NAME¶
GeodesicProj -- perform projections based on geodesics
SYNOPSIS¶
GeodesicProj (
-z |
-c |
-g )
lat0
lon0 [
-r ] [
-e a f ] [
-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 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 f; the equatorial radius is
a and the flattening is 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. (Also, if f > 1,
the flattening is set to 1/ f.) By default, the WGS84 ellipsoid is
used, a = 6378137 m, f = 1/298.257223563.
- -p
- 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
- 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.
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
<
http://dx.doi.org/10.1007/s00190-012-0578-z>; addenda:
<
http://geographiclib.sf.net/geod-addenda.html>.
AUTHOR¶
GeodesicProj was written by Charles Karney.
HISTORY¶
GeodesicProj was added to GeographicLib,
<
http://geographiclib.sf.net>, in 2009-08. Prior to version 1.9 it was
called EquidistantTest.