计算在谷歌地图上绘制的多边形的面积

Question

我正在寻找一种精确的算法或服务来计算地球上的表面积,其中点数是根据GPS坐标计算的.

我正在使用谷歌地图Api版本3,并根据记录的坐标绘制多边形,但我不认为计算多边形面积的标准方法将考虑斜率(山丘).我需要为这样的东西做轮廓吗？

是否有任何第三方服务可能是ArcGis或其他考虑到斜坡的服务.

Answer 1

是的,这绝对是可能的.这里有一个带示例代码的快速教程:

https://web.archive.org/web/20130301120148/http://geojason.info/demos/line-length-polygon-area-google-maps-v3

相关部分是这样的:

google.maps.geometry.spherical.computeArea(yourPolygon.getPath());

官方文件:

http://code.google.com/apis/maps/documentation/javascript/reference.html#spherical

Answer 2

布拉德的回答

google.maps.geometry.spherical.computeArea(yourPolygon.getPath());

是正确的,但要注意,它只适用于不自相交的多边形.当多边形开始自相交时,事情就会发生可怕的错误.您可以使用Brad给出的链接http://geojason.info/demos/line-length-polygon-area-google-maps-v3/进行尝试.只需绘制4-5条相交线并开始使用顶点.面积计算肯定会出错.

如果你不相信,这是一个例子:

   var map;

    google.maps.visualRefresh = true;

    google.maps.event.addDomListener(window, 'load', initialize);

    function initialize() {
        var mapOptions = {
            center : new google.maps.LatLng(55.874, -4.287),
            zoom : 16,
            mapTypeId : google.maps.MapTypeId.ROADMAP
        };
        map = new google.maps.Map(document.getElementById("map-canvas"), mapOptions)

        drawExample();
    }

    function drawExample() {
        var pathLeft = [new google.maps.LatLng(55.874, -4.292),
            new google.maps.LatLng(55.875, -4.292),
            new google.maps.LatLng(55.875, -4.290),
            new google.maps.LatLng(55.876, -4.290),
            new google.maps.LatLng(55.876, -4.291),
            new google.maps.LatLng(55.874, -4.291)]

        var polygonLeft = new google.maps.Polygon({
            path : pathLeft,
            map: map
        });

        var areaLeft = google.maps.geometry.spherical.computeArea(polygonLeft.getPath());

        var pathRight = [new google.maps.LatLng(55.874, -4.282),
            new google.maps.LatLng(55.875, -4.282),
            new google.maps.LatLng(55.875, -4.280),
            new google.maps.LatLng(55.8753, -4.2807),
            new google.maps.LatLng(55.876, -4.281),
            new google.maps.LatLng(55.874, -4.281)]

        var polygonRight = new google.maps.Polygon({
            path : pathRight,
            map: map
        });

        var areaRight = google.maps.geometry.spherical.computeArea(polygonRight.getPath());

        console.log("areaLeft: " + areaLeft + "\nareaRight: " + areaRight);
    }

错误报告http://code.google.com/p/gmaps-api-issues/issues/detail?id=5624&colspec=ID%20Type%20Status%20Introduced%20Fixed%20Summary%20Stars%20ApiType%20Internal&start=700#makechanges