1 #ifndef _SG_GEODESY_HXX
2 #define _SG_GEODESY_HXX
4 #include <simgear/math/point3d.hxx>
7 * Convert from geocentric coordinates to geodetic coordinates
8 * @param lat_geoc (in) Geocentric latitude, radians, + = North
9 * @param radius (in) C.G. radius to earth center (meters)
10 * @param lat_geod (out) Geodetic latitude, radians, + = North
11 * @param alt (out) C.G. altitude above mean sea level (meters)
12 * @param sea_level_r (out) radius from earth center to sea level at
13 * local vertical (surface normal) of C.G. (meters)
15 void sgGeocToGeod(double lat_geoc, double radius,
16 double *lat_geod, double *alt, double *sea_level_r);
20 * Convert from geodetic coordinates to geocentric coordinates.
21 * WARNING: this function is non-reversible. Due to the fact that
22 * "up" is a different direction for geocentric and geodetic frames,
23 * you can not simply add your "alt" parameter to the "sl_radius"
24 * result and get back (via sgGeodToGeoc()) to the coordinates you
25 * started with. The error under normal conditions will be of
26 * centimeter order; whether that is important or not is application
27 * dependent. Consider using sgGeodToCart() instead.
29 * @param lat_geod (in) Geodetic latitude, radians, + = North
30 * @param alt (in) C.G. altitude above mean sea level (meters)
31 * @param sl_radius (out) SEA LEVEL radius to earth center (meters)
32 * @param lat_geoc (out) Geocentric latitude, radians, + = North
34 void sgGeodToGeoc(double lat_geod, double alt,
35 double *sl_radius, double *lat_geoc );
38 * Convert a cartesian point to a geodetic lat/lon/altitude.
40 * @param xyz (in) Pointer to cartesian point.
41 * @param lat (out) Latitude, in radians
42 * @param lon (out) Longitude, in radians
43 * @param alt (out) Altitude, in meters above the WGS84 ellipsoid
45 void sgCartToGeod(const double* xyz, double* lat, double* lon, double* alt);
48 * Convert a cartesian point to a geodetic lat/lon/altitude.
49 * Alternate form using Point3D objects.
51 * @param cartesian point
52 * @return geodetic point
54 inline Point3D sgCartToGeod(const Point3D& p)
56 double lat, lon, alt, xyz[3];
57 xyz[0] = p.x(); xyz[1] = p.y(); xyz[2] = p.z();
58 sgCartToGeod(xyz, &lat, &lon, &alt);
59 return Point3D(lon, lat, alt);
64 * Convert a geodetic lat/lon/altitude to a cartesian point.
66 * @param lat (in) Latitude, in radians
67 * @param lon (in) Longitude, in radians
68 * @param alt (in) Altitude, in meters above the WGS84 ellipsoid
69 * @param xyz (out) Pointer to cartesian point.
71 void sgGeodToCart(double lat, double lon, double alt, double* xyz);
74 * Convert a geodetic lat/lon/altitude to a cartesian point.
75 * Alternate form using Point3D objects.
77 * @param geodetic point
78 * @return cartesian point
80 inline Point3D sgGeodToCart(const Point3D& geod)
83 sgGeodToCart(geod.lat(), geod.lon(), geod.elev(), xyz);
84 return Point3D(xyz[0], xyz[1], xyz[2]);
88 * Given a starting position and an offset radial and distance,
89 * calculate an ending positon on a wgs84 ellipsoid.
90 * @param alt (in) meters
91 * @param lat1 (in) degrees
92 * @param lon1 (in) degrees
93 * @param az1 (in) degrees
94 * @param s (in) distance in meters
95 * @param lat2 (out) degrees
96 * @param lon2 (out) degrees
97 * @param az2 (out) return course in degrees
99 int geo_direct_wgs_84 ( double alt, double lat1,
100 double lon1, double az1,
101 double s, double *lat2, double *lon2,
106 * Given an altitude and two sets of (lat, lon) calculate great circle
107 * distance between them as well as the starting and ending azimuths.
108 * @param alt (in) meters
109 * @param lat1 (in) degrees
110 * @param lon1 (in) degrees
111 * @param lat2 (in) degrees
112 * @param lon2 (in) degrees
113 * @param az1 (out) start heading degrees
114 * @param az2 (out) end heading degrees
115 * @param s (out) distance meters
117 int geo_inverse_wgs_84( double alt, double lat1,
118 double lon1, double lat2,
119 double lon2, double *az1, double *az2,
122 #endif // _SG_GEODESY_HXX