NAME

       GeodesicProj -- perform projections based on geodesics

SYNOPSIS

       GeodesicProj ( -z | -c | -g ) lat0 lon0 [ -r ] [ -e a f ] [ -w ] [ -p prec ] [
       --comment-delimiter commentdelim ] [ --version | -h | --help ] [ --input-file infile |
       --input-string instring ] [ --line-separator linesep ] [ --output-file outfile ]

DESCRIPTION

       Perform projections based on geodesics.  Convert geodetic coordinates to either azimuthal
       equidistant, Cassini-Soldner, or gnomonic coordinates.  The center of the projection
       (lat0, lon0) is specified by either the -c option (for Cassini-Soldner), the -z option
       (for azimuthal equidistant), or the -g option (for gnomonic).  At least one of these
       options must be given (the last one given is used).

       Geodetic coordinates are provided on standard input as a set of lines containing (blank
       separated) latitude and longitude (decimal degrees or degrees, minutes, seconds); for
       details on the allowed formats for latitude and longitude, see the "GEOGRAPHIC
       COORDINATES" section of GeoConvert(1).  For each set of geodetic coordinates, the
       corresponding projected coordinates x, y (meters) are printed on standard output together
       with the azimuth azi (degrees) and reciprocal scale rk.  For Cassini-Soldner, azi is the
       bearing of the easting direction and the scale in the easting direction is 1 and the scale
       in the northing direction is 1/rk.  For azimuthal equidistant and gnomonic, azi is the
       bearing of the radial direction and the scale in the azimuthal direction is 1/rk.  For
       azimuthal equidistant and gnomonic, the scales in the radial direction are 1 and 1/rk^2,
       respectively.

OPTIONS

       -z lat0 lon0
           use the azimuthal equidistant projection centered at latitude = lat0, longitude =
           lon0.  The -w flag can be used to swap the default order of the 2 coordinates,
           provided that it appears before -z.

       -c lat0 lon0
           use the Cassini-Soldner projection centered at latitude = lat0, longitude = lon0.  The
           -w flag can be used to swap the default order of the 2 coordinates, provided that it
           appears before -c.

       -g lat0 lon0
           use the ellipsoidal gnomonic projection centered at latitude = lat0, longitude = lon0.
           The -w flag can be used to swap the default order of the 2 coordinates, provided that
           it appears before -g.

       -r  perform the reverse projection.  x and y are given on standard input and each line of
           standard output gives latitude, longitude, azi, and rk.

       -e a f
           specify the ellipsoid via the equatorial radius, a and the flattening, f.  Setting f =
           0 results in a sphere.  Specify f < 0 for a prolate ellipsoid.  A simple fraction,
           e.g., 1/297, is allowed for f.  By default, the WGS84 ellipsoid is used, a = 6378137
           m, f = 1/298.257223563.

       -w  toggle the longitude first flag (it starts off); if the flag is on, then on input and
           output, longitude precedes latitude (except that, on input, this can be overridden by
           a hemisphere designator, N, S, E, W).

       -p prec
           set the output precision to prec (default 6).  prec is the number of digits after the
           decimal point for lengths (in meters).  For latitudes, longitudes, and azimuths (in
           degrees), the number of digits after the decimal point is prec + 5.  For the scale,
           the number of digits after the decimal point is prec + 6.

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

       --input-string instring
           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 linesep
           set the line separator character to linesep.  By default this is a semicolon.

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

EXAMPLES

          echo 48.648 -2.007 | GeodesicProj -c 48.836 2.337
          => -319919 -11791 86.7 0.999
          echo -319919 -11791 | GeodesicProj -c 48.836 2.337 -r
          => 48.648 -2.007 86.7 0.999

ERRORS

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

SEE ALSO

       The ellipsoidal gnomonic projection is derived in Section 8 of C. F. F. Karney, Algorithms
       for geodesics, J. Geodesy 87, 43-55 (2013); DOI
       <https://doi.org/10.1007/s00190-012-0578-z>; addenda:
       <https://geographiclib.sourceforge.io/geod-addenda.html>.

AUTHOR

       GeodesicProj was written by Charles Karney.

HISTORY

       GeodesicProj was added to GeographicLib, <https://geographiclib.sourceforge.io>, in
       2009-08.  Prior to version 1.9 it was called EquidistantTest.