WGS-84坐标系：全球定位系统使用，GPS、北斗等
GCJ-02坐标系：中国地区使用，由WGS-84偏移而来
BD-09坐标系：百度专用，由GCJ-02偏移而来
(PS:源于项目需求，本来是想读图片的经纬度显示在百度离线地图上的。后来发现定位偏差太大，仔细一想，原来是图片和百度使用的坐标系不一样。
计算转换部分
public class GPSChange
{
private const double pi = 3.14159265358979324;
private const double x_pi = 3.14159265358979324 * 3000.0 / 180.0; //克拉索天斯基椭球体参数值
private const double a = 6378245.0;
//第一偏心率
private const double ee = 0.00669342162296594323; /// <summary>
/// GCJ-02转换BD-09
/// </summary>
/// <param name="gg_lat">纬度</param>
/// <param name="gg_lon">经度</param>
/// <returns></returns>
public static GPSPoint GCJ02_to_BD09(double gg_lat, double gg_lon)
{
GPSPoint point = new GPSPoint();
double x = gg_lon, y = gg_lat;
double z = Math.Sqrt(x * x + y * y) + 0.00002 * Math.Sin(y * x_pi);
double theta = Math.Atan2(y, x) + 0.000003 * Math.Cos(x * x_pi);
double bd_lon = z * Math.Cos(theta) + 0.0065;
double bd_lat = z * Math.Sin(theta) + 0.006;
point.SetLat(bd_lat);
point.SetLng(bd_lon);
return point;
} /// <summary>
/// BD-09转换GCJ-02
/// </summary>
/// <param name="bd_lat">纬度</param>
/// <param name="bd_lon">经度</param>
/// <returns></returns>
public static GPSPoint BD09_to_GCJ02(double bd_lat, double bd_lon)
{
GPSPoint point = new GPSPoint();
double x = bd_lon - 0.0065, y = bd_lat - 0.006;
double z = Math.Sqrt(x * x + y * y) - 0.00002 * Math.Sin(y * x_pi);
double theta = Math.Atan2(y, x) - 0.000003 * Math.Cos(x * x_pi);
double gg_lon = z * Math.Cos(theta);
double gg_lat = z * Math.Sin(theta);
point.SetLat(gg_lat);
point.SetLng(gg_lon);
return point;
} /// <summary>
/// WGS-84转换GCJ-02
/// </summary>
/// <param name="wgLat">纬度</param>
/// <param name="wgLon">经度</param>
/// <returns></returns>
public static GPSPoint WGS84_to_GCJ02(double wgLat, double wgLon)
{
GPSPoint point = new GPSPoint();
if (OutOfChina(wgLat, wgLon))
{
point.SetLat(wgLat);
point.SetLng(wgLon);
return point;
}
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 = - ee * magic * magic;
double sqrtMagic = Math.Sqrt(magic);
dLat = (dLat * 180.0) / ((a * ( - ee)) / (magic * sqrtMagic) * pi);
dLon = (dLon * 180.0) / (a / sqrtMagic * Math.Cos(radLat) * pi);
double lat = wgLat + dLat;
double lon = wgLon + dLon;
point.SetLat(lat);
point.SetLng(lon);
return point;
} public static void Transform(double wgLat, double wgLon, double[] latlng)
{
if (OutOfChina(wgLat, wgLon))
{
latlng[] = wgLat;
latlng[] = 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 = - ee * magic * magic;
double sqrtMagic = Math.Sqrt(magic);
dLat = (dLat * 180.0) / ((a * ( - ee)) / (magic * sqrtMagic) * pi);
dLon = (dLon * 180.0) / (a / sqrtMagic * Math.Cos(radLat) * pi);
latlng[] = wgLat + dLat;
latlng[] = wgLon + dLon;
} private 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;
} private 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) + * Math.Sin(y * pi / 30.0)) * 2.0 / 3.0;
return ret;
} private 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;
} }
基础类
public class GPSPoint
{
private double lat;// 纬度
private double lng;// 经度 public GPSPoint()
{
} public GPSPoint(double lng, double lat)
{
this.lng = lng;
this.lat = lat;
} public double GetLat()
{
return lat;
}
public void SetLat(double lat)
{
this.lat = lat;
}
public double GetLng()
{
return lng;
}
public void SetLng(double lng)
{
this.lng = lng;
} }