...

<?php

        class pointLocation {
            var $pointOnVertex = true; // Checar si el punto se encuentra exactamente en uno de los vértices?

            function pointLocation() {
            }

                function pointInPolygon($point, $polygon, $pointOnVertex = true) {
                $this->pointOnVertex = $pointOnVertex;

                // Transformar la cadena de coordenadas en matrices con valores "x" e "y"
                $point = $this->pointStringToCoordinates($point);
                $vertices = array(); 
                foreach ($polygon as $vertex) {
                    $vertices[] = $this->pointStringToCoordinates($vertex); 
                }

                // Checar si el punto se encuentra exactamente en un vértice
                if ($this->pointOnVertex == true and $this->pointOnVertex($point, $vertices) == true) {
                    return "vertex";
                }

                // Checar si el punto está adentro del poligono o en el borde
                $intersections = 0; 
                $vertices_count = count($vertices);

                for ($i=1; $i < $vertices_count; $i++) {
                    $vertex1 = $vertices[$i-1]; 
                    $vertex2 = $vertices[$i];
                    if ($vertex1['y'] == $vertex2['y'] and $vertex1['y'] == $point['y'] and $point['x'] > min($vertex1['x'], $vertex2['x']) and $point['x'] < max($vertex1['x'], $vertex2['x'])) { // Checar si el punto está en un segmento horizontal
                        return "boundary";
                    }
                    if ($point['y'] > min($vertex1['y'], $vertex2['y']) and $point['y'] <= max($vertex1['y'], $vertex2['y']) and $point['x'] <= max($vertex1['x'], $vertex2['x']) and $vertex1['y'] != $vertex2['y']) { 
                        $xinters = ($point['y'] - $vertex1['y']) * ($vertex2['x'] - $vertex1['x']) / ($vertex2['y'] - $vertex1['y']) + $vertex1['x']; 
                        if ($xinters == $point['x']) { // Checar si el punto está en un segmento (otro que horizontal)
                            return "boundary";
                        }
                        if ($vertex1['x'] == $vertex2['x'] || $point['x'] <= $xinters) {
                            $intersections++; 
                        }
                    } 
                } 
                // Si el número de intersecciones es impar, el punto está dentro del poligono. 
                if ($intersections % 2 != 0) {
                    return "inside";
                } else {
                    return "outside";
                }
            }

            function pointOnVertex($point, $vertices) {
                foreach($vertices as $vertex) {
                    if ($point == $vertex) {
                        return true;
                    }
                }

            }

            function pointStringToCoordinates($pointString) {
                $coordinates = explode(" ", $pointString);
                return array("x" => $coordinates[0], "y" => $coordinates[1]);
            }

        }


    //original examples is OK
    //$points = array("50 70","70 40","-20 30","100 10","-10 -10","40 -20","110 -20");
    //$polygon = array("-50 30","50 70","100 50","80 10","110 -10","110 -30","-20 -50","-30 -40","10 -10","-10 10","-30 -20","-50 30");


        $json="[[-24.837452, -65.452484],[-24.837433,  -65.450645],[-24.828865000000004,  -65.449997],[-24.828709,  -65.451607],[-24.837452,  -65.452484]]";
        $resultado = str_replace(",", "", $json);
        $resultado = str_replace("[[", "", $resultado);
        $resultado = str_replace("]]", "", $resultado);

        $polygon=explode("][", $resultado);

        $points=array("-24.8330000 -65.452484");

         //print_r ($resultado);
        $pointLocation = new pointLocation();

        // Las últimas coordenadas tienen que ser las mismas que las primeras, para "cerrar el círculo"
        foreach($points as $key => $point) {
            echo "point " . ($key+1) . " ($point): " . $pointLocation->pointInPolygon($point, $polygon) . "<br>";
        }
        ?>

These data are real and the point is within the polygon

[[-24.837452, -65.452484],[-24.837433, -65.450645],[-24.828865000000004, -65.449997],[-24.828709, -65.451607],[-24.837452, -65.452484]]

and point -24.8330000, -65.452484

Upvotes: 4

Views: 6963

Answers (6)

tony gil
tony gil

Reputation: 9554

Gave Lavanya E.'s answer a couple of tweaks, because it wasn't running for me.

Since my application requires checking multiple points against multiple polygons (fence areas), I also adapted JSON to work with nested arrays.

<?php

ini_set('display_errors', '1');
ini_set('display_startup_errors', '1');
error_reporting(E_ALL);

echo "start decoding JSON</br>";

$pointArray=json_decode('[{"lat": 15.381533561369851, "lng": 73.90972848645542}, {"lat": 12.381533561369851, "lng": 73.90972848645542}]', true);

$fenceAreaArray=json_decode('[{"0":[{"lat":15.20184549675828,"lng":73.97872613764991},{"lat":15.10939000042012,"lng":73.93821405268898},{"lat":15.035131321967592,"lng":74.00619195796241},{"lat":14.991027988389707,"lng":74.05288385249366},{"lat":14.97268353612274,"lng":74.10815881587257},{"lat":15.08885107597101,"lng":74.17785333491554},{"lat":15.179658827735558,"lng":74.16652368403663},{"lat":15.245254746972826,"lng":74.18746637202491},{"lat":15.31261799705796,"lng":74.1534774193882},{"lat":15.35260926883264,"lng":74.06195113314038},{"lat":15.396694714469158,"lng":73.96676107157123},{"lat":15.480490697370463,"lng":73.91443209172701},{"lat":15.485848509162427,"lng":73.84096243101556},{"lat":15.58045246934704,"lng":73.83169271666009},{"lat":15.596325797024097,"lng":73.75410177427727},{"lat":15.406706231349043,"lng":73.79266521010072}], "1":[{"lat":12.20184549675828,"lng":73.97872613764991},{"lat":12.10939000042012,"lng":73.93821405268898},{"lat":12.035131321967592,"lng":74.00619195796241},{"lat":11.991027988389707,"lng":74.05288385249366},{"lat":11.97268353612274,"lng":74.10815881587257},{"lat":12.08885107597101,"lng":74.17785333491554},{"lat":12.179658827735558,"lng":74.16652368403663},{"lat":12.245254746972826,"lng":74.18746637202491},{"lat":12.31261799705796,"lng":74.1534774193882},{"lat":12.35260926883264,"lng":74.06195113314038},{"lat":12.396694714469158,"lng":73.96676107157123},{"lat":12.480490697370463,"lng":73.91443209172701},{"lat":12.485848509162427,"lng":73.84096243101556},{"lat":12.58045246934704,"lng":73.83169271666009},{"lat":12.596325797024097,"lng":73.75410177427727},{"lat":12.406706231349043,"lng":73.79266521010072}]}]', true); 

echo "pointArray has [".count($pointArray)."] elements</br>";
echo "fenceAreaArray[0] has [".count($fenceAreaArray[0])."] elements</br>";

// loop thru pointArray 
foreach ($pointArray as $k => $pointOut) {
  // get the first (and only element) from fenceAreaArray and loop
  foreach ($fenceAreaArray[0] as $l => $fenceAreaOut) {
    $resultInside = inside($pointOut,$fenceAreaOut);
    echo "</br>This is the result for point[$k] and fenceArea[$l]: [$resultInside]";
  }     
}

function inside($point, $fenceArea) {

    //echo "hello from the INSIDE </br>";
        
    $x = $point['lat']; 
    $y = $point['lng'];

    $inside = false;
    for ($i = 0, $j = count($fenceArea) - 1; $i <  count($fenceArea); $j = $i++) {
        $xi = $fenceArea[$i]['lat']; $yi = $fenceArea[$i]['lng'];
        $xj = $fenceArea[$j]['lat']; $yj = $fenceArea[$j]['lng'];

        $intersect = (($yi > $y) != ($yj > $y))
        && ($x < ($xj - $xi) * ($y - $yi) / ($yj - $yi) + $xi);
        if ($intersect) $inside = !$inside;
    }

    return $inside;
}

?>

Upvotes: 0

Lavanya E
Lavanya E

Reputation: 216

function inside($point, $fenceArea) {
$x = $point['lat']; $y = $point['lng'];

$inside = false;
for ($i = 0, $j = count($fenceArea) - 1; $i <  count($fenceArea); $j = $i++) {
    $xi = $fenceArea[$i]['lat']; $yi = $fenceArea[$i]['lng'];
    $xj = $fenceArea[$j]['lat']; $yj = $fenceArea[$j]['lng'];

    $intersect = (($yi > $y) != ($yj > $y))
        && ($x < ($xj - $xi) * ($y - $yi) / ($yj - $yi) + $xi);
    if ($intersect) $inside = !$inside;
}

return $inside;
}
echo inside($point,$fenceArea);

$fenceArea => array of multiple lat lng $fenceArea=json_decode('[{"lat":15.20184549675828,"lng":73.97872613764991},{"lat":15.10939000042012,"lng":73.93821405268898},{"lat":15.035131321967592,"lng":74.00619195796241},{"lat":14.991027988389707,"lng":74.05288385249366},{"lat":14.97268353612274,"lng":74.10815881587257},{"lat":15.08885107597101,"lng":74.17785333491554},{"lat":15.179658827735558,"lng":74.16652368403663},{"lat":15.245254746972826,"lng":74.18746637202491},{"lat":15.31261799705796,"lng":74.1534774193882},{"lat":15.35260926883264,"lng":74.06195113314038},{"lat":15.396694714469158,"lng":73.96676107157123},{"lat":15.480490697370463,"lng":73.91443209172701},{"lat":15.485848509162427,"lng":73.84096243101556},{"lat":15.58045246934704,"lng":73.83169271666009},{"lat":15.596325797024097,"lng":73.75410177427727},{"lat":15.406706231349043,"lng":73.79266521010072}]'); $point => Searching particular lat lng $point=["lat": 15.381533561369851, "lng": 73.90972848645542];

If the point is inside fenceArea return true else it will return false.

Upvotes: 4

Wade
Wade

Reputation: 129

Here is a working implementation of your problem with the Google Maps API (since you tagged it): jsFiddle

google.maps.geometry.poly.containsLocation(testPointCoords, polygonObject) returns true if the point is in the polygon or false if the point is outside the polygon.

More information about the geometry library is here: Google Maps Geometry Library

And the containsLocation() function: contains Location()

Upvotes: 1

Dario
Dario

Reputation: 437

Had already solved more spaces at coordinates

    <?php
    /*
    Descripción: El algoritmo del punto en un polígono permite comprobar mediante
    programación si un punto está dentro de un polígono o fuera de ello.
    Autor: Michaël Niessen (2009)
    Sito web: AssemblySys.com

    Si este código le es útil, puede mostrar su
    agradecimiento a Michaël ofreciéndole un café ;)
    PayPal: [email protected]

    Mientras estos comentarios (incluyendo nombre y detalles del autor) estén
    incluidos y SIN ALTERAR, este código está distribuido bajo la GNU Licencia
    Pública General versión 3: http://www.gnu.org/licenses/gpl.html
    */

    class pointLocation {
        var $pointOnVertex = true; // Checar si el punto se encuentra exactamente en uno de los vértices?

        function pointLocation() {
        }

            function pointInPolygon($point, $polygon, $pointOnVertex = true) {
            $this->pointOnVertex = $pointOnVertex;

            // Transformar la cadena de coordenadas en matrices con valores "x" e "y"
            $point = $this->pointStringToCoordinates($point);
            $vertices = array(); 
            foreach ($polygon as $vertex) {
                $vertices[] = $this->pointStringToCoordinates($vertex); 
            }

            // Checar si el punto se encuentra exactamente en un vértice
            if ($this->pointOnVertex == true and $this->pointOnVertex($point, $vertices) == true) {
                return "vertex";
            }

            // Checar si el punto está adentro del poligono o en el borde
            $intersections = 0; 
            $vertices_count = count($vertices);

            for ($i=1; $i < $vertices_count; $i++) {
                $vertex1 = $vertices[$i-1]; 
                $vertex2 = $vertices[$i];
                if ($vertex1['y'] == $vertex2['y'] and $vertex1['y'] == $point['y'] and $point['x'] > min($vertex1['x'], $vertex2['x']) and $point['x'] < max($vertex1['x'], $vertex2['x'])) { // Checar si el punto está en un segmento horizontal
                    return "boundary";
                }
                if ($point['y'] > min($vertex1['y'], $vertex2['y']) and $point['y'] <= max($vertex1['y'], $vertex2['y']) and $point['x'] <= max($vertex1['x'], $vertex2['x']) and $vertex1['y'] != $vertex2['y']) { 
                    $xinters = ($point['y'] - $vertex1['y']) * ($vertex2['x'] - $vertex1['x']) / ($vertex2['y'] - $vertex1['y']) + $vertex1['x']; 
                    if ($xinters == $point['x']) { // Checar si el punto está en un segmento (otro que horizontal)
                        return "boundary";
                    }
                    if ($vertex1['x'] == $vertex2['x'] || $point['x'] <= $xinters) {
                        $intersections++; 
                    }
                } 
            } 
            // Si el número de intersecciones es impar, el punto está dentro del poligono. 
            if ($intersections % 2 != 0) {
                return "inside";
            } else {
                return "outside";
            }
        }

        function pointOnVertex($point, $vertices) {
            foreach($vertices as $vertex) {
                if ($point == $vertex) {
                    return true;
                }
            }

        }

        function pointStringToCoordinates($pointString) {
            $coordinates = explode(" ", $pointString);
            return array("x" => $coordinates[0], "y" => $coordinates[1]);
        }

    }

    $json="[[-24.755444000000004, -65.466476],[-24.755365, -65.466652],[-24.758835, -65.466797],[-24.760336, -65.46637],[-24.761738, -65.465683],[-24.762362, -65.46553000000002],[-24.76733, -65.466927],[-24.767447, -65.464035],[-24.766182,  -65.464035],[-24.765907000000002,  -65.463577],[-24.765070000000005,  -65.4636],[-24.76507,  -65.464249],[-24.76392,  -65.464119],[-24.763219999999997,  -65.464035],[-24.762907,  -65.464249],[-24.762402,  -65.464378],[-24.761951,  -65.464157],[-24.761738,  -65.463837],[-24.761465000000005,  -65.463455],[-24.757647,  -65.46315],[-24.755444000000004,  -65.466476]]";
//aca estaba el error (here the error)
    $resultado = str_replace(" ", "", $json);
    $resultado = str_replace(",", " ", $resultado);
    $resultado = str_replace("[[", "", $resultado);
    $resultado = str_replace("]]", "", $resultado);

    $polygon=explode("] [", $resultado);


    $points=array("-24.762426 -65.464812");

     print_r ($polygon);
    $pointLocation = new pointLocation();
    //$points = array("50 70","70 40","-20 30","100 10","-10 -10","40 -20","110 -20");
    //$polygon = array("-50 30","50 70","100 50","80 10","110 -10","110 -30","-20 -50","-30 -40","10 -10","-10 10","-30 -20","-50 30");

    // print_r($polygon);
    // Las últimas coordenadas tienen que ser las mismas que las primeras, para "cerrar el círculo"
    foreach($points as $key => $point) {
        echo "point " . ($key+1) . " ($point): " . $pointLocation->pointInPolygon($point, $polygon) . "<br>";
    }
    ?>

Upvotes: 0

Aroic
Aroic

Reputation: 479

The other answer here is probably your best bet, but if it doesn't work for whatever reason, it looks like you'll want to try a version of the Ray-casting algorithm. A few other users have tried that, and you can look here for reference. Good luck!

Upvotes: 1

Joey
Joey

Reputation: 1370

If you are just wanting to check if the polygon contains your point using Google maps you can try : Google Maps API

If you want to calculate it in PHP then your question is a duplicate of this: Check if Google Map Point is in polygon from PHP

Upvotes: 1

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