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 CoordGeo(double lat, double lon, double alt)
{
m_Lat = lat;
m_Lon = lon;
m_Alt = new Distance(alt, DistanceUnits.KILOMETERS);
}
private bool InitFromTime(DateTime utc)
{
utc = Globals.InsureUTC(utc);
TimeSpan ts = utc - this.EpochUTC;
double minutes = ts.TotalMinutes;
Eci position = new Eci();
try
{
position = this._orbit.getPosition(minutes);
}
catch (Exception)
{
return false;
}
this._lat = new Angle(position.toGeo().LatDeg, AngleUnits.DEGREES);
this._lon = new Angle(position.toGeo().LonDeg, AngleUnits.DEGREES);
this._alt = position.toGeo().Altitude;
Vector velVec = position.getVel();
this._velX = velVec.X;
this._velY = velVec.Y;
this._velZ = velVec.Z;
this._vel = Math.Sqrt(Math.Pow(this._velX, 2.0) + Math.Pow(this._velY, 2.0) + Math.Pow(this._velZ, 2.0));
CoordTopo ct = this.Site.getLookAngle(position);
this._az = new Angle(ct.Azimuth);
this._el = new Angle(ct.Elevation);
this._rg = new Distance(ct.Range, DistanceUnits.KILOMETERS);
this._rr = ct.RangeRate;
this.MakeFootprint(utc);
return true;
}
public double m_Lon; // Longitude, radians (negative west)
#endregion Fields
#region Constructors
public CoordGeo()
{
m_Lat = 0.0;
m_Lon = 0.0;
m_Alt = new Distance(0.0);
}