NAME

EquidistantTest -- perform projections based on geodesics


SYNOPSIS

EquidistantTest ( -z | -c | -g ) lat0 lon0 [ -r ] [ -e a r ] [ --version | -h | --help ]


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 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

use the azimuthal equidistant projection centered at latitude = lat0, longitude = lon0.

-c

use the Cassini-Soldner projection centered at latitude = lat0, longitude = lon0.

-g

use the ellipsoidal gnomonic projection centered at latitude = lat0, longitude = lon0.

-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

specify the ellipsoid via a r; the equatorial radius is a and the reciprocal flattening is r. Setting r = 0 results in a sphere. Specify r < 0 for a prolate ellipsoid. By default, the WGS84 ellipsoid is used, a = 6378137m, r = 298.257223563.

--version

print version.

-h

print usage.

--help

print full documentation.


EXAMPLES

   echo 48.648 -2.007 | EquidistantTest -c 48.836 2.337
   => -319919 -11791 86.7 0.999
   echo -319919 -11791 | EquidistantTest -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 EquidistantTest to return an exit code of 1. However, an error does not cause EquidistantTest to terminate; following lines will be converted.


SEE ALSO

EquidistantTest is a part of GeographicLib, http://geographiclib.sf.net. The ellipsoidal gnomonic projection is derived in Section 13 of C. F. F. Karney, Geodesics on an ellipsoid of revolution, Feb. 2011; preprint http://arxiv.org/abs/1102.1215.


AUTHOR

EquidistantTest was written by Charles Karney.