/// <summary>
/// Calling this method will convert from the passed value to the OSGB36 convertor
/// </summary>
/// <param name="pHorizontal">The point on the horizontal axis (easting or latitude)</param>
/// <param name="pVertical">The point on the vertical axis (northing or longtitude)</param>
/// <param name="pHeight">The height to be converted</param>
/// <returns>The location as a OSGB36 coordinate</returns>
private ICoordinate InternalCalculate(double pHorizontal, double pVertical, double pHeight)
{
double lat = mCoordinateSupport.DegreeesToRadians(pVertical);
double lon = mCoordinateSupport.DegreeesToRadians(pHorizontal);
double ht = pHeight;
double a = OSGB35Constants.a;
a *= OSGB35Constants.f0;
double b = OSGB35Constants.b;
b *= OSGB35Constants.f0;
double n = (a - b) / (a + b);
double e2 = ((a * a) - (b * b)) / (a * a);
double nu = (a / Math.Pow(1 - e2 * Math.Pow(Math.Sin(lat), 2.0), 0.5));
double rho = ((a * (1 - e2)) / Math.Pow(1 - e2 * Math.Pow(Math.Sin(lat), 2.0), 1.5));
double n2 = (nu / rho) - 1;
double dLat = lat - OSGB35Constants.lat0; // difference in latitude
double sLat = lat + OSGB35Constants.lat0; // sum of latitude
double M = MeridianArc.ComputeMeridanArc(dLat, sLat, n, b);
double P = lon - OSGB35Constants.lon0; // difference in longitude
// The following are taken from [1] pp10-11
double I = M + OSGB35Constants.n0;
double II = (nu / 2) * Math.Sin(lat) * Math.Cos(lat);
double III = (nu / 24) * Math.Sin(lat) * Math.Pow(Math.Cos(lat), 3.0) * (5 - Math.Pow(Math.Tan(lat), 2.0) + (9 * n2));
double IIIA = (nu / 720) * Math.Sin(lat) * Math.Pow(Math.Cos(lat), 5.0) *
(61 - (58 * Math.Pow(Math.Tan(lat), 2.0)) + Math.Pow(Math.Tan(lat), 4.0));
double IV = nu * Math.Cos(lat);
double V = (nu / 6) * Math.Pow(Math.Cos(lat), 3.0) * ((nu / rho) - Math.Pow(Math.Tan(lat), 2.0));
double VI = (nu / 120) * Math.Pow(Math.Cos(lat), 5.0) * (5 - (18 * Math.Pow(Math.Tan(lat), 2.0)) +
Math.Pow(Math.Tan(lat), 4.0) + (14 * n2) - (58 * Math.Pow(Math.Tan(lat), 2.0) * n2));
double y = I + (Math.Pow(P, 2.0) * II) + (Math.Pow(P, 4.0) * III) + (Math.Pow(P, 6.0) * IIIA);
double x = OSGB35Constants.e0 + (P * IV) + (Math.Pow(P, 3.0) * V) + (Math.Pow(P, 5.0) * VI);
Shift s = (Shift)mShifts.CalculateShift(x, y);
double lLat = x + s.Easting;
double lLon = y + s.Northing;
double lHeight = pHeight - s.Height;
EastingNorthing x1 = new EastingNorthing(lLat, lLon, lHeight);
return(x1);
}
/// <summary>
/// Calling this method will convert from the passed value to the LatLon
/// </summary>
/// <param name="pHorizontal">The point on the horizontal axis (easting or latitude)</param>
/// <param name="pVertical">The point on the vertical axis (northing or longtitude)</param>
/// <param name="pHeight">The height to be converted</param>
/// <returns>The location as a LatLon coordinate</returns>
private ICoordinate InternalCalculate(double pHorizontal, double pVertical, double pHeight)
{
double eS = 0, nS = 0;
double ht_dif = 0;
double E = 0, N = 0;
Shift s = (Shift)mShifts.CalculateShift(pHorizontal, pVertical);
eS = s.Easting;
nS = s.Northing;
ht_dif = Math.Round(s.Height, 3);
double diff = 0, diffn = 0, NeweS = 0, NewnS = 0;
int iterations = 0;
do
{
E = pHorizontal - eS; // use shifts to calculate OSGRS80 Grid coordinates
N = pVertical - nS;
s = (Shift)mShifts.CalculateShift(pHorizontal, pVertical);
NeweS = s.Easting;
NewnS = s.Northing;
ht_dif = s.Height;
diff = NeweS - eS;
diffn = NewnS - nS;
eS = NeweS;
nS = NewnS;
iterations = iterations + 1;
} while ((iterations < 30) && ((Math.Abs(diff) > 0.00001)) || (Math.Abs(diffn) > 0.00001));
double a = OSGB35Constants.a;
a *= OSGB35Constants.f0;
double b = OSGB35Constants.b;
b *= OSGB35Constants.f0;
double n = (a - b) / (a + b);
double e2 = ((a * a) - (b * b)) / (a * a);
double latEst = ((N - OSGB35Constants.n0) / a) + OSGB35Constants.lat0;
double latNew, dLat, sLat, M;
iterations = 0;
do
{
dLat = latEst - OSGB35Constants.lat0; // difference in latitude
sLat = latEst + OSGB35Constants.lat0; // sum of latitude
M = MeridianArc.ComputeMeridanArc(dLat, sLat, n, b);
latNew = ((N - OSGB35Constants.n0 - M) / a) + latEst;
latEst = latNew;
diff = N - OSGB35Constants.n0 - M;
} while ((iterations++ < 30) && (diff > 0.000001));
double nu = (a / Math.Pow(1 - e2 * Math.Pow(Math.Sin(latEst), 2.0), 0.5));
double rho = ((a * (1 - e2)) / Math.Pow(1 - e2 * Math.Pow(Math.Sin(latEst), 2.0), 1.5));
double n2 = (nu / rho) - 1;
double VII = Math.Tan(latEst) / (2 * nu * rho);
double VIII = (Math.Tan(latEst) / (24 * rho * Math.Pow(nu, 3.0))) * (5 + (3 * Math.Pow(Math.Tan(latEst), 2.0)) +
n2 - (9 * Math.Pow(Math.Tan(latEst), 2.0) * n2));
double IX = (Math.Tan(latEst) / (720 * rho * Math.Pow(nu, 5.0))) * (61 + (90 * Math.Pow(Math.Tan(latEst), 2.0)) +
(45 * Math.Pow(Math.Tan(latEst), 4.0)));
double X = 1 / (Math.Cos(latEst) * nu);
double XI = (1 / (6 * (Math.Cos(latEst) * Math.Pow(nu, 3.0))) * ((nu / rho) + (2 * Math.Pow(Math.Tan(latEst), 2.0))));
double XII = (1 / (120 * (Math.Cos(latEst) * Math.Pow(nu, 5.0))) * (5 + (28 * Math.Pow(Math.Tan(latEst), 2.0)) + (24 * Math.Pow(Math.Tan(latEst), 4.0))));
double XIIA = (1 / (5040 * (Math.Cos(latEst) * Math.Pow(nu, 7.0))) * (61 + (662 * Math.Pow(Math.Tan(latEst), 2.0)) +
(1320 * Math.Pow(Math.Tan(latEst), 4.0)) + (720 * Math.Pow(Math.Tan(latEst), 6.0))));
double y = E - OSGB35Constants.e0;
double k1 = latEst - (y * y * VII) + (Math.Pow(y, 4.0) * VIII) - (Math.Pow(y, 6.0) * IX);
double k2 = OSGB35Constants.lon0 + (y * X) - (Math.Pow(y, 3.0) * XI) + (Math.Pow(y, 5.0) * XII) - (Math.Pow(y, 7.0) * XIIA);
double k3 = pHeight + ht_dif;
// [TestCase(49.92226393730, -6.29977752014, 100.000, 91492.146, 11318.804, 46.519)]
double xr1 = mCoordinateSupport.RadiansToDegrees(k1);
double xr2 = mCoordinateSupport.RadiansToDegrees(k2);
return(new LatLon(xr1, xr2, k3));
}
