185 lines
5.5 KiB
C++
185 lines
5.5 KiB
C++
/**
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* \file sg_geodesy.hxx
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* Routines to convert between geodetic and geocentric coordinate systems.
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* Copied and adapted directly from LaRCsim/ls_geodesy.c
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*/
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// See below for the complete original LaRCsim comments.
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//
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// $Id$
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#ifndef _SG_GEODESY_HXX
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#define _SG_GEODESY_HXX
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#ifndef __cplusplus
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# error This library requires C++
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#endif
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#include <simgear/math/point3d.hxx>
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#include <simgear/math/polar3d.hxx>
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/**
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* Convert from geocentric coordinates to geodetic coordinates
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* @param lat_geoc (in) Geocentric latitude, radians, + = North
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* @param radius (in) C.G. radius to earth center (meters)
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* @param lat_geod (out) Geodetic latitude, radians, + = North
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* @param alt (out) C.G. altitude above mean sea level (meters)
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* @param sea_level_r (out) radius from earth center to sea level at
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* local vertical (surface normal) of C.G. (meters)
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*/
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void sgGeocToGeod( double lat_geoc, double radius, double
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*lat_geod, double *alt, double *sea_level_r );
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/**
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* Convert from geodetic coordinates to geocentric coordinates
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* @param lat_geod (in) Geodetic latitude, radians, + = North
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* @param alt (in) C.G. altitude above mean sea level (meters)
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* @param sl_radius (out) SEA LEVEL radius to earth center (meters)
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* (add Altitude to get true distance from earth center.
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* @param lat_geoc (out) Geocentric latitude, radians, + = North
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*/
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void sgGeodToGeoc( double lat_geod, double alt, double *sl_radius,
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double *lat_geoc );
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/**
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* Convert a geodetic point lon(radians), lat(radians), elev(meter) to
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* a cartesian point.
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* @param geodetic point
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* @return cartesian point
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*/
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inline Point3D sgGeodToCart(const Point3D& geod) {
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double gc_lon, gc_lat, sl_radius;
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// printf("A geodetic point is (%.2f, %.2f, %.2f)\n",
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// geod[0], geod[1], geod[2]);
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gc_lon = geod.lon();
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sgGeodToGeoc(geod.lat(), geod.radius(), &sl_radius, &gc_lat);
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// printf("A geocentric point is (%.2f, %.2f, %.2f)\n", gc_lon,
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// gc_lat, sl_radius+geod[2]);
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Point3D pp = Point3D( gc_lon, gc_lat, sl_radius + geod.radius());
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return sgPolarToCart3d(pp);
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}
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/**
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* Given a starting position and an offset radial and distance,
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* calculate an ending positon on a wgs84 ellipsoid.
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* @param alt (in) meters
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* @param lat1 (in) degrees
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* @param lon1 (in) degrees
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* @param az1 (in) degrees
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* @param s (in) distance in meters
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* @param lat2 (out) degrees
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* @param lon2 (out) degrees
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* @param az2 (out) return course in degrees
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*/
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int geo_direct_wgs_84 ( double alt, double lat1, double lon1, double az1,
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double s, double *lat2, double *lon2, double *az2 );
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// given alt, lat1, lon1, lat2, lon2, calculate starting and ending
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// az1, az2 and distance (s). Lat, lon, and azimuth are in degrees.
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// distance in meters
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int geo_inverse_wgs_84( double alt, double lat1, double lon1, double lat2,
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double lon2, double *az1, double *az2, double *s );
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/***************************************************************************
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TITLE: ls_geodesy
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----------------------------------------------------------------------------
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FUNCTION: Converts geocentric coordinates to geodetic positions
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----------------------------------------------------------------------------
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MODULE STATUS: developmental
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----------------------------------------------------------------------------
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GENEALOGY: Written as part of LaRCSim project by E. B. Jackson
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----------------------------------------------------------------------------
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DESIGNED BY: E. B. Jackson
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CODED BY: E. B. Jackson
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MAINTAINED BY: E. B. Jackson
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----------------------------------------------------------------------------
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MODIFICATION HISTORY:
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DATE PURPOSE BY
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930208 Modified to avoid singularity near polar region. EBJ
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930602 Moved backwards calcs here from ls_step. EBJ
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931214 Changed erroneous Latitude and Altitude variables to
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*lat_geod and *alt in routine ls_geoc_to_geod. EBJ
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940111 Changed header files from old ls_eom.h style to ls_types,
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and ls_constants. Also replaced old DATA type with new
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SCALAR type. EBJ
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CURRENT RCS HEADER:
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$Header$
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* Revision 1.5 1994/01/11 18:47:05 bjax
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* Changed include files to use types and constants, not ls_eom.h
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* Also changed DATA type to SCALAR type.
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*
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* Revision 1.4 1993/12/14 21:06:47 bjax
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* Removed global variable references Altitude and Latitude. EBJ
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*
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* Revision 1.3 1993/06/02 15:03:40 bjax
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* Made new subroutine for calculating geodetic to geocentric; changed name
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* of forward conversion routine from ls_geodesy to ls_geoc_to_geod.
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*
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----------------------------------------------------------------------------
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REFERENCES:
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[ 1] Stevens, Brian L.; and Lewis, Frank L.: "Aircraft
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Control and Simulation", Wiley and Sons, 1992.
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ISBN 0-471-61397-5
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----------------------------------------------------------------------------
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CALLED BY: ls_aux
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----------------------------------------------------------------------------
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CALLS TO:
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----------------------------------------------------------------------------
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INPUTS:
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lat_geoc Geocentric latitude, radians, + = North
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radius C.G. radius to earth center, ft
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----------------------------------------------------------------------------
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OUTPUTS:
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lat_geod Geodetic latitude, radians, + = North
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alt C.G. altitude above mean sea level, ft
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sea_level_r radius from earth center to sea level at
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local vertical (surface normal) of C.G.
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--------------------------------------------------------------------------*/
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#endif // _SG_GEODESY_HXX
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