georec_c |

## Procedurevoid georec_c ( SpiceDouble lon, SpiceDouble lat, SpiceDouble alt, SpiceDouble re, SpiceDouble f, SpiceDouble rectan[3] ) ## AbstractConvert geodetic coordinates to rectangular coordinates. ## Required_ReadingNone. ## KeywordsCONVERSION, COORDINATES ## Brief_I/OVARIABLE I/O DESCRIPTION -------- --- -------------------------------------------------- lon I Geodetic longitude of point (radians). lat I Geodetic latitude of point (radians). alt I Altitude of point above the reference spheroid. re I Equatorial radius of the reference spheroid. f I Flattening coefficient. rectan O Rectangular coordinates of point. ## Detailed_Inputlon Geodetic longitude of the input point. This is the angle between the prime meridian and the meridian containing `rectan'. The direction of increasing longitude is from the +X axis towards the +Y axis. Longitude is measured in radians. On input, the range of longitude is unrestricted. lat Geodetic latitude of the input point. For a point P on the reference spheroid, this is the angle between the XY plane and the outward normal vector at P. For a point P not on the reference spheroid, the geodetic latitude is that of the closest point to P on the spheroid. Latitude is measured in radians. On input, the range of latitude is unrestricted. alt Altitude of point above the reference spheroid. `alt' must be in the same units as `re'. re Equatorial radius of a reference spheroid. This spheroid is a volume of revolution: its horizontal cross sections are circular. The shape of the spheroid is defined by an equatorial radius `re' and a polar radius `rp'. `re' must be in the same units as `alt'. f Flattening coefficient = (re-rp) / re, where `rp' is the polar radius of the spheroid. ## Detailed_Outputrectan Rectangular coordinates of the input point. The units associated with `rectan' are those associated with the inputs `alt' and `re'. ## ParametersNone. ## Exceptions1) If the equatorial radius is less than or equal to zero, the error SPICE(VALUEOUTOFRANGE) is signaled. 2) If the flattening coefficient is greater than or equal to one, the error SPICE(VALUEOUTOFRANGE) is signaled. ## FilesNone. ## ParticularsGiven the geodetic coordinates of a point, and the constants describing the reference spheroid, this routine returns the bodyfixed rectangular coordinates of the point. The bodyfixed rectangular frame is that having the x-axis pass through the 0 degree latitude 0 degree longitude point. The y-axis passes through the 0 degree latitude 90 degree longitude. The z-axis passes through the 90 degree latitude point. For some bodies this coordinate system may not be a right-handed coordinate system. ## ExamplesThis routine can be used to convert body fixed geodetic coordinates (such as the used for United States Geological Survey topographic maps) to bodyfixed rectangular coordinates such as the Satellite Tracking and Data Network of 1973. The code would look something like this /. Using the equatorial radius of the Clark66 spheroid (CLARKR = 6378.2064 km) and the Clark 66 flattening factor (CLARKF = 1.0 / 294.9787 ) convert to body fixed rectangular coordinates. ./ ## RestrictionsNone. ## Literature_ReferencesSee FUNDAMENTALS OF ASTRODYNAMICS, Bate, Mueller, White published by Dover for a description of geodetic coordinates. ## Author_and_InstitutionC.H. Acton (JPL) N.J. Bachman (JPL) H.A. Neilan (JPL) W.L. Taber (JPL) E.D. Wright (JPL) ## Version-CSPICE Version 1.0.3, 26-JUL-2016 (BVS) Minor headers edits. -CSPICE Version 1.0.2, 30-JUL-2003 (NJB) Various header corrections were made. -CSPICE Version 1.0.1, 11-JAN-2003 (EDW) Removed a spurious non-printing character. -CSPICE Version 1.0.0, 08-FEB-1998 (EDW) ## Index_Entriesgeodetic to rectangular coordinates |

Wed Apr 5 17:54:35 2017