The list of spheroids available is somewhat dynamic. At the time of this release, available spheroids included: airy, australian, bessel, clark66, everest, grs80, hayford, international, krasovsky, wgs66, wgs72, and wgs84 (see table below).
This command can be run either non-interactively or interactively. The user can run the program non-interactively by entering desired flag settings and parameter values on the command line using the following format:
Input can be entered from the keyboard or from an input file. In either case, input should be entered with one longitude and latitude pair per line, in either of the below forms:
Similarly, the user can elect to send output to an output file or (by default) to standard output (the user's terminal screen). If the user sets the -w flag, output will be printed in a format suitable for input to programs like d.points. Example input and output are shown below (see EXAMPLE).
Program flag settings and parameters have the following meanings.
Spheroid: |Semi-major axis| Eccentricity | Commonly | Equatorial | sqrd (e), | used for: | Radius (a): | Flattening (f) or| | | Polar Radius (b):| _____________|_______________|__________________|______________ airy | a=6377563.396 | e=.006670540 | australian | a=6378160 | f=1/298.25 | Australia bessel | a=6377397.155 | e=.006674372 | Japan clark66 | a=6378206.4 | b=6356583.8 | N. America everest | a=6377276.345 | e=.0066378466 | India, Burma grs80 | a=6378137 | f=1/298.257 | hayford | a=6378388 | f=1/297 | international| a=6378388 | f=1/297 | Europe krasovsky | a=6378245 | f=1/298.3 | wgs66 | a=6378145 | f=1/298.25 | worldwide cov wgs72 | a=6378135 | f=1/298.26 | worldwide cov wgs84 | a=6378137 | f=1/298.257223563| worldwide cov
155:30:00W 19:35:00N< 165:30:00W 19:35:00N< 145:30:00W 20:00:00N< 135:30:00W 21:00:00N<Output would then be sent to the output file utm.outfile, containing the below Easting and Northing coordinate values and UTM zone designations:
237740.85270818 2167292.1076231 5 447560.64349407 2165450.19058336 3 656921.61734802 2212183.40032627 6 448035.11644906 2322228.3038167 8 end
The spheroids listed above have been used as the basis for a number of different datums. The North American Datum of 1927 (NAD 27) was based on the Clark 1866 ("clark66") spheroid. This was a recent current standard datum for North America. Be aware, however, that a new datum, NAD 83, has been developed using the Geodetic Reference System 1980 spheroid; this is now available in m.ll2u as the "grs80" spheroid. The "wgs66", "wgs72", and "wgs84" spheroids are for worldwide use. The "wgs72" spheroid has been used fairly widely by the Department of Defense (DOD) and is the basis for the World Geodetic System 1972 datum. This datum has also been recently replaced; the new DOD datum is WGS 84 (wgs84). Both datums are available within m.ll2u.
To use spheroids other than those listed here, the user can add lines to the ellipsoid parameter definition file in $GISBASE/etc/ellipse.table.
Read the marginalia of your source map to determine which spheroid was used to produce the map on which you are working.
This program recognizes negative numbers if coordinates are input in decimal degrees rather than in the form of degrees:minutes:seconds.
This program has received only limited testing. It should be used with some caution.
For bessel, airy, everest, and wgs66 ellipsoid parameter values, see:
Thomas O. Seppelin, The Department of Defense World
Geodetic System 1972, presented at the International
Symposium on Problems Related to the Redefinition of
North American Geodetic Networks, Fredericton, New
Brunswick, Canada in May, 1974; see Table 9, p.35.
For wgs84 parameter values, see:
U.S. Naval Oceanographic Labs.
Also read GRASS User's Reference Manual entries for:
d.label
d.points
d.sites
d.where
m.datum.shift
m.gc2ll
m.ll2gc
m.u2ll
parser