/// <summary>
/// 由空间直角坐标转换为椭球坐标。默认角度单位为度。
/// </summary>
/// <param name="x"></param>
/// <param name="y"></param>
/// <param name="z"></param>
/// <param name="a"></param>
/// <param name="e"></param>
/// <returns></returns>
public static GeoCoord XyzToGeoCoord(double x, double y, double z, double a, double e, AngleUnit angeUnit = AngleUnit.Degree)
{
double ee = e * e;
double lon = Math.Atan2(y, x);
double lat;
double height;
//iteration
double deltaZ = 0;
double sqrtXy = Math.Sqrt(x * x + y * y);
double tempLat = Math.Atan2(z, sqrtXy);//初始取值
lat = tempLat;
//if (Math.Abs(lat) > 80.0 * CoordConverter.DegToRadMultiplier)//lat=+-90,或height特大时，采用此算法更稳定（实际有待实验，保留both代码）
//{
int count = 0;//避免死循环
do
{
var sinLat = Sin(lat);
deltaZ = a * ee * sinLat / Math.Sqrt(1 - Math.Pow(e * sinLat, 2));
tempLat = lat;
lat = Math.Atan2(z + deltaZ, sqrtXy);
count++;
} while (Math.Abs(lat - tempLat) > 1E-12 || count < 20);
//}
//else//经典算法
//{
// do
// {
// double tanB = Math.Tan(lat);
// tempLat = lat;
// lat = Math.Atan2(z + a * ee * tanB / Math.Sqrt(1 + tanB * tanB * (1 - ee)), sqrtXy);
// } while (Math.Abs(lat - tempLat) > 1E-12);
//}
double n = a / Math.Sqrt(1 - Math.Pow(e * Sin(tempLat), 2));
//double height = Math.Sqrt(x * x + y * y + Math.Pow((z + deltaZ), 2)) - n;
height = sqrtXy / Cos(lat) - n;
//地心纬度
//double dixinLat = (1 - ee * n / (n + height)) * Math.Tan(lat);
//double dixinLatDeg = dixinLat * CoordConverter.RadToDegdMultiplier;
lon = AngularConvert.RadTo(lon, angeUnit);
lat = AngularConvert.RadTo(lat, angeUnit);
return(new GeoCoord(lon, lat, height));
}
/// <summary>
/// 站心坐标系到站心极坐标系。
/// </summary>
/// <param name="neu"></param>
/// <param name="unit">默认单位为度</param>
/// <returns></returns>
public static Polar NeuToPolar(NEU neu, AngleUnit unit = AngleUnit.Degree)
{
double r = neu.Length;
double a = Math.Atan2(neu.E, neu.N);
if (a < 0)//以北向为基准，顺时针，无负号
{
a += 2.0 * CoordConsts.PI;
}
double o = Math.Asin(neu.U / r);
if (unit != AngleUnit.Radian)
{
a = AngularConvert.RadTo(a, unit);
o = AngularConvert.RadTo(o, unit);
}
return(new Polar(r, a, o)
{
Unit = unit
});
}