/// <summary>
/// Used to convert latlon from degrees to radians
/// </summary>
/// <param name="latLon">Latitude and Longidute object in degrees</param>
/// <returns>Latitude and Longidute object in radians</returns>
private LatLon ToRadians(LatLon latLon)
{
return new LatLon
{
Latitude = latLon.Latitude * Math.PI / 180,
Longitude = latLon.Longitude * Math.PI / 180,
};
}
/// <summary>
/// Used to convert latlon from radians to degrees
/// <param name="latLon">Latitude and Longidute object in radians</param>
/// <returns>Latitude and Longidute object in degrees</returns>
/// </summary>
private LatLon ToDegrees(LatLon latLon)
{
return new LatLon
{
Latitude = latLon.Latitude * 180 / Math.PI,
Longitude = latLon.Longitude * 180 / Math.PI,
};
}
/// <summary>
/// Abridged Molodensky transformation between 2 datums
/// </summary>
/// <param name="input"></param>
/// <param name="from"></param>
/// <param name="to"></param>
/// <returns></returns>
private LatLon Molodensky(LatLon input, string from, string to)
{
// from->WGS84 - to->WGS84 = from->WGS84 + WGS84->to = from->to
double dX = Datums[from].DeltaX - Datums[to].DeltaX;
double dY = Datums[from].DeltaY - Datums[to].DeltaY;
double dZ = Datums[from].DeltaZ - Datums[to].DeltaZ;
double slat = Math.Sin(input.Latitude);
double clat = Math.Cos(input.Latitude);
double slon = Math.Sin(input.Longitude);
double clon = Math.Cos(input.Longitude);
double ssqlat = slat * slat;
//dlat = ((-dx * slat * clon - dy * slat * slon + dz * clat)
// + (da * rn * from_esq * slat * clat / from_a)
// + (df * (rm * adb + rn / adb )* slat * clat))
// / (rm + from.h);
double from_f = Datums[from].Flatenning;
double df = Datums[to].Flatenning - from_f;
double from_a = Datums[from].EquatorialEarthRadius;
double da = Datums[to].EquatorialEarthRadius - from_a;
double from_esq = Datums[from].EccentricitySquared;
double adb = 1.0 / (1.0 - from_f);
double rn = from_a / Math.Sqrt(1 - from_esq * ssqlat);
double rm = from_a * (1 - from_esq) / Math.Pow((1 - from_esq * ssqlat), 1.5);
double from_h = 0.0; // we're flat!
double dlat = (-dX * slat * clon - dY * slat * slon + dZ * clat
+ da * rn * from_esq * slat * clat / from_a +
+df * (rm * adb + rn / adb) * slat * clat) / (rm + from_h);
// dlon = (-dx * slon + dy * clon) / ((rn + from.h) * clat);
double dlon = (-dX * slon + dY * clon) / ((rn + from_h) * clat);
// result lat (radians)
return new LatLon
{
Latitude = input.Latitude + dlat,
Longitude = input.Longitude + dlon
};
}
/// <summary>
/// Lat/Lon to Local Grid conversion
/// </summary>
/// <param name="latLon"></param>
/// <param name="from"></param>
/// <param name="to"></param>
/// <returns></returns>
private NorthEast LatLon2Grid(LatLon latLon, string from, string to)
{
// Datum data for Lat/Lon to TM conversion
double a = Datums[from].EquatorialEarthRadius;
double e = Datums[from].Eccentricity; // sqrt(esq);
double b = Datums[from].PolarEarthRadius;
double lat = latLon.Latitude;
double lon = latLon.Longitude;
double slat1 = Math.Sin(lat);
double clat1 = Math.Cos(lat);
double clat1sq = clat1 * clat1;
double tanlat1sq = slat1 * slat1 / clat1sq;
double e2 = e * e;
double e4 = e2 * e2;
double e6 = e4 * e2;
double eg = (e * a / b);
double eg2 = eg * eg;
double l1 = 1 - e2 / 4 - 3 * e4 / 64 - 5 * e6 / 256;
double l2 = 3 * e2 / 8 + 3 * e4 / 32 + 45 * e6 / 1024;
double l3 = 15 * e4 / 256 + 45 * e6 / 1024;
double l4 = 35 * e6 / 3072;
double M = a * (l1 * lat - l2 * Math.Sin(2 * lat) + l3 * Math.Sin(4 * lat) - l4 * Math.Sin(6 * lat));
//double rho = a*(1-e2) / pow((1-(e*slat1)*(e*slat1)),1.5);
double nu = a / Math.Sqrt(1 - (e * slat1) * (e * slat1));
double p = lon - Grids[to].CentralLongitude;
double k0 = Grids[to].ScaleFactor;
// y = northing = K1 + K2p2 + K3p4, where
double K1 = M * k0;
double K2 = k0 * nu * slat1 * clat1 / 2;
double K3 = (k0 * nu * slat1 * clat1 * clat1sq / 24) * (5 - tanlat1sq + 9 * eg2 * clat1sq + 4 * eg2 * eg2 * clat1sq * clat1sq);
// ING north
double Y = K1 + K2 * p * p + K3 * p * p * p * p - Grids[to].FalseNorthing;
// x = easting = K4p + K5p3, where
double K4 = k0 * nu * clat1;
double K5 = (k0 * nu * clat1 * clat1sq / 6) * (1 - tanlat1sq + eg2 * clat1 * clat1);
// ING east
double X = K4 * p + K5 * p * p * p + Grids[to].FalseEasting;
// final rounded results
return new NorthEast
{
North = (int)(Y + 0.5),
East = (int)(X + 0.5),
};
}
/// <summary>
/// WGS84 to Israel New Grid (ITM) conversion
/// </summary>
/// <param name="latLon">Latitide and Longitude in WGS84</param>
/// <returns>North East Coordinates in ITM grid</returns>
public NorthEast Wgs84ToItm(LatLon latLon)
{
// 1. Molodensky WGS84 -> GRS80
var latLon80 = Molodensky(ToRadians(latLon), WGS84, GRS80);
// 2. Lat/Lon (GRS80) -> Local Grid (ITM)
return LatLon2Grid(latLon80, GRS80, ITM);
}
/// <summary>
/// WGS84 to Israel Old Grid (ICS) conversion
/// </summary>
/// <param name="latLon">Latitide and Longitude in WGS84</param>
/// <returns>North East Coordinates in ICS grid</returns>
public NorthEast Wgs84ToIcs(LatLon latLon)
{
// 1. Molodensky WGS84 -> Clark_1880_modified
var latLon80 = Molodensky(ToRadians(latLon), WGS84, CLARK80M);
// 2. Lat/Lon (Clark_1880_modified) -> Local Grid (ICS)
return LatLon2Grid(latLon80, CLARK80M, ICS);
}
