// ///////////////////////////////////////////////////////////////////
// Calculate the ECI coordinates of the location "geo" at time "date".
// Assumes geo coordinates are km-based.
// Assumes the earth is an oblate spheroid as defined in WGS '72.
// Reference: The 1992 Astronomical Almanac, page K11
// Reference: www.celestrak.com (Dr. TS Kelso)
public Eci(CoordGeo geo, Julian date)
{
m_VecUnits = VecUnits.UNITS_KM;
double mfactor = Globals.TWOPI * (Globals.OMEGA_E / Globals.SEC_PER_DAY);
double lat = geo.m_Lat;
double lon = geo.m_Lon;
double alt = geo.Altitude.Kilometers;
// Calculate Local Mean Sidereal Time (theta)
double theta = date.toLMST(lon);
double c = 1.0 / Math.Sqrt(1.0 + Globals.F * (Globals.F - 2.0) * Globals.Sqr(Math.Sin(lat)));
double s = Globals.Sqr(1.0 - Globals.F) * c;
double achcp = (Globals.XKMPER * c + alt) * Math.Cos(lat);
m_date = date;
m_pos = new Vector();
m_pos.X = achcp * Math.Cos(theta); // km
m_pos.Y = achcp * Math.Sin(theta); // km
m_pos.Z = (Globals.XKMPER * s + alt) * Math.Sin(lat); // km
m_pos.W = Math.Sqrt(Globals.Sqr(m_pos.X) +
Globals.Sqr(m_pos.Y) +
Globals.Sqr(m_pos.Z)); // range, km
m_vel = new Vector();
m_vel.X = -mfactor * m_pos.Y; // km / sec
m_vel.Y = mfactor * m_pos.X;
m_vel.Z = 0.0;
m_vel.W = Math.Sqrt(Globals.Sqr(m_vel.X) + // range rate km/sec^2
Globals.Sqr(m_vel.Y));
}
// ///////////////////////////////////////////////////////////////////////////
// c'tor accepting:
// Latitude in degress (negative south)
// Longitude in degress (negative west)
// Altitude in km
public Site(double degLat, double degLon, double kmAlt)
{
m_geo =
new CoordGeo(Globals.Deg2Rad(degLat), Globals.Deg2Rad(degLon), kmAlt);
}
private CoordGeo m_geo; // lat, lon, alt of earth site
#region Construction
// //////////////////////////////////////////////////////////////////////////
public Site(CoordGeo geo)
{
m_geo = geo;
}
// ///////////////////////////////////////////////////////////////////
// Calculate the ECI coordinates of the location "geo" at time "date".
// Assumes geo coordinates are km-based.
// Assumes the earth is an oblate spheroid as defined in WGS '72.
// Reference: The 1992 Astronomical Almanac, page K11
// Reference: www.celestrak.com (Dr. TS Kelso)
public Eci(CoordGeo geo, Julian date)
{
m_VectorUnits = VectorUnits.Km;
double mfactor = Globals.TWOPI * (Globals.OMEGA_E / Globals.SEC_PER_DAY);
double lat = geo.Latitude;
double lon = geo.Longitude;
double alt = geo.Altitude;
// Calculate Local Mean Sidereal Time (theta)
double theta = date.toLMST(lon);
double c = 1.0 / Math.Sqrt(1.0 + Globals.F * (Globals.F - 2.0) * Globals.Sqr(Math.Sin(lat)));
double s = Globals.Sqr(1.0 - Globals.F) * c;
double achcp = (Globals.XKMPER * c + alt) * Math.Cos(lat);
m_Date = date;
m_Position = new Vector();
m_Position.X = achcp * Math.Cos(theta); // km
m_Position.Y = achcp * Math.Sin(theta); // km
m_Position.Z = (Globals.XKMPER * s + alt) * Math.Sin(lat); // km
m_Position.W = Math.Sqrt(Globals.Sqr(m_Position.X) +
Globals.Sqr(m_Position.Y) +
Globals.Sqr(m_Position.Z)); // range, km
m_Velocity = new Vector();
m_Velocity.X = -mfactor * m_Position.Y; // km / sec
m_Velocity.Y = mfactor * m_Position.X;
m_Velocity.Z = 0.0;
m_Velocity.W = Math.Sqrt(Globals.Sqr(m_Velocity.X) + // range rate km/sec^2
Globals.Sqr(m_Velocity.Y));
}
public static Distance GreatCircleDistance(CoordGeo pt1, CoordGeo pt2)
{
double distance = Math.Acos((Math.Sin(pt1.LatRad) * Math.Sin(pt2.LatRad)) + (Math.Cos(pt1.LatRad) * Math.Cos(pt2.LatRad) * Math.Cos(pt2.LonRad - pt1.LonRad)));
distance = distance * 3963.0; // Statute Miles
distance = distance * 1.609344; // to Km
Distance d = new Distance(distance, DistanceUnits.KILOMETERS);
return d;
}
private void MakeFootprint(DateTime atTime)
{
this._footPrint.Clear();
// Constants
double Re = 6378.137;
double TWOPI = Math.PI * 2.0;
double Rs = Math.Sqrt((Math.Pow(this.GetPositionECI(0).getPos().X, 2.0) + Math.Pow(this.GetPositionECI(0).getPos().Y, 2.0) + Math.Pow(this.GetPositionECI(0).getPos().Z, 2.0)));
double srad = Math.Acos(Re / Rs);
double latTemp = this.GetPositionGeo(atTime).m_Lat;
double lonTemp = this.GetPositionGeo(atTime).m_Lon;
double cla = Math.Cos(latTemp);
double sla = Math.Sin(latTemp);
double clo = Math.Cos(lonTemp);
double slo = Math.Sin(lonTemp);
double sra = Math.Sin(srad);
double cra = Math.Cos(srad);
double angle = 0.0;
double X, Y, Z, x, y, z, lat, lon, lon1, lon2;
for (int i = 0; i < 73; i++)
{
angle = i * (TWOPI / 72.0);
X = cra;
Y = sra * Math.Sin(angle);
Z = sra * Math.Cos(angle);
x = (X * cla) - (Z * sla);
y = Y;
z = (X * sla) + (Z * cla);
X = (x * clo) - (y * slo);
Y = (x * slo) + (y * clo);
Z = z;
lon = Math.Atan2(Y, X);
lon1 = this.FN_Atan(Y, X);
lon2 = this.FN_Atan2(Y, X);
lat = Math.Asin(Z);
CoordGeo cg = new CoordGeo(lat, lon, 0);
this._footPrint.Add(cg);
if (i == 0)
{
this._footDiam = new Distance(Globals.GreatCircleDistance(this.Position, cg).Kilometers * 2.0, DistanceUnits.KILOMETERS);
}
}
}
public static CoordGeo CalculatePointOnRhumbLine(CoordGeo point, double azimuth, double dist)
{
double lat1 = point.LatRad;// (double)com.bbn.openmap.geo.Geo.radians(point.getLatitude());
double lon1 = point.LonRad;// (double)com.bbn.openmap.geo.Geo.radians(point.getLongitude());
double d = dist / 1855.3 * Math.PI / 10800.0;
double lat = 0.0;
double lon = 0.0;
lat = lat1 + d * Math.Cos(azimuth);
double dphi = Math.Log((1 + Math.Sin(lat)) / Math.Cos(lat)) - Math.Log((1 + Math.Sin(lat1)) / Math.Cos(lat1));
double dlon = 0.0;
if (Math.Abs(Math.Cos(azimuth)) > Math.Sqrt(0.00000000000001))
{
dlon = dphi * Math.Tan(azimuth);
}
else
{ // along parallel
dlon = Math.Sin(azimuth) * d / Math.Cos(lat1);
}
lon = Mod(lon1 - dlon + Math.PI, 2 * Math.PI) - Math.PI;
//System.out.println("calculatePointOnRhumbLine: lat1 = "+lat1+"+ lon1 = "+lon1 + " lat = "+lat+"+ lon = "+lon);
return new CoordGeo(lat, lon, 0);// LatLonPoint((float)lat, (float)lon, true);
}
