火星座标系 (GCJ-02) 与百度座标系 (BD-09) 的转换算法

本文系转载，原文地址http://blog.csdn.net/coolypf/article/details/8569813     （算法有效性未知）

算法代码如下，其中 bd_encrypt 将 GCJ-02 座标转换成 BD-09 座标， bd_decrypt 反之

C++语言描述

#include <math.h>  
  
const double x_pi = 3.14159265358979324 * 3000.0 / 180.0;  
  
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;  
}  
  
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);  
}