/*
* Calculate new position given starting point with bearing and distance traveled in meters
*
* return WGS84Point
*/
public static WGS84Point DestinationPoint(WGS84Point point, double bearing, double distanceTraveledInMeters)
{
GeoVector n1 = new GeoVector();
double angle;
double earthRadiusInMeters = _earthRadiusInKM * 1000.0;
double b;
GeoVector northPole = new GeoVector(0, 0, 1);
GeoVector de = new GeoVector(); // direction east
GeoVector dn = new GeoVector(); // direction north
GeoVector deSin = new GeoVector();
GeoVector dnCos = new GeoVector();
GeoVector d = new GeoVector(); // direction vector at n1 (C x n1 where C = great circle)
GeoVector x = new GeoVector(); // component of n2 parallel to n1
GeoVector y = new GeoVector(); // component of n2 perpendicular to n1
GeoVector n2 = new GeoVector();
n1 = WGS84PointToNVector(point);
angle = distanceTraveledInMeters / earthRadiusInMeters; // angle in radians
b = bearing * Math.PI / 180.0; // bearing in radians
de = Cross(northPole, n1);
de = Unit(de);
dn = Cross(n1, de);
deSin = Times(de, Math.Sin(b));
dnCos = Times(dn, Math.Cos(b));
d = Plus(dnCos, deSin);
x = Times(n1, Math.Cos(angle));
y = Times(d, Math.Sin(angle));
n2 = Plus(x, y);
// you have got to be kidding me
return(NVectorToWGS84Point(n2));
}
/*
* Calculate point of intersection of two paths.
*
* If c1 and c2 are great circles through start and end points then candidate intersections are c1 × c2 and c2 × c1.
* Choose closer intersection.
*
* return WGS84Point
*/
public static WGS84Point Intersection(WGS84Point path1P1, double path1Bearing, WGS84Point path2P1, double path2Bearing)
{
GeoVector p1v1 = WGS84PointToNVector(path1P1);
GeoVector p2v1 = WGS84PointToNVector(path2P1);
GeoVector c1 = new GeoVector(); //great circle through path1P1 and path1P2 surface normal
GeoVector c2 = new GeoVector(); //great circle through path2P1 and path2P2 surface normal
GeoVector i1 = new GeoVector(); // intersection 1
GeoVector i2 = new GeoVector(); // intersection 2
double sum1, sum2;
// calculate great circle surface normals
c1 = GreatCircle(p1v1, path1Bearing);
c2 = GreatCircle(p2v1, path2Bearing);
// get both intersections
i1 = Cross(c1, c2);
i2 = Cross(c2, c1);
//calculate sum of distances from all points to each intersection, choose closest
sum1 = DistanceInMeters(p1v1, i1) + DistanceInMeters(p2v1, i1);
sum2 = DistanceInMeters(p1v1, i2) + DistanceInMeters(p2v1, i2);
if (sum1 < sum2)
{
return(NVectorToWGS84Point(i1));
}
return(NVectorToWGS84Point(i2));
}
/*
* Calculate distance between two WGS84Point in meters
*
* return meters as double
*/
public static double DistanceInMeters(WGS84Point point1, WGS84Point point2)
{
GeoVector vec1 = WGS84PointToNVector(point1);
GeoVector vec2 = WGS84PointToNVector(point2);
return(DistanceInMeters(vec1, vec2));
}
/*
* Convert NVector to WGS84Point (lat/long)
*
* return WGS84Point
*/
public static WGS84Point NVectorToWGS84Point(GeoVector vec)
{
WGS84Point point = new WGS84Point();
point.Latitude = Math.Atan2(vec._z, Math.Sqrt((vec._x * vec._x) + (vec._y * vec._y))) * 180.0 / Math.PI;
point.Longitude = Math.Atan2(vec._y, vec._x) * 180.0 / Math.PI;
return(point);
}
/*
* Calculate the midpoint between two GPS coordinate points
*
* return WGS84Point
*/
public static WGS84Point MidpointBetween(WGS84Point point1, WGS84Point point2)
{
GeoVector vec = new GeoVector();
GeoVector vec1 = WGS84PointToNVector(point1);
GeoVector vec2 = WGS84PointToNVector(point2);
vec = Plus(vec1, vec2);
vec = Unit(vec);
return(NVectorToWGS84Point(vec));
}
/*
* Convert WGS84Point (lat/long) to NVector
*
* return GeoVector
*/
public static GeoVector WGS84PointToNVector(WGS84Point point)
{
GeoVector vec = new GeoVector();
double lat;
double lon;
//convert lat/lon to radians
lat = point.Latitude * Math.PI / 180.0;
lon = point.Longitude * Math.PI / 180.0;
//create right handed vector x -> 0°E,0°N; y -> 90°E,0°N, z -> 90°N
vec._x = Math.Cos(lat) * Math.Cos(lon);
vec._y = Math.Cos(lat) * Math.Sin(lon);
vec._z = Math.Sin(lat);
return(vec);
}
/*
* Calculate cross track distance, the distance in meters from a point to the great circle defined
* by a path start point and bearing, distance is signed (negative to left of path, positive to right of path)
*
* return meters as double
*/
public static double CrossTrackDistanceInMeters(WGS84Point point, WGS84Point pathP1, double pathBearing)
{
GeoVector vec1 = WGS84PointToNVector(point);
GeoVector pv1 = WGS84PointToNVector(pathP1);
GeoVector c1 = new GeoVector(); //great circle from pathP1 using bearing
double angle;
// calculate great circle surface normal
c1 = GreatCircle(pv1, pathBearing);
// calculate angle between surface and point
angle = AngleBetweenInRadians(c1, vec1, new GeoVector()) - (Math.PI / 2);
//return distance in meters
return(angle * _earthRadiusInKM * 1000.0);
}
/*
* Calculate cross track distance, the distance in meters from a point to the great circle defined
* by a path start point and end point, distance is signed (negative to left of path, positive to right of path)
*
* return meters as double
*/
public static double CrossTrackDistanceInMeters(WGS84Point point, WGS84Point pathP1, WGS84Point pathP2)
{
GeoVector vec1 = WGS84PointToNVector(point);
GeoVector pv1 = WGS84PointToNVector(pathP1);
GeoVector pv2 = WGS84PointToNVector(pathP2);
GeoVector c1 = new GeoVector(); //great circle through pathP1 and pathP2 surface normal
double angle;
// calculate great circle surface normal
c1 = Cross(pv1, pv2);
// calculate angle between surface and point
angle = AngleBetweenInRadians(c1, vec1, new GeoVector()) - (Math.PI / 2);
//return distance in meters
return(angle * _earthRadiusInKM * 1000.0);
}
/*
* Calculate the signed angle from path1 to path2 (-180 to 180)
* Path1 is defined by its GPS start point and bearing, path2 is a GPS coordinate pair
*
* return degrees from north (-180 to 180) as double
*/
public static double AngleBetweenPathsInDegrees(WGS84Point path1P1, double path1Bearing, WGS84Point path2P1, WGS84Point path2P2)
{
GeoVector p1v1 = WGS84PointToNVector(path1P1);
GeoVector p2v1 = WGS84PointToNVector(path2P1);
GeoVector p2v2 = WGS84PointToNVector(path2P2);
GeoVector c1 = new GeoVector(); //great circle through path1P1 and path1Bearing
GeoVector c2 = new GeoVector(); //great circle through path2P1 and path2P2 surface normal
double angle;
// calculate great circle surface normals
c1 = GreatCircle(p1v1, path1Bearing);
c2 = Cross(p2v1, p2v2);
// calculate angle between surface normals using vector to first point as sign vector
angle = AngleBetweenInRadians(c2, c1, p1v1) * 180.0 / Math.PI;
//cout << "GC1(B): " << c1._x << "," << c1._y << "," << c1._z << " B: " << path1Bearing << "\n";
return(angle);
}
/*
* Calculate great circle given a point and a bearing (degrees 0 to 360)
*
* return GeoVector
*/
public static GeoVector GreatCircle(GeoVector vec, double bearing)
{
GeoVector gc = new GeoVector();
double lat;
double lon;
double bear;
WGS84Point point = new WGS84Point();
point = NVectorToWGS84Point(vec);
//cout << "Point: " << point.Latitude << "," << point.Longitude << "\n";
//convert to radians
lat = point.Latitude * Math.PI / 180.0;
lon = point.Longitude * Math.PI / 180.0;
bear = bearing * Math.PI / 180.0;
gc._x = (Math.Sin(lon) * Math.Cos(bear)) - (Math.Sin(lat) * Math.Cos(lon) * Math.Sin(bear));
gc._y = (Math.Cos(lon) * -1.0 * Math.Cos(bear)) - (Math.Sin(lat) * Math.Sin(lon) * Math.Sin(bear));
gc._z = Math.Cos(lat) * Math.Sin(bear);
return(gc);
}
/*
* Calculate initial bearing from point1 to point2 in degrees from north (0 to 360)
*
* return degrees from north (0 to 360) as double
*/
public static double BearingInDegrees(WGS84Point point1, WGS84Point point2)
{
GeoVector vec1 = WGS84PointToNVector(point1);
GeoVector vec2 = WGS84PointToNVector(point2);
GeoVector northPole = new GeoVector(0, 0, 1);
GeoVector c1 = new GeoVector(); //great circle through point1 and point2 surface normal
GeoVector c2 = new GeoVector(); //great circle through point1 and north pole surface normal
double bearing;
// calculate great circle surface normals
c1 = Cross(vec1, vec2);
c2 = Cross(vec1, northPole);
//signed bearing in degrees (-180 to 180)
bearing = AngleBetweenInRadians(c1, c2, vec1) * 180.0 / Math.PI;
//return normalized bearing (0 to 360)
if (bearing < 0.0)
{
bearing += 360.0;
}
return(bearing);
}