如何在给定点周围的给定点(纬度/经度)x米周围创建多边形(仅适用于我的情况)。这只是一个地理围栏的视觉表示,但我不需要计算一个点是否在地理围栏之外。我尝试使用下面的代码,但它创建一个矩形,而不是一个正方形,我甚至不知道1000米boudaries是否正确呈现。
How can I create a polygon(only a square in my case) around a given point(lat/lang) x meters around the given point. It's just a visual representation of a geofence but I dont need all the calculations whether a point is outside a geofence or not. I tried using the code below but its creating a rectangle instead of a square and I'm not even sure if the 1000 meter boudaries are being rendered correctly.
var map = new GMap2(document.getElementById("map_canvas")); map.setCenter(new GLatLng(37.4419, -122.1419), 13); map.addControl(new GSmallMapControl()); GEvent.addListener(map, 'click', function(overlay, latlng) { var lat = latlng.lat(); var lng = latlng.lng(); var height = 1000; //meters var width = 1000; //meters var polygon = new GPolygon( [ new GLatLng(lat + height / 2 * 90 / 10000000, lng + width / 2 * 90 / 10000000 / Math.cos(lat)), new GLatLng(lat - height / 2 * 90 / 10000000, lng + width / 2 * 90 / 10000000 / Math.cos(lat)), new GLatLng(lat - height / 2 * 90 / 10000000, lng - width / 2 * 90 / 10000000 / Math.cos(lat)), new GLatLng(lat + height / 2 * 90 / 10000000, lng - width / 2 * 90 / 10000000 / Math.cos(lat)), new GLatLng(lat + height / 2 * 90 / 10000000, lng + width / 2 * 90 / 10000000 / Math.cos(lat)) ], "#f33f00", 2, 1, "#ff0000", 0.2); map.addOverlay(polygon); });推荐答案
我移植了 PHP函数来计算距离某个任意距离和方位的位置已知的位置,到Javascript:
I ported this PHP function to calculate the location an arbitrary distance and bearing from a known location, to Javascript:
var EARTH_RADIUS_EQUATOR = 6378140.0; var RADIAN = 180 / Math.PI; function calcLatLong(longitude, lat, distance, bearing) { var b = bearing / RADIAN; var lon = longitude / RADIAN; var lat = lat / RADIAN; var f = 1/298.257; var e = 0.08181922; var R = EARTH_RADIUS_EQUATOR * (1 - e * e) / Math.pow( (1 - e*e * Math.pow(Math.sin(lat),2)), 1.5); var psi = distance/R; var phi = Math.PI/2 - lat; var arccos = Math.cos(psi) * Math.cos(phi) + Math.sin(psi) * Math.sin(phi) * Math.cos(b); var latA = (Math.PI/2 - Math.acos(arccos)) * RADIAN; var arcsin = Math.sin(b) * Math.sin(psi) / Math.sin(phi); var longA = (lon - Math.asin(arcsin)) * RADIAN; return new GLatLng (latA, longA); }我写了一个这个函数的实例,你可以检出( source )。
I have written a working example of this function that you can check out (source).
我使用毕达哥拉斯定理将平方的宽度翻译为半径,如果你想从中心使用一个简单的1000米半径,你可以这样做:
I use the Pythagorean Theorem to translate from a width of a square to a radius, if you want to use a simple 1000 meter radius from the center you can do that instead:
// this var radius = 1000; // instead of this var radius = (Math.sqrt (2 * (width * width))) / 2;更多推荐
在一个点周围绘制多边形x米
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