如何使用 javascript 根据一组纬度和经度值计算面积？

Question

如何使用 javascript 根据一组纬度和经度值计算面积？

Vis*_*ide 1 javascript gps google-maps google-maps-api-3

我有一组从自己的数据库中提取的纬度和经度值。他们看起来像这样：

 // Define the LatLng coordinates for the polygon's path.
 var fizuliCoords = [
{lng:47.1648244,lat:39.6834661},
{lng:47.1653823,lat:39.6906634},
........there are 400-1200 lines...I only list 2
];
var bakuCoords = [
{lng:47.1648244,lat:39.6834661},
{lng:47.1653823,lat:39.6906634},
........there are 400-1200 lines...I only list 2
];

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有69个不同的行政区

我的项目是：

列出多边形
根据纬度/经度值集自动计算面积我是一个新手 - 所以请对我有耐心:)我可以从一个名为 Expert GPS 的程序中提取以平方公里为单位的面积，对于已知的 shpaes 没有任何问题，但我需要一个自动化脚本。谢谢.....我很抱歉，第一次来:)

好的，

     <!DOCTYPE html>
      <html>
   <head>
    <meta name="viewport" content="initial-scale=1.0, user-scalable=no">
     <meta charset="utf-8">
     <title>ttttt</title>
     <style>
        html, body {
        height: 100%;
        margin: 0;
        padding: 0;
      }
 /*   #map is the div that places map on the html page*/
      #map {
        height: 100%;
       }
/*    end of #map */      
    </style>
  </head>
  <body>
    <div id="map"></div>
     <script>
  // This example creates a simple polygon representing the shusha Region.
  //the initMapfunction places the map on the page
   function initMap() {
    var map = new google.maps.Map(document.getElementById('map'), {
    zoom: 8,
    center: {lat: 40.352310, lng: 47.999462},       
    mapTypeId: google.maps.MapTypeId.TERRAIN
  });
//end oof initMap function
//------------------------------------------------------------------
// Define the LatLng coordinates for the Shusha polygon's path.
var shushaCoords = [
{lng:46.5852069,lat:39.7918524},
{lng:46.5810012,lat:39.789016},
{lng:46.5800569,lat:39.7812995},
{lng:46.5741348,lat:39.7757586},
{lng:46.5720748,lat:39.7722619},
{lng:46.571817,lat:39.763026}
];
// Define the LatLng coordinates for the Khojavend polygon's path.
var khojavendCoords = [
{lng:46.6707802,lat:39.5735368},
{lng:46.6646003,lat:39.5704934},
{lng:46.6628837,lat:39.5675823}
];
// Define the LatLng coordinates for the Zangilan polygon's path.
var xocaliCoords = [
{lng:46.6195822,lat:39.233882},
{lng:46.6161489,lat:39.232918},
{lng:46.6094971,lat:39.2322199},
{lng:46.6076088,lat:39.2318542},
{lng:46.6009998,lat:39.229494}
];
**and so on for 69 more areas then come the polygons**

**// Construct the xocali polygon.**
var xocali = new google.maps.Polygon({
    map: map,
    paths: xocaliCoords,
    strokeColor: '#000000',
    strokeOpacity: 0.5,
    strokeWeight: 2,
    fillColor: '#00CCFF',
    fillOpacity: 0.15
  });
**//and then 68 more** 
// Add a listener for the julfa mouseover/mouseout event.
google.maps.event.addListener(julfa ,'mouseover',function(){
this.setOptions({fillColor: "#00FF00"});
}); 
**//here I would like to add a popup where the AREA will be calculated**
google.maps.event.addListener(julfa ,'mouseout',function(){
this.setOptions({fillColor: "#00CCFF"});
});  
//and then 68 more sets of listeners
}
 </script>
<!--end of mapping script-->
<!--the script below is the googleAPI browser script, if i need to display on     the server - must change to Server API code.-->
    <script async defer src="https://maps.googleapis.com/maps/api/js?    key=xxxxxxxxxxxxxxxxx&signed_in=true&callback=initMap"></script>
  </body>
</html>

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所以我这里有 3 个问题： 1. 能够构建一个公式，根据每个多边形的 lat lng 值计算面积 2. 在弹出窗口中完成此操作 3. 可以使用外部 .js 文件

Answer 1

geo*_*zip 5

Google Maps Javascript API几何库包含以下方法computeArea：

计算区域（路径：数组|MVCArray，半径？：数字）

返回值：数字

返回闭合路径的面积。计算面积使用与半径相同的单位。半径默认为地球半径（以米为单位），在这种情况下，面积以平方米为单位。

参考

我的建议是创建一个子例程，将多边形添加到地图中，并使用鼠标悬停/鼠标悬停/单击侦听器完成：

function addPolygon(points, name, bounds, map) {
    var path = [];
    var polybounds = new google.maps.LatLngBounds();
    for (var i = 0; i < points.length; i++) {
        path.push(new google.maps.LatLng(points[i].lat, points[i].lng));
        bounds.extend(path[path.length - 1]);
        polybounds.extend(path[path.length - 1]);
        var m = new google.maps.Marker({
            position: path[path.length - 1],
            // map: map,
            title: name + i + " " + path[path.length - 1].toUrlValue(6),
            icon: {
                url: "https://maps.gstatic.com/intl/en_us/mapfiles/markers2/measle_blue.png",
                size: new google.maps.Size(7, 7),
                anchor: new google.maps.Point(3.5, 3.5)
            }
        });
    }
    var polygon = new google.maps.Polygon({
        paths: path,
        strokeColor: '#000000',
        strokeOpacity: 0.5,
        strokeWeight: 2,
        fillColor: '#00CCFF',
        fillOpacity: 0.15,
        map: map,
        bounds: polybounds
    });
    polygons.push(polygon);
    google.maps.event.addListener(polygon, 'click', function (evt) {
        infowindow.setContent(name + " area: " + google.maps.geometry.spherical.computeArea(polygon.getPath()).toFixed(2) + " square meters");
        infowindow.setPosition(evt.latLng);
        infowindow.open(map);
    });
    google.maps.event.addListener(polygon, 'mouseover', function () {
        this.setOptions({
            fillColor: "#00FF00"
        });
    });
    google.maps.event.addListener(polygon, 'mouseout', function () {
        this.setOptions({
            fillColor: "#00CCFF"
        });
    });
}

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代码片段：

function addPolygon(points, name, bounds, map) {
    var path = [];
    var polybounds = new google.maps.LatLngBounds();
    for (var i = 0; i < points.length; i++) {
        path.push(new google.maps.LatLng(points[i].lat, points[i].lng));
        bounds.extend(path[path.length - 1]);
        polybounds.extend(path[path.length - 1]);
        var m = new google.maps.Marker({
            position: path[path.length - 1],
            // map: map,
            title: name + i + " " + path[path.length - 1].toUrlValue(6),
            icon: {
                url: "https://maps.gstatic.com/intl/en_us/mapfiles/markers2/measle_blue.png",
                size: new google.maps.Size(7, 7),
                anchor: new google.maps.Point(3.5, 3.5)
            }
        });
    }
    var polygon = new google.maps.Polygon({
        paths: path,
        strokeColor: '#000000',
        strokeOpacity: 0.5,
        strokeWeight: 2,
        fillColor: '#00CCFF',
        fillOpacity: 0.15,
        map: map,
        bounds: polybounds
    });
    polygons.push(polygon);
    google.maps.event.addListener(polygon, 'click', function (evt) {
        infowindow.setContent(name + " area: " + google.maps.geometry.spherical.computeArea(polygon.getPath()).toFixed(2) + " square meters");
        infowindow.setPosition(evt.latLng);
        infowindow.open(map);
    });
    google.maps.event.addListener(polygon, 'mouseover', function () {
        this.setOptions({
            fillColor: "#00FF00"
        });
    });
    google.maps.event.addListener(polygon, 'mouseout', function () {
        this.setOptions({
            fillColor: "#00CCFF"
        });
    });
}

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var infowindow = new google.maps.InfoWindow();
var polygons = [];

function initialize() {
  var map = new google.maps.Map(
    document.getElementById("map_canvas"), {
      center: new google.maps.LatLng(37.4419, -122.1419),
      zoom: 13,
      mapTypeId: google.maps.MapTypeId.ROADMAP
    });
  var bounds = new google.maps.LatLngBounds();
  addPolygon(bakuCoords, "baku", bounds, map);
  addPolygon(fizuliCoords, "fizuli", bounds, map);

  map.fitBounds(polygons[0].bounds);
}
google.maps.event.addDomListener(window, "load", initialize);

function addPolygon(points, name, bounds, map) {
    var path = [];
    var polybounds = new google.maps.LatLngBounds();
    for (var i = 0; i < points.length; i++) {
      path.push(new google.maps.LatLng(points[i].lat, points[i].lng));
      bounds.extend(path[path.length - 1]);
      polybounds.extend(path[path.length - 1]);
    }
    var polygon = new google.maps.Polygon({
      paths: path,
      strokeColor: '#000000',
      strokeOpacity: 0.5,
      strokeWeight: 2,
      fillColor: '#00CCFF',
      fillOpacity: 0.15,
      map: map,
      bounds: polybounds
    });
    polygons.push(polygon);
    google.maps.event.addListener(polygon, 'click', function(evt) {
      infowindow.setContent(name + " area: " + google.maps.geometry.spherical.computeArea(polygon.getPath()).toFixed(2) + " square meters");
      infowindow.setPosition(evt.latLng);
      infowindow.open(map);
    });
    google.maps.event.addListener(polygon, 'mouseover', function() {
      this.setOptions({
        fillColor: "#00FF00"
      });
    });
    google.maps.event.addListener(polygon, 'mouseout', function() {
      this.setOptions({
        fillColor: "#00CCFF"
      });
    });
  }
  // Define the LatLng coordinates for the polygon's path.
var fizuliCoords = [{
  lng: 47.1648244,
  lat: 39.6834661
}, {
  lng: 47.1653823,
  lat: 39.6906634
}, {
  lng: 47.16,
  lat: 39.68
}, {
  lng: 47.163,
  lat: 39.684
}];
var bakuCoords = [{
  lng: 47.1648244,
  lat: 39.6834661
}, {
  lng: 47.1653823,
  lat: 39.6906634
}, {
  lng: 47.165,
  lat: 39.692
}, {
  lng: 47.166,
  lat: 39.692
}];

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html,
body,
#map_canvas {
  height: 100%;
  width: 100%;
  margin: 0px;
  padding: 0px
}

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