TransverseMercatorProj.pod

=head1 NAME

TransverseMercatorProj -- perform transverse Mercator projection

=head1 SYNOPSIS

B<TransverseMercatorProj> [ B<-s> | B<-t> ]
[ B<-l> I<lon0> ] [ B<-k> I<k0> ] [ B<-r> ]
[ B<-e> I<a> I<f> ] [ B<-w> ] [ B<-p> I<prec> ]
[ B<--comment-delimiter> I<commentdelim> ]
[ B<--version> | B<-h> | B<--help> ]
[ B<--input-file> I<infile> | B<--input-string> I<instring> ]
[ B<--line-separator> I<linesep> ]
[ B<--output-file> I<outfile> ]

=head1 DESCRIPTION

Perform the transverse Mercator projections.  Convert geodetic
coordinates to transverse Mercator coordinates.  The central meridian is
given by I<lon0>.  The longitude of origin is the equator.  The scale on
the central meridian is I<k0>.  By default an implementation of the
exact transverse Mercator projection is used.

Geodetic coordinates are provided on standard input as a set of lines
containing (blank separated) I<latitude> and I<longitude> (decimal
degrees or degrees, minutes, seconds); for detils on the allowed
formats for latitude and longitude, see the C<GEOGRAPHIC COORDINATES>
section of GeoConvert(1).  For each set of geodetic coordinates, the
corresponding projected easting, I<x>, and northing, I<y>, (meters) are
printed on standard output together with the meridian convergence
I<gamma> (degrees) and scale I<k>.  The meridian convergence is the
bearing of grid north (the I<y> axis) measured clockwise from true north.

=head1 OPTIONS

=over

=item B<-s>

use the sixth-order Krueger series approximation to the transverse
Mercator projection instead of the exact projection.

=item B<-t>

use the exact algorithm with the L</EXTENDED DOMAIN>.

=item B<-l> I<lon0>

specify the longitude of origin I<lon0> (degrees, default 0).

=item B<-k> I<k0>

specify the scale I<k0> on the central meridian (default 0.9996).

=item B<-r>

perform the reverse projection.  I<x> and I<y> are given on standard
input and each line of standard output gives I<latitude>, I<longitude>,
I<gamma>, and I<k>.

=item B<-e> I<a> I<f>

specify the ellipsoid via the equatorial radius, I<a> and
the flattening, I<f>.  Setting I<f> = 0 results in a sphere.  Specify
I<f> E<lt> 0 for a prolate ellipsoid.  A simple fraction, e.g., 1/297,
is allowed for I<f>.  By default, the WGS84 ellipsoid is used, I<a> =
6378137 m, I<f> = 1/298.257223563.  If the exact algorithm is used, I<f>
must be positive.

=item B<-w>

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

=item B<-p> I<prec>

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

=item B<--comment-delimiter> I<commentdelim>

set the comment delimiter to I<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).

=item B<--version>

print version and exit.

=item B<-h>

print usage and exit.

=item B<--help>

print full documentation and exit.

=item B<--input-file> I<infile>

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

=item B<--input-string> I<instring>

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

=item B<--line-separator> I<linesep>

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

=item B<--output-file> I<outfile>

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

=back

=head1 EXTENDED DOMAIN

The exact transverse Mercator projection has a I<branch point> on the
equator at longitudes (relative to I<lon0>) of +/- (1 - I<e>) 90, where
I<e> is the eccentricity of the ellipsoid.  The standard convention for
handling this branch point is to map positive (negative) latitudes into
positive (negative) northings I<y>; i.e., a branch cut is placed on the
equator.  With the I<extended> domain, the northern sheet of the
projection is extended into the south hemisphere by pushing the branch
cut south from the branch points.  See the reference below for details.

=head1 EXAMPLES

   echo 0 90 | TransverseMercatorProj
   => 25953592.84 9997964.94 90 18.40
   echo 260e5 100e5 | TransverseMercatorProj -r
   => -0.02 90.00 90.01 18.48

=head1 ERRORS

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

=head1 AUTHOR

B<TransverseMercatorProj> was written by Charles Karney.

=head1 SEE ALSO

The algorithms for the transverse Mercator projection are described in
C. F. F. Karney, I<Transverse Mercator with an accuracy of a few
nanometers>, J. Geodesy B<85>(8), 475-485 (Aug. 2011); DOI
L<https://doi.org/10.1007/s00190-011-0445-3>; preprint
L<https://arxiv.org/abs/1002.1417>.  The explanation of the extended
domain of the projection with the B<-t> option is given in Section 5 of
this paper.

=head1 HISTORY

B<TransverseMercatorProj> was added to GeographicLib,
L<https://geographiclib.sourceforge.io>, in 2009-01.
Prior to version 1.9 it was called TransverseMercatorTest (and its
interface was slightly different).