GM_ProjectPointToECEF

GM_DLL_EXPORTED GM_Error_t32 __stdcall GM_ProjectPointToECEF

(

double                  aXIn,       // IN: X coordinate of input point

double                  aYIn,       // IN: Y coordinate of input point

double                  aZIn,       // IN: Z coordinate of input point (meters above ellipsoid), usually 0

double*                 aX,         // OUT: ECEF X coordinate of input

double*                 aY,         // OUT: ECEF Y coordinate of input

double*                 aZ,         // OUT: ECEF Z coordinate of input

DATUM                   aDatum,     // IN: datum for ECEF conversion (normally GM_DATUM_WGS_84)

const GM_Projection_t*  aProjIn     // IN: projection of input point (NULL for current projection)

)

// Convert a sample lat/lon point to ECEF

GM_Projection_t theGeoProj;

::memset( &theGeoProj, 0, sizeof theGeoProj );

theGeoProj.mProjSys = GM_PRJ_GEO;

theGeoProj.mDatum = GM_DATUM_WGS_84;

theGeoProj.mUnit = GM_PRJ_UNIT_ARC_DEGREES;

double theLat = 39.0;

double theLon = -90.0;

double theX, theY, theZ;

GM_Error_t32 theErr = GM_ProjectPointToECEF( theLon, theLat, &theX, &theY, &theZ, GM_DATUM_WGS_84, &theGeoProj );



// Convert back, yielding the same point as you started with

double theRevLat, theRevLon;

theErr = GM_ProjectPointFromECEF( theX, theY, theZ, &theRevLon, &theRevLat, GM_DATUM_WGS_84, &theGeoProj );