NAME¶

GeoConvert -- convert geographic coordinates

SYNOPSIS¶

GeoConvert [ -g | -d | -: | -u | -m | -c ] [ -p prec ] [ -z zone | -s | -t ] [ -n ] [ -w ] [ --comment-delimiter commentdelim ] [ --version | -h | --help ] [ --input-file infile | --input-string instring ] [ --line-separator linesep ] [ --output-file outfile ]

DESCRIPTION¶

GeoConvert reads from standard input interpreting each line as a geographic coordinate and prints the coordinate in the format specified by the options on standard output. The input is interpreted in one of three different ways depending on how many space or comma delimited tokens there are on the line. The options -g, -d, -u, and -m govern the format of output. In all cases, the WGS84 model of the earth is used ( a = 6378137 m, f = 1/298.257223563).

geographic

2 tokens (output options -g, -d, or -:) given as latitude longitude using decimal degrees or degrees minutes seconds. d, ', and " are used to denote degrees, minutes, and seconds, with the least significant designator optional. (See QUOTING for how to quote the characters ' and " when entering coordinates on the command line.) Various unicode characters (encoded with UTF-8) may also be used to denote degrees, minutes, and seconds, e.g., the degree, prime, and double prime symbols. Alternatively, : (colon) may be used to separate the various components. Latitude is given first (unless the -w option is given); however, on input, either may be given first by appending or prepending N or S to the latitude and E or W to the longitude. For example, the following are all equivalent

 

    33.3 44.4
    E44.4 N33.3
    33d18'N 44d24'E
    44d24 33d18N
    33:18 44:24
    

UTM/UPS

3 tokens (output option -u) given as zone+hemisphere easting northing or easting northing zone+hemisphere, where hemisphere is either N or S. The zone is absent for a UPS specification. For example,

 

    38N 444140.54 3684706.36
    444140.54 3684706.36 38N
    S 2173854.98 2985980.58
    2173854.98 2985980.58 S
    

MRGS

1 token (output option -m) is used to specify the center of an MGRS grid square. For example,

 

    38SMB4484
    38SMB44140847064
    

OPTIONS¶

-g

output latitude and longitude using decimal degrees. Default output mode.

-d

output latitude and longitude using degrees, minutes, and seconds (DMS).

-:

like -d, except use : as a separator instead of the d, ', and " delimiters.

-u

output UTM or UPS.

-m

output MGRS.

-c

output meridian convergence and scale for the corresponding UTM or UPS projection. Convergence is the bearing of grid north given as degrees clockwise from true north.

-p

set the output precision to prec (default 0); prec is the precision relative to 1 m. See PRECISION.

-z

set the zone to zone for output. Use either 0 < zone <= 60 for a UTM zone or zone = 0 for UPS. Alternatively use a zone+hemisphere designation (hemisphere is ignored), e.g., 38N. See ZONE.

-s

use the standard UPS and UTM zones.

-t

similar to -s but forces UPS regions to the closest UTM zone.

-n

on input, MGRS coordinates refer to the south-west corner of the MGRS square instead of the center; see MGRS.

-w

on input and output, longitude precedes latitude (except that on input this can be overridden by a hemisphere designator, N, S,E, W).

--comment-delimiter

set the comment delimiter to commentdelim (e.g., "#" or "//"). If set, the input lines will be scanned for this delimiter and, if found, the delimiter and the rest of the line will be removed prior to processing and subsequently appended to the output line (separated by a space).

--version

print version and exit.

-h

print usage and exit.

--help

print full documentation and exit.

--input-file

read input from the file infile instead of from standard input; a file name of "-" stands for standard input.

--input-string

read input from the string instring instead of from standard input. All occurrences of the line separator character (default is a semicolon) in instring are converted to newlines before the reading begins.

--line-separator

set the line separator character to linesep. By default this is a semicolon.

--output-file

write output to the file outfile instead of to standard output; a file name of "-" stands for standard output.

PRECISION¶

prec gives precision of the output with prec = 0 giving 1 m precision, prec = 3 giving 1 mm precision, etc. prec is the number of digits after the decimal point for UTM/UPS. The number of digits per coordinate for MGRS is 5 + prec. For decimal degrees, the number of digits after the decimal point is 5 + prec. For DMS (degree, minute, seconds) output, the number of digits after the decimal point in the seconds components is 1 + prec; if this is negative then use minutes ( prec = -2 or -3) or degrees ( prec <= -4) as the least significant component. Print convergence, resp. scale, with 5 + prec, resp. 7 + prec, digits after the decimal point. The minimum value of prec is -5 and the maximum is 9 for UTM/UPS, 9 for decimal degrees, 10 for DMS, 6 for MGRS, and 8 for convergence and scale.

MGRS¶

MGRS coordinates represent a square patch of the earth, thus "38SMB4488" is in zone "38N" with 444km <= easting < 445km and 3688km <= northing < 3689km. Consistent with this representation, coordinates are truncated (instead of rounded) to the requested precision. Similarly, on input an MGRS coordinate represents the center of the square ("38N 444500 3688500" in the example above). However, if the -n option is given then the south-west corner of the square is returned instead ("38N 444000 3688000" in the example above).

ZONE¶

If the input is geographic, GeoConvert uses the standard rules of selecting UTM vs UPS and for assigning the UTM zone (with the Norway and Svalbard exceptions). If the input is UTM/UPS, or MGRS, then the choice between UTM and UPS and the UTM zone mirrors the input. The -z zone, -s, -t options allow these rules to be overridden with zone = 0 being used to indicate UPS. For example, the point

   79.9S 6.1E

corresponds to possible MGRS coordinates

   32CMS4324728161 (standard UTM zone = 32)
   31CEM6066227959 (neighboring UTM zone = 31)
     BBZ1945517770 (neighboring UPS zone)

then

   echo 79.9S 6.1E      | GeoConvert -p -3 -m       => 32CMS4328
   echo 31CEM6066227959 | GeoConvert -p -3 -m       => 31CEM6027
   echo 31CEM6066227959 | GeoConvert -p -3 -m -s    => 32CMS4328
   echo 31CEM6066227959 | GeoConvert -p -3 -m -z 0  =>   BBZ1917

NOTE: the letter in the zone specification for UTM is a hemisphere designator N or S and not an MGRS latitude band letter. Convert the MGRS latitude band letter to a hemisphere as follows: replace C thru M by S; replace N thru X by N.

QUOTING¶

Unfortunately the characters ' and " have special meanings in many shells and have to be entered with care.

Unix shells (sh, bash, tsch)

The special characters can be quoted by preceding them with a \ (backslash). Alternatively you can quote a ' with a pair of "s. The two alternatives are illustrated by

 

   echo 30d30\'30\" "30d30'30" | GeoConvert -d -p -1
   => 30d30'30"N 030d30'30"E
    

 

Alternatively use colon separators, e.g., 30:30:30, which need no quoting.

Windows command shell (cmd)

The ' character needs no quoting and the " character can be quoted by a ^. However this quoting is usually unnecessary because the trailing designator can be omitted. Thus

 

   echo 30d30'30^" 30d30'30 | GeoConvert -d -p -1
   => 30d30'30"N 030d30'30"E
    

 

Alternatively use colon separators, e.g., 30:30:30, which need no quoting.

Input from a file

No quoting need be done if the input from a file. Thus each line of the file "input.txt" should just contain the plain coordinates.

 

  GeoConvert -d -p -1 < input.txt
    

EXAMPLES¶

   echo 38SMB4488 | GeoConvert         => 33.33424 44.40363
   echo 38SMB4488 | GeoConvert -: -p 1 => 33:20:03.25N 044:2413.06E
   echo 38SMB4488 | GeoConvert -u      => 38N 444500 3688500
   echo E44d24 N33d20 | GeoConvert -m -p -3 => 38SMB4488

ERRORS¶

An illegal line of input will print an error message to standard output beginning with "ERROR:" and causes GeoConvert to return an exit code of 1. However, an error does not cause GeoConvert to terminate; following lines will be converted.

ABBREVIATIONS¶

UTM

Universal Transverse Mercator, <http://en.wikipedia.org/wiki/Universal_Transverse_Mercator_coordinate_system>.

UPS

Universal Polar Stereographic, <http://en.wikipedia.org/wiki/Universal_Polar_Stereographic>.

MGRS

Military Grid Reference System, <http://en.wikipedia.org/wiki/Military_grid_reference_system>.

WGS84

World Geodetic System 1984, <http://en.wikipedia.org/wiki/WGS84>.

SEE ALSO¶

The algorithms for the transverse Mercator projection are described in C. F. F. Karney, Transverse Mercator with an accuracy of a few nanometers, J. Geod 85(8), 475-485 (Aug. 2011); DOI http://dx.doi.org/10.1007/s00190-011-0445-3 <http://dx.doi.org/10.1007/s00190-011-0445-3>; preprint <http://arxiv.org/abs/1002.1417>.

AUTHOR¶

GeoConvert was written by Charles Karney.

HISTORY¶

GeoConvert was added to GeographicLib, <http://geographiclib.sf.net>, in 2009-01.