/// <summary>
///
/// </summary>
/// <param name="point1"></param>
/// <param name="point2"></param>
/// <returns></returns>
public static double AngularDistance(IKmlPoint point1, IKmlPoint point2)
{
double phi1 = point1.getLatitude().DegreesToRadians();
double phi2 = point2.getLatitude().DegreesToRadians();
double d_phi = (point2.getLatitude() - point1.getLatitude()).DegreesToRadians();
double d_lmd = (point2.getLongitude() - point1.getLongitude()).DegreesToRadians();
double A = Math.Pow(Math.Sin(d_phi / 2), 2) +
Math.Cos(phi1) * Math.Cos(phi2) *
Math.Pow(Math.Sin(d_lmd / 2), 2);
return 2 * Math.Atan2(Math.Sqrt(A), Math.Sqrt(1 - A));
}
/// <summary>
/// Draws the line string.
/// </summary>
/// <param name="ge">The ge.</param>
/// <param name="p1">The p1.</param>
/// <param name="p2">The p2.</param>
/// <returns></returns>
public static IKmlPlacemark DrawLineString(IGEPlugin ge, IKmlPoint p1, IKmlPoint p2)
{
IKmlPlacemark lineStringPlacemark = ge.createPlacemark(String.Empty);
IKmlLineString lineString = ge.createLineString(String.Empty);
lineStringPlacemark.setGeometry(lineString);
lineString.setTessellate(1);
lineString.getCoordinates().pushLatLngAlt(p1.getLatitude(), p1.getLongitude(), 0);
lineString.getCoordinates().pushLatLngAlt(p2.getLatitude(), p2.getLongitude(), 0);
return lineStringPlacemark;
}
/// <summary>
///
/// </summary>
/// <param name="origin">The first point</param>
/// <param name="heading"></param>
/// <param name="distance"></param>
/// <returns></returns>
public static IKmlPoint Destination(IKmlPoint origin, double heading, double distance)
{
double phi1 = origin.getLatitude().DegreesToRadians();
double lmd1 = origin.getLongitude().DegreesToRadians();
double sin_phi1 = Math.Sin(phi1);
double angularDistance = distance / EARTH_RADIUS;
double heading_rad = heading.DegreesToRadians();
double sin_angularDistance = Math.Sin(angularDistance);
double cos_angularDistance = Math.Cos(angularDistance);
double phi2 =
Math.Asin(sin_phi1 * cos_angularDistance + Math.Cos(phi1) *
sin_angularDistance * Math.Cos(heading_rad));
IKmlPoint result = origin;
result.set(0, 0, 0, 0, 0, 0);
result.setLatLng(phi2.RadiansToDegrees(),
Math.Atan2(Math.Sin(heading_rad) * sin_angularDistance * Math.Cos(phi2),
cos_angularDistance - sin_phi1 * Math.Sin(phi2)).RadiansToDegrees() + origin.getLongitude());
return result;
}
/// <summary>
/// Calculates an intermediate point on the geodesic between the two given points
/// See: http://williams.best.vwh.net/avform.htm#Intermediate
/// </summary>
/// <param name="origin">The first point</param>
/// <param name="destination">The second point</param>
/// <param name="fraction">Intermediate location as a decimal fraction (T value)</param>
/// <returns></returns>
public static IKmlPoint IntermediatePoint(IKmlPoint origin, IKmlPoint destination, double fraction)
{
if (fraction > 1 || fraction < 0)
{
throw new ArgumentOutOfRangeException("fraction must be between 0 and 1");
}
// TODO: check for antipodality and fail w/ exception in that case
double phi1 = origin.getLatitude().DegreesToRadians();
double phi2 = destination.getLatitude().DegreesToRadians();
double lmd1 = origin.getLongitude().DegreesToRadians();
double lmd2 = destination.getLongitude().DegreesToRadians();
double cos_phi1 = Math.Cos(phi1);
double cos_phi2 = Math.Cos(phi2);
double angularDistance = AngularDistance(origin, destination);
double sin_angularDistance = Math.Sin(angularDistance);
double A = Math.Sin((1 - fraction) * angularDistance) / sin_angularDistance;
double B = Math.Sin(fraction * angularDistance) / sin_angularDistance;
double x = A * cos_phi1 * Math.Cos(lmd1) + B * cos_phi2 * Math.Cos(lmd2);
double y = A * cos_phi1 * Math.Sin(lmd1) + B * cos_phi2 * Math.Sin(lmd2);
double z = A * Math.Sin(phi1) + B * Math.Sin(phi2);
IKmlPoint result = origin;
result.set(0, 0, 0, 0, 0, 0);
result.setLatLng(Math.Atan2(z, Math.Sqrt(Math.Pow(x, 2) + Math.Pow(y, 2))).RadiansToDegrees(),
Math.Atan2(y, x).RadiansToDegrees());
return result;
}
/// <summary>
///
/// </summary>
/// <param name="origin"></param>
/// <param name="destination"></param>
/// <returns></returns>
public static double Heading(IKmlPoint origin, IKmlPoint destination)
{
double phi1 = origin.getLatitude().DegreesToRadians();
double phi2 = destination.getLatitude().DegreesToRadians();
double cos_phi2 = Math.Cos(phi2);
double d_lmd = (destination.getLongitude() - origin.getLongitude()).DegreesToRadians();
return NormaliseAngle(
Math.Atan2(Math.Sin(d_lmd) * cos_phi2,
Math.Cos(phi1) * Math.Sin(phi2) - Math.Sin(phi1) *
cos_phi2 * Math.Cos(d_lmd))).RadiansToDegrees();
}
/// <summary>
/// This function is based on the geodesy-library code by Mike Gavaghan
/// See http://www.gavaghan.org/blog/2007/08/06/c-gps-receivers-and-geocaching-vincentys-formula/
/// </summary>
/// <param name="origin">The first point</param>
/// <param name="destination">The second point</param>
/// <returns>The distance between the given points in metres</returns>
public static double DistanceVincenty(IKmlPoint origin, IKmlPoint destination)
{
//
// All equation numbers refer back to Vincenty's publication:
// See http://www.ngs.noaa.gov/PUBS_LIB/inverse.pdf
//
// WGS84 Ellipsoid
double a = 6378137;
double b = 6356752.3142;
double f = 1 / 298.257223563;
// get parameters as radians
double phi1 = origin.getLatitude().DegreesToRadians();
double phi2 = destination.getLatitude().DegreesToRadians();
double lambda1 = origin.getLongitude().DegreesToRadians();
double lambda2 = destination.getLongitude().DegreesToRadians();
// calculations
double a2 = a * a;
double b2 = b * b;
double a2b2b2 = (a2 - b2) / b2;
double omega = lambda2 - lambda1;
double tanphi1 = Math.Tan(phi1);
double tanU1 = (1.0 - f) * tanphi1;
double U1 = Math.Atan(tanU1);
double sinU1 = Math.Sin(U1);
double cosU1 = Math.Cos(U1);
double tanphi2 = Math.Tan(phi2);
double tanU2 = (1.0 - f) * tanphi2;
double U2 = Math.Atan(tanU2);
double sinU2 = Math.Sin(U2);
double cosU2 = Math.Cos(U2);
double sinU1sinU2 = sinU1 * sinU2;
double cosU1sinU2 = cosU1 * sinU2;
double sinU1cosU2 = sinU1 * cosU2;
double cosU1cosU2 = cosU1 * cosU2;
// eq. 13
double lambda = omega;
// intermediates we'll need to compute 's'
double A = 0.0;
double B = 0.0;
double sigma = 0.0;
double deltasigma = 0.0;
double lambda0;
for (int i = 0; i < 20; i++)
{
lambda0 = lambda;
double sinlambda = Math.Sin(lambda);
double coslambda = Math.Cos(lambda);
// eq. 14
double sin2sigma = (cosU2 * sinlambda * cosU2 * sinlambda) + Math.Pow(cosU1sinU2 - sinU1cosU2 * coslambda, 2.0);
double sinsigma = Math.Sqrt(sin2sigma);
// eq. 15
double cossigma = sinU1sinU2 + (cosU1cosU2 * coslambda);
// eq. 16
sigma = Math.Atan2(sinsigma, cossigma);
// eq. 17 Careful! sin2sigma might be almost 0!
double sinalpha = (sin2sigma == 0) ? 0.0 : cosU1cosU2 * sinlambda / sinsigma;
double alpha = Math.Asin(sinalpha);
double cosalpha = Math.Cos(alpha);
double cos2alpha = cosalpha * cosalpha;
// eq. 18 Careful! cos2alpha might be almost 0!
double cos2sigmam = cos2alpha == 0.0 ? 0.0 : cossigma - 2 * sinU1sinU2 / cos2alpha;
double u2 = cos2alpha * a2b2b2;
double cos2sigmam2 = cos2sigmam * cos2sigmam;
// eq. 3
A = 1.0 + u2 / 16384 * (4096 + u2 * (-768 + u2 * (320 - 175 * u2)));
// eq. 4
B = u2 / 1024 * (256 + u2 * (-128 + u2 * (74 - 47 * u2)));
// eq. 6
deltasigma = B * sinsigma * (cos2sigmam + B / 4 * (cossigma * (-1 + 2 * cos2sigmam2) - B / 6 * cos2sigmam * (-3 + 4 * sin2sigma) * (-3 + 4 * cos2sigmam2)));
// eq. 10
double C = f / 16 * cos2alpha * (4 + f * (4 - 3 * cos2alpha));
// eq. 11 (modified)
lambda = omega + (1 - C) * f * sinalpha * (sigma + C * sinsigma * (cos2sigmam + C * cossigma * (-1 + 2 * cos2sigmam2)));
// see how much improvement we got
double change = Math.Abs((lambda - lambda0) / lambda);
if ((i > 1) && (change < EPSILON))
{
break;
}
}
// eq. 19
double s = b * A * (sigma - deltasigma);
return s;
}
/// <summary>
/// Look at the given point
/// </summary>
/// <param name="ge">the plugin</param>
/// <param name="point">the point to look at</param>
public static void LookAt(IGEPlugin ge, IKmlPoint point)
{
LookAt(ge, point.getLatitude(), point.getLongitude());
}
/*This is called by the Javascript function that will show the ruler point on the map and will do the calculation of distance */
public void createRulerPoint(IKmlPlacemark rulerPoint, IKmlPoint point)
{
IKmlIcon rulerPointIcon = ge.createIcon("");
rulerPointIcon.setHref("http://maps.google.com/mapfiles/kml/shapes/placemark_square.png");
IKmlStyle rulerPointStyle = ge.createStyle("");
rulerPointStyle.getIconStyle().setIcon(rulerPointIcon);
rulerPoint.setStyleSelector(rulerPointStyle);
ruler.getFeatures().appendChild(rulerPoint); // Add the point to the map.
/*We will then implement the feature that will calculate the distance between the points*/
linePoints.getCoordinates().pushLatLngAlt(point.getLatitude(), point.getLongitude(), 0);
line.setGeometry(linePoints);
if (pointsMeasured != 0)
{
//This means this is not the first point we're measuring. Hence we should find out the distance
//The distance will be the distance measured so far, plus the distance between the last point and the current point
rulerDistance += Math.Round(DistanceAlgorithm.DistanceBetweenPlaces(lastPoint.getLatitude(), lastPoint.getLongitude(), point.getLatitude(), point.getLongitude()), 2);
rulerDistanceText.Text = rulerDistance.ToString() + " km";
++pointsMeasured;
}
else
{
++pointsMeasured;
}
lastPoint = point;
}
