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GEODESICPROJ(1) |
GeographicLib Utilities |
GEODESICPROJ(1) |
GeodesicProj -- perform projections based on geodesics
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
]
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.
- -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.
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
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.
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>.
GeodesicProj was written by Charles Karney.
GeodesicProj was added to GeographicLib,
<https://geographiclib.sourceforge.io>, in 2009-08. Prior to version 1.9
it was called EquidistantTest.
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