public double Geocent_ep2; // 2nd eccentricity squared
//**************************************************************************
// METHODS
//**************************************************************************
// The function Set_Geocentric_Parameters receives the ellipsoid parameters
// as inputs and sets the corresponding state variables.
//
// a : Semi-major axis, in meters. (input)
// b : Semi-minor axis, in meters. (input)
public GEOCENT pj_Set_Geocentric_Parameters(double a, double b)
{
GEOCENT Error_Code = GEOCENT.NO_ERROR;
if (a <= 0.0)
{
Error_Code |= GEOCENT.A_ERROR;
}
if (b <= 0.0)
{
Error_Code |= GEOCENT.B_ERROR;
}
if (a < b)
{
Error_Code |= GEOCENT.A_LESS_B_ERROR;
}
if (Error_Code == 0)
{
Geocent_a = a;
Geocent_b = b;
Geocent_a2 = a * a;
Geocent_b2 = b * b;
Geocent_e2 = (Geocent_a2 - Geocent_b2) / Geocent_a2;
Geocent_ep2 = (Geocent_a2 - Geocent_b2) / Geocent_b2;
}
return(Error_Code);
}
// The function Convert_Geodetic_To_Geocentric converts geodetic coordinates
// (latitude, longitude, and height) to geocentric coordinates (X, Y, Z),
// according to the current ellipsoid parameters.
//
// Latitude : Geodetic latitude in radians (input)
// Longitude : Geodetic longitude in radians (input)
// Height : Geodetic height, in meters (input)
// X : Calculated Geocentric X coordinate, in meters. (output)
// Y : Calculated Geocentric Y coordinate, in meters. (output)
// Z : Calculated Geocentric Z coordinate, in meters. (output)
public GEOCENT pj_Convert_Geodetic_To_Geocentric(double Latitude, double Longitude, double Height,
out double X, out double Y, out double Z)
{
GEOCENT Error_Code = GEOCENT.NO_ERROR;
double Rn; // Earth radius at location
double Sin_Lat; // sin(Latitude)
double Sin2_Lat; // Square of sin(Latitude)
double Cos_Lat; // cos(Latitude)
// Don't blow up if Latitude is just a little out of the value
// range as it may just be a rounding issue. Also removed longitude
// test, it should be wrapped by cos() and sin(). NFW for PROJ.4, Sep/2001.
if (Latitude < -Proj.HALFPI && Latitude > -1.001 * Proj.HALFPI)
{
Latitude = -Proj.HALFPI;
}
else if (Latitude > Proj.HALFPI && Latitude < 1.001 * Proj.HALFPI)
{
Latitude = Proj.HALFPI;
}
else if ((Latitude < -Proj.HALFPI) || (Latitude > Proj.HALFPI))
{
Error_Code |= GEOCENT.LAT_ERROR; // Latitude out of range
}
if (Error_Code == 0) // no errors
{
if (Longitude > Proj.PI)
{
Longitude -= 2 * Proj.PI;
}
Sin_Lat = Math.Sin(Latitude);
Cos_Lat = Math.Cos(Latitude);
Sin2_Lat = Sin_Lat * Sin_Lat;
Rn = Geocent_a / (Math.Sqrt(1.0 - Geocent_e2 * Sin2_Lat));
X = (Rn + Height) * Cos_Lat * Math.Cos(Longitude);
Y = (Rn + Height) * Cos_Lat * Math.Sin(Longitude);
Z = ((Rn * (1 - Geocent_e2)) + Height) * Sin_Lat;
}
else
{
X = Y = Z = double.NaN;
}
return(Error_Code);
}
