主流地图 坐标系转换，百度、腾讯、高德等

在我国，为了国家安全，电子地图不可以使用地球坐标系WGS84，必须经过偏转。面前主流的几款地图都有其对应的坐标系。

例如

高德、腾讯、图灵、阿里地图等都是 GCJ-02坐标系（也称火星坐标系）

而百度则使用BD-09坐标系。

那么这3个常用坐标系直接如何转换呢。

参照这个连接我总结了一下。http://blog.csdn.net/meegomeego/article/details/39927017

1，GCJ-02(火星)转BD-09（百度地图）

逻辑：

void bd_encrypt(double gg_lat, double gg_lon, double &bd_lat, double &bd_lon){    double x = gg_lon, y = gg_lat;    double z = sqrt(x * x + y * y) + 0.00002 * sin(y * x_pi);    double theta = atan2(y, x) + 0.000003 * cos(x * x_pi);    bd_lon = z * cos(theta) + 0.0065;    bd_lat = z * sin(theta) + 0.006;}

javaScript语法翻译：

function MapabcEncryptToBdmap(gg_lat, gg_lon)   {     var point=new Object(); var x_pi = 3.14159265358979324 * 3000.0 / 180.0;     var x = new Number(gg_lon);     var y = new Number(gg_lat);       var z =  Math.sqrt(x * x + y * y) + 0.00002 * Math.sin(y * x_pi);       var theta = Math.atan2(y, x) + 0.000003 * Math.cos(x * x_pi);       var bd_lon = z * Math.cos(theta) + 0.0065;       var bd_lat = z * Math.sin(theta) + 0.006;      point.lng=bd_lon;     point.lat=bd_lat;     //alert("-1:"+point.lng+","+point.lat);     return point; }  

2，BD-09（百度地图）转 GCJ-02(火星)

逻辑：

void bd_decrypt(double bd_lat, double bd_lon, double &gg_lat, double &gg_lon){    double x = bd_lon - 0.0065, y = bd_lat - 0.006;    double z = sqrt(x * x + y * y) - 0.00002 * sin(y * x_pi);    double theta = atan2(y, x) - 0.000003 * cos(x * x_pi);    gg_lon = z * cos(theta);    gg_lat = z * sin(theta);}

javaScript语法翻译

 function BdmapEncryptToMapabc(bd_lat,bd_lon) { var point=new Object(); var x_pi = 3.14159265358979324 * 3000.0 / 180.0;     var x = new Number(bd_lon - 0.0065);     var y = new Number(bd_lat - 0.006);     var z = Math.sqrt(x * x + y * y) - 0.00002 * Math.sin(y * x_pi);     var theta = Math.atan2(y, x) - 0.000003 * Math.cos(x * x_pi);     var Mars_lon = z * Math.cos(theta);     var Mars_lat = z * Math.sin(theta);     point.lng=Mars_lon;     point.lat=Mars_lat;     return point; }

3，WGS84(地球坐标系)转BD-09(百度坐标系)

function GPSToBaidu(lngX,latY){var gps_point=new BMap.Point(lngX,latY);BMap.Convertor.translate(gps_point,0,function(bd_point){   alert("lng:"+bd_point.lng+" lat:"+bd_point.lat);});}

4，WGS84(地球坐标系)转GCJ-02(火星坐标系)

逻辑C#版（干活了，没时间了）：

using System;namespace Navi{    class EvilTransform    {        const double pi = 3.14159265358979324;        //        // Krasovsky 1940        //        // a = 6378245.0, 1/f = 298.3        // b = a * (1 - f)        // ee = (a^2 - b^2) / a^2;        const double a = 6378245.0;        const double ee = 0.00669342162296594323;        //        // World Geodetic System ==> Mars Geodetic System        public static void transform(double wgLat, double wgLon, out double mgLat, out double mgLon)        {            if (outOfChina(wgLat, wgLon))            {                mgLat = wgLat;                mgLon = wgLon;                return;            }            double dLat = transformLat(wgLon - 105.0, wgLat - 35.0);            double dLon = transformLon(wgLon - 105.0, wgLat - 35.0);            double radLat = wgLat / 180.0 * pi;            double magic = Math.Sin(radLat);            magic = 1 - ee * magic * magic;            double sqrtMagic = Math.Sqrt(magic);            dLat = (dLat * 180.0) / ((a * (1 - ee)) / (magic * sqrtMagic) * pi);            dLon = (dLon * 180.0) / (a / sqrtMagic * Math.Cos(radLat) * pi);            mgLat = wgLat + dLat;            mgLon = wgLon + dLon;        }        static bool outOfChina(double lat, double lon)        {            if (lon < 72.004 || lon > 137.8347)                return true;            if (lat < 0.8293 || lat > 55.8271)                return true;            return false;        }        static double transformLat(double x, double y)        {            double ret = -100.0 + 2.0 * x + 3.0 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * Math.Sqrt(Math.Abs(x));            ret += (20.0 * Math.Sin(6.0 * x * pi) + 20.0 * Math.Sin(2.0 * x * pi)) * 2.0 / 3.0;            ret += (20.0 * Math.Sin(y * pi) + 40.0 * Math.Sin(y / 3.0 * pi)) * 2.0 / 3.0;            ret += (160.0 * Math.Sin(y / 12.0 * pi) + 320 * Math.Sin(y * pi / 30.0)) * 2.0 / 3.0;            return ret;        }        static double transformLon(double x, double y)        {            double ret = 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * Math.Sqrt(Math.Abs(x));            ret += (20.0 * Math.Sin(6.0 * x * pi) + 20.0 * Math.Sin(2.0 * x * pi)) * 2.0 / 3.0;            ret += (20.0 * Math.Sin(x * pi) + 40.0 * Math.Sin(x / 3.0 * pi)) * 2.0 / 3.0;            ret += (150.0 * Math.Sin(x / 12.0 * pi) + 300.0 * Math.Sin(x / 30.0 * pi)) * 2.0 / 3.0;            return ret;        }    }}

关于准确性，BD-09和GCJ-02我验证过了，误差在10米左右，可以接收。WGS-84和其他坐标系直接的转换待完善和验证。