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<title>GRDCONTOUR</title>
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<h1 align="center">GRDCONTOUR</h1>
<a href="#NAME">NAME</a><br>
<a href="#SYNOPSIS">SYNOPSIS</a><br>
<a href="#DESCRIPTION">DESCRIPTION</a><br>
<a href="#OPTIONS">OPTIONS</a><br>
<a href="#ASCII FORMAT PRECISION">ASCII FORMAT PRECISION</a><br>
<a href="#FILE FORMATS">FILE FORMATS</a><br>
<a href="#EXAMPLES">EXAMPLES</a><br>
<a href="#SEE ALSO">SEE ALSO</a><br>
<hr>
<h2>NAME
<a name="NAME"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em">grdcontour
− Contouring of 2-D gridded data sets</p>
<h2>SYNOPSIS
<a name="SYNOPSIS"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em"><b>grdcontour</b>
<i>grdfile</i> <b>−C</b><i>cont_int</i>
<b>−J</b><i>parameters</i> [
<b>−A</b>[<b>-</b>|<i>annot_int</i>][<i>labelinfo</i>]
] [ <b>−B</b>[<b>p</b>|<b>s</b>]<i>parameters</i> ] [
<b>−D</b><i>dumpfile</i> ] [
<b>−E</b><i>azimuth/elevation</i> ] [
<b>−F</b>[<b>l</b>|<b>r</b>] ] [
<b>−G</b>[<b>d</b>|<b>f</b>|<b>n</b>|<b>l</b>|<b>L</b>|<b>x</b>|<b>X</b>]<i>params</i>
] [ <b>−K</b> ] [ <b>−L</b><i>low/high</i> ] [
<b>−O</b> ] [ <b>−P</b> ] [
<b>−Q</b><i>cut</i> ] [
<b>−R</b><i>west</i>/<i>east</i>/<i>south</i>/<i>north</i>[<b>r</b>]
] [ <b>−S</b><i>smoothfactor</i> ] [
<b>−T</b>[<b>+|-</b>][<i>gap/length</i>][<b>:</b><i>LH</i>]
] [
<b>−U</b>[<i>just</i>/<i>dx</i>/<i>dy</i>/][<b>c</b>|<i>label</i>]
] [ <b>−V</b> ] [
<b>−W</b>[<b>+</b>][<i>type</i>]<i>pen</i> ] [
<b>−X</b>[<b>a</b>|<b>c</b>|<b>r</b>][<i>x-shift</i>[<b>u</b>]]
] [
<b>−Y</b>[<b>a</b>|<b>c</b>|<b>r</b>][<i>y-shift</i>[<b>u</b>]]
] [ <b>−Z</b>[<i>factor</i>[/<i>shift</i>]][<b>p</b>]
] [ <b>−c</b><i>copies</i> ] [
<b>−bo</b>[<b>s</b>|<b>S</b>|<b>d</b>|<b>D</b>[<i>ncol</i>]|<b>c</b>[<i>var1</i><b>/</b><i>...</i>]]
] [ <b>−m</b>[<i>flag</i>] ]</p>
<h2>DESCRIPTION
<a name="DESCRIPTION"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em"><b>grdcontour</b>
reads a 2-D grid file and produces a contour map by tracing
each contour through the grid. As an option, the x/y/z
positions of the contour lines may be dumped to a single
multisegment file or many separate files. <i>PostScript</i>
code is generated and sent to standard output. Various
options that affect the plotting are available. <i><br>
grdfile</i></p>
<p style="margin-left:22%;">2-D gridded data set to be
contoured. (See GRID FILE FORMATS below).</p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p><b>−C</b></p></td>
<td width="8%"></td>
<td width="78%">
<p>The contours to be drawn may be specified in one of
three possible ways:</p></td></tr>
</table>
<p style="margin-left:22%;">(1) If <i>cont_int</i> has the
suffix ".cpt" and can be opened as a file, it is
assumed to be a color palette table. The color boundaries
are then used as contour levels. If the cpt-file has
annotation flags in the last column then those contours will
be annotated. By default all contours are labeled; use
<b>−A−</b> to disable all annotations. <br>
(2) If <i>cont_int</i> is a file but not a cpt-file, it is
expected to contain contour levels in column 1 and a
C(ontour) OR A(nnotate) in col 2. The levels marked C (or c)
are contoured, the levels marked A (or a) are contoured and
annotated. Optionally, a third column may be present and
contain the fixed annotation angle for this contour level.
<br>
(3) If no file is found, then <i>cont_int</i> is interpreted
as a constant contour interval. If <b>−A</b> is set
and <b>−C</b> is not, then the contour interval is set
equal to the specified annotation interval. <br>
If a file is given and <b>−T</b> is set, then only
contours marked with upper case C or A will have tickmarks.
In all cases the contour values have the same units as the
grid.</p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em"><b>−J</b></p></td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em">Selects the map projection.
Scale is UNIT/degree, 1:xxxxx, or width in UNIT (upper case
modifier). UNIT is cm, inch, or m, depending on the
<b><A HREF="gmtdefaults.html#MEASURE_UNIT">MEASURE_UNIT</A></b> setting in .gmtdefaults4, but this can
be overridden on the command line by appending <b>c</b>,
<b>i</b>, or <b>m</b> to the scale/width value. When central
meridian is optional, default is center of longitude range
on <b>−R</b> option. Default standard parallel is the
equator. For map height, max dimension, or min dimension,
append <b>h</b>, <b>+</b>, or <b>-</b> to the width,
respectively.</p> </td></tr>
</table>
<p style="margin-left:22%;">More details can be found in
the <b><A HREF="psbasemap.html">psbasemap</A></b> man pages.</p>
<p style="margin-left:22%; margin-top: 1em"><b>CYLINDRICAL
PROJECTIONS:</b></p>
<p style="margin-left:22%; margin-top: 1em"><b>−Jc</b><i>lon0/lat0/scale</i>
(Cassini) <b><br>
−Jcyl_stere</b>/[<i>lon0/</i>[<i>lat0/</i>]]<i>scale</i>
(Cylindrical Stereographic) <b><br>
−Jj</b>[<i>lon0/</i>]<i>scale</i> (Miller) <b><br>
−Jm</b>[<i>lon0</i>/[<i>lat0/</i>]]<i>scale</i>
(Mercator) <b><br>
−Jm</b><i>lon0/lat0/scale</i> (Mercator - Give
meridian and standard parallel) <b><br>
−Jo</b>[<b>a</b>]<i>lon0/lat0/azimuth/scale</i>
(Oblique Mercator - point and azimuth) <b><br>
−Jo</b>[<b>b</b>]<i>lon0/lat0/lon1/lat1/scale</i>
(Oblique Mercator - two points) <b><br>
−Joc</b><i>lon0/lat0/lonp/latp/scale</i> (Oblique
Mercator - point and pole) <b><br>
−Jq</b>[<i>lon0/</i>[<i>lat0/</i>]]<i>scale</i>
(Cylindrical Equidistant) <b><br>
−Jt</b><i>lon0/</i>[<i>lat0/</i>]<i>scale</i> (TM -
Transverse Mercator) <b><br>
−Ju</b><i>zone/scale</i> (UTM - Universal Transverse
Mercator) <b><br>
−Jy</b>[<i>lon0/</i>[<i>lat0/</i>]]<i>scale</i>
(Cylindrical Equal-Area)</p>
<p style="margin-left:22%; margin-top: 1em"><b>CONIC
PROJECTIONS:</b></p>
<p style="margin-left:22%; margin-top: 1em"><b>−Jb</b><i>lon0/lat0/lat1/lat2/scale</i>
(Albers) <b><br>
−Jd</b><i>lon0/lat0/lat1/lat2/scale</i> (Conic
Equidistant) <b><br>
−Jl</b><i>lon0/lat0/lat1/lat2/scale</i> (Lambert Conic
Conformal) <b><br>
−Jpoly</b>/[<i>lon0/</i>[<i>lat0/</i>]]<i>scale</i>
((American) Polyconic)</p>
<p style="margin-left:22%; margin-top: 1em"><b>AZIMUTHAL
PROJECTIONS:</b></p>
<p style="margin-left:22%; margin-top: 1em"><b>−Ja</b><i>lon0/lat0</i>[<i>/horizon</i>]<i>/scale</i>
(Lambert Azimuthal Equal-Area) <b><br>
−Je</b><i>lon0/lat0</i>[<i>/horizon</i>]<i>/scale</i>
(Azimuthal Equidistant) <b><br>
−Jf</b><i>lon0/lat0</i>[<i>/horizon</i>]<i>/scale</i>
(Gnomonic) <b><br>
−Jg</b><i>lon0/lat0</i>[<i>/horizon</i>]<i>/scale</i>
(Orthographic) <b><br>
−Jg</b><i>lon0/lat0/altitude/azimuth/tilt/twist/Width/Height/scale</i>
(General Perspective). <b><br>
−Js</b><i>lon0/lat0</i>[<i>/horizon</i>]<i>/scale</i>
(General Stereographic)</p>
<p style="margin-left:22%; margin-top: 1em"><b>MISCELLANEOUS
PROJECTIONS:</b></p>
<p style="margin-left:22%; margin-top: 1em"><b>−Jh</b>[<i>lon0/</i>]<i>scale</i>
(Hammer) <b><br>
−Ji</b>[<i>lon0/</i>]<i>scale</i> (Sinusoidal) <b><br>
−Jkf</b>[<i>lon0/</i>]<i>scale</i> (Eckert IV) <b><br>
−Jk</b>[<b>s</b>][<i>lon0/</i>]<i>scale</i> (Eckert
VI) <b><br>
−Jn</b>[<i>lon0/</i>]<i>scale</i> (Robinson) <b><br>
−Jr</b>[<i>lon0/</i>]<i>scale</i> (Winkel Tripel)
<b><br>
−Jv</b>[<i>lon0/</i>]<i>scale</i> (Van der Grinten)
<b><br>
−Jw</b>[<i>lon0/</i>]<i>scale</i> (Mollweide)</p>
<p style="margin-left:22%; margin-top: 1em"><b>NON-GEOGRAPHICAL
PROJECTIONS:</b></p>
<p style="margin-left:22%; margin-top: 1em"><b>−Jp</b>[<b>a</b>]<i>scale</i>[<i>/origin</i>][<b>r</b>|<b>z</b>]
(Polar coordinates (theta,r)) <b><br>
−Jx</b><i>x-scale</i>[<b>d</b>|<b>l</b>|<b>p</b><i>pow</i>|<b>t</b>|<b>T</b>][<i>/y-scale</i>[<b>d</b>|<b>l</b>|<b>p</b><i>pow</i>|<b>t</b>|<b>T</b>]]
(Linear, log, and power scaling)</p>
<h2>OPTIONS
<a name="OPTIONS"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em">No space
between the option flag and the associated arguments.</p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em"><b>−A</b></p></td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em"><i>annot_int</i> is annotation
interval in data units; it is ignored if contour levels are
given in a file. [Default is no annotations]. Append
<b>-</b> to disable all annotations implied by
<b>−C</b>. The optional <i>labelinfo</i> controls the
specifics of the label formatting and consists of a
concatenated string made up of any of the following control
arguments:</p> </td></tr>
</table>
<p style="margin-left:22%;"><b>+a</b><i>angle</i></p>
<p style="margin-left:32%;">For annotations at a fixed
angle, <b>+an</b> for line-normal, or <b>+ap</b> for
line-parallel [Default]. By appending the <b>u</b> or
<b>d</b> we get annotations whose top face the next upper or
lower annotation, respectively.</p>
<p style="margin-left:22%;"><b>+c</b><i>dx</i>[/<i>dy</i>]</p>
<p style="margin-left:32%;">Sets the clearance between
label and optional text box. Append <b>c|i|m|p</b> to
specify the unit or % to indicate a percentage of the label
font size [15%].</p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="22%"></td>
<td width="9%">
<p><b>+d</b></p></td>
<td width="1%"></td>
<td width="68%">
<p>Turns on debug which will draw helper points and lines
to illustrate the workings of the quoted line setup.</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="9%">
<p><b>+f</b><i>font</i></p></td>
<td width="1%"></td>
<td width="68%">
<p>Sets the desired font [Default
<b><A HREF="gmtdefaults.html#ANNOT_FONT_PRIMARY">ANNOT_FONT_PRIMARY</A></b>].</p> </td></tr>
</table>
<p style="margin-left:22%;"><b>+g</b>[<i>color</i>]</p>
<p style="margin-left:32%;">Selects opaque text boxes
[Default is transparent]; optionally specify the color
[Default is <b><A HREF="gmtdefaults.html#PAGE_COLOR">PAGE_COLOR</A></b>]. (See SPECIFYING COLOR
below).</p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="22%"></td>
<td width="9%">
<p><b>+j</b><i>just</i></p></td>
<td width="1%"></td>
<td width="68%">
<p>Sets label justification [Default is MC]. Ignored when
-SqN|n+|-1 is used.</p></td></tr>
</table>
<p style="margin-left:22%;"><b>+k</b><i>color</i></p>
<p style="margin-left:32%;">Sets color of text labels
[Default is <b><A HREF="gmtdefaults.html#COLOR_BACKGROUND">COLOR_BACKGROUND</A></b>]. (See SPECIFYING COLOR
below).</p>
<p style="margin-left:22%;"><b>+n</b><i>dx</i>[/<i>dy</i>]</p>
<p style="margin-left:32%;">Nudges the placement of labels
by the specified amount (append <b>c|i|m|p</b> to specify
the units). Increments are considered in the coordinate
system defined by the orientation of the line; use <b>+N</b>
to force increments in the plot x/y coordinates system [no
nudging].</p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="22%"></td>
<td width="3%">
<p><b>+o</b></p></td>
<td width="7%"></td>
<td width="68%">
<p>Selects rounded rectangular text box [Default is
rectangular]. Not applicable for curved text (<b>+v</b>) and
only makes sense for opaque text boxes.</p></td></tr>
</table>
<p style="margin-left:22%;"><b>+p</b>[<i>pen</i>]</p>
<p style="margin-left:32%;">Draws the outline of text
boxsets [Default is no outline]; optionally specify pen for
outline [Default is width = 0.25p, color = black, texture =
solid]. (See SPECIFYING PENS below).</p>
<p style="margin-left:22%;"><b>+r</b><i>min_rad</i></p>
<p style="margin-left:32%;">Will not place labels where the
line’s radius of curvature is less than <i>min_rad</i>
[Default is 0].</p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="22%"></td>
<td width="9%">
<p><b>+s</b><i>size</i></p></td>
<td width="1%"></td>
<td width="68%">
<p>Sets the desired font size in points [Default is 9].</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="9%">
<p><b>+u</b><i>unit</i></p></td>
<td width="1%"></td>
<td width="68%">
<p>Appends <i>unit</i> to all line labels. If <i>unit</i>
starts with a leading hyphen (-) then there will be no space
between label value and the unit. If <i>z</i> is appended we
use the unit specified in the grid file. [Default is no
unit].</p> </td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="9%">
<p><b>+v</b></p></td>
<td width="1%"></td>
<td width="68%">
<p>Specifies curved labels following the path [Default is
straight labels].</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="9%">
<p><b>+w</b></p></td>
<td width="1%"></td>
<td width="68%">
<p>Specifies how many (<i>x, y</i>) points will be used to
estimate label angles [Default is 10].</p></td></tr>
</table>
<p style="margin-left:22%;"><b>+=</b><i>prefix</i></p>
<p style="margin-left:32%;">Prepends <i>prefix</i> to all
line labels. If <i>prefix</i> starts with a leading hyphen
(-) then there will be no space between label value and the
prefix. [Default is no prefix].</p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p><b>−B</b></p></td>
<td width="8%"></td>
<td width="78%">
<p>Sets map boundary annotation and tickmark intervals; see
the <b><A HREF="psbasemap.html">psbasemap</A></b> man page for all the details.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p><b>−D</b></p></td>
<td width="8%"></td>
<td width="78%">
<p>Dump the (x,y,z) coordinates of each contour to separate
files, one for each contour segment. The files will be named
<i>dumpfile_cont_segment[_i]</i>.xyz (or <i>.b</i> is
<b>−b</b> is selected), where <i>cont</i> is the
contour value and <i>segment</i> is a running segment number
for each contour interval (for closed contours we append
_i.) If the prefix is given as ’-’ the file
names are instead <i>C#_i</i> (interior) or <i>C#_e</i>
(external) plus extension, and # is just a running number.
This allows us to make short file names that will work with
GNU utilities under DOS. However, when <b>−m</b> is
used in conjunction with <b>−D</b> a single
multisegment file is created instead.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p><b>−E</b></p></td>
<td width="8%"></td>
<td width="78%">
<p>Sets the viewpoint’s azimuth and elevation (for
perspective view) [180/90]. For frames used for animation,
you may want to append <b>+</b> to fix the center of your
data domain (or specify a particular world coordinate point
with <b>+w</b><i>lon0</i>/<i>lat</i>[/<i>z</i>]) which will
project to the center of your page size (or specify the
coordinates of the projected view point with
<b>+v</b><i>x0</i>/<i>y0).</i></p> </td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p><b>−F</b></p></td>
<td width="8%"></td>
<td width="78%">
<p>Force dumped contours to be oriented so that higher
z-values are to the left (<b>−Fl</b> [Default]) or
right (<b>-Fr</b>) as we move along the contour [Default is
arbitrary orientation]. Requires <b>−D</b>.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p><b>−G</b></p></td>
<td width="8%"></td>
<td width="78%">
<p>Controls the placement of labels along the contours.
Choose among five controlling algorithms:</p></td></tr>
</table>
<p style="margin-left:22%;"><b>−Gd</b><i>dist</i>[<b>c</b>|<b>i</b>|<b>m</b>|<b>p</b>]
or
<b>−GD</b><i>dist</i>[<b>d</b>|<b>e</b>|<b>k</b>|<b>m</b>|<b>n</b>]</p>
<p style="margin-left:32%;">For lower case <b>d</b>, give
distances between labels on the plot in your preferred
measurement unit <b>c</b> (cm), <b>i</b> (inch), <b>m</b>
(meter), or <b>p</b> (points), while for upper case
<b>D</b>, specify distances in map units and append the
unit; choose among <b>e</b> (m), <b>k</b> (km), <b>m</b>
(mile), <b>n</b> (nautical mile), or <b>d</b> (spherical
degree). [Default is 10<b>c</b> or 4<b>i</b>].</p>
<p style="margin-left:22%;"><b>−Gf</b><i>ffile.d</i></p>
<p style="margin-left:32%;">Reads the ascii file
<i>ffile.d</i> and places labels at locations in the file
that matches locations along the contours. Inexact matches
and points outside the region are skipped.</p>
<p style="margin-left:22%;"><b>−Gl|L</b><i>line1</i>[,<i>line2</i>,...]</p>
<p style="margin-left:32%;">Give <i>start</i> and
<i>stop</i> coordinates for one or more comma-separated
straight line segments. Labels will be placed where these
lines intersect the contours. The format of each <i>line</i>
specification is <i>start/stop</i>, where <i>start</i> and
<i>stop</i> are either a specified point <i>lon/lat</i> or a
2-character <b>XY</b> key that uses the justification format
employed in <b><A HREF="pstext.html">pstext</A></b> to indicate a point on the map,
given as [LCR][BMT]. In addition, you may use Z+ and Z-
which correspond to the locations of the global max and min
locations in the grid, respectively. <b>−GL</b> will
interpret the point pairs as defining great circles [Default
is straight line].</p>
<p style="margin-left:22%;"><b>−Gn</b><i>n_label</i></p>
<p style="margin-left:32%;">Specifies the number of
equidistant labels for contours line [1]. Upper case
<b>−GN</b> starts labeling exactly at the start of the
line [Default centers them along the line].
<b>−GN</b>-1 places one justified label at start,
while <b>−GN</b>+1 places one justified label at the
end of contours. Optionally, append
/<i>min_dist</i>[c|i|m|p] to enforce that a minimum distance
separation between successive labels is enforced.</p>
<p style="margin-left:22%;"><b>−Gx|X</b><i>xfile.d</i></p>
<p style="margin-left:32%;">Reads the multi-segment file
<i>xfile.d</i> and places labels at the intersections
between the contours and the lines in<i>xfile.d</i>.
<b>−GX</b> will resample the lines first along
great-circle arcs.</p>
<p style="margin-left:22%; margin-top: 1em">In addition,
you may optionally append
<b>+r</b><i>radius</i>[<b>c</b>|<b>i</b>|<b>m</b>|<b>p</b>]
to set a minimum label separation in the x-y plane [no
limitation].</p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p><b>−K</b></p></td>
<td width="4%"></td>
<td width="78%">
<p>More <i>PostScript</i> code will be appended later
[Default terminates the plot system].</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p><b>−L</b></p></td>
<td width="4%"></td>
<td width="78%">
<p>Limit range: Do not draw contours for data values below
<i>low</i> or above <i>high</i>.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p><b>−O</b></p></td>
<td width="4%"></td>
<td width="78%">
<p>Selects Overlay plot mode [Default initializes a new
plot system].</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p><b>−P</b></p></td>
<td width="4%"></td>
<td width="78%">
<p>Selects Portrait plotting mode [Default is Landscape,
see <b><A HREF="gmtdefaults.html">gmtdefaults</A></b> to change this].</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p><b>−Q</b></p></td>
<td width="4%"></td>
<td width="78%">
<p>Do not draw contours with less than <i>cut</i> number of
points [Draw all contours].</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p><b>−R</b></p></td>
<td width="4%"></td>
<td width="78%">
<p><i>xmin</i>, <i>xmax</i>, <i>ymin</i>, and <i>ymax</i>
specify the Region of interest. For geographic regions,
these limits correspond to <i>west, east, south,</i> and
<i>north</i> and you may specify them in decimal degrees or
in [+-]dd:mm[:ss.xxx][W|E|S|N] format. Append <b>r</b> if
lower left and upper right map coordinates are given instead
of w/e/s/n. The two shorthands <b>−Rg</b> and
<b>−Rd</b> stand for global domain (0/360 and
-180/+180 in longitude respectively, with -90/+90 in
latitude). Alternatively, specify the name of an existing
grid file and the <b>−R</b> settings (and grid
spacing, if applicable) are copied from the grid. For
calendar time coordinates you may either give (a) relative
time (relative to the selected <b><A HREF="gmtdefaults.html#TIME_EPOCH">TIME_EPOCH</A></b> and in the
selected <b><A HREF="gmtdefaults.html#TIME_UNIT">TIME_UNIT</A></b>; append <b>t</b> to
<b>−JX</b>|<b>x</b>), or (b) absolute time of the form
[<i>date</i>]<b>T</b>[<i>clock</i>] (append <b>T</b> to
<b>−JX</b>|<b>x</b>). At least one of <i>date</i> and
<i>clock</i> must be present; the <b>T</b> is always
required. The <i>date</i> string must be of the form
[-]yyyy[-mm[-dd]] (Gregorian calendar) or yyyy[-Www[-d]]
(ISO week calendar), while the <i>clock</i> string must be
of the form hh:mm:ss[.xxx]. The use of delimiters and their
type and positions must be exactly as indicated (however,
input, output and plot formats are customizable; see
<b><A HREF="gmtdefaults.html">gmtdefaults</A></b>). [Default is region defined in the grid
file].</p> </td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p><b>−S</b></p></td>
<td width="4%"></td>
<td width="78%">
<p>Used to resample the contour lines at roughly every
(gridbox_size/<i>smoothfactor</i>) interval.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p><b>−T</b></p></td>
<td width="4%"></td>
<td width="78%">
<p>Will draw tickmarks pointing in the downward direction
every <i>gap</i> along the innermost closed contours. Append
<i>gap</i> and tickmark length or use defaults
[0.5<b>c</b>/0.1c or 0.2<b>i</b>/0.04i]. User may choose to
tick only local highs or local lows by specifying
<b>−T+</b> or <b>−T−</b>, respectively.
Appending <b>:LH</b> will plot the characters L and H at the
center of closed innermost contours (local lows and highs).
L and H can be any single character (e.g., LH, -+, etc.) If
a file is given by <b>−C</b> and <b>−T</b> is
set, then only contours marked with upper case C or A will
have tickmarks [and annotation].</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p><b>−U</b></p></td>
<td width="4%"></td>
<td width="78%">
<p>Draw Unix System time stamp on plot. By adding
<i>just/dx/dy/</i>, the user may specify the justification
of the stamp and where the stamp should fall on the page
relative to lower left corner of the plot. For example,
BL/0/0 will align the lower left corner of the time stamp
with the lower left corner of the plot. Optionally, append a
<i>label</i>, or <b>c</b> (which will plot the command
string.). The <b><A HREF="GMT.html">GMT</A></b> parameters <b><A HREF="gmtdefaults.html#UNIX_TIME">UNIX_TIME</A></b>,
<b><A HREF="gmtdefaults.html#UNIX_TIME_POS">UNIX_TIME_POS</A></b>, and <b><A HREF="gmtdefaults.html#UNIX_TIME_FORMAT">UNIX_TIME_FORMAT</A></b> can affect
the appearance; see the <b><A HREF="gmtdefaults.html">gmtdefaults</A></b> man page for
details. The time string will be in the locale set by the
environment variable <b>TZ</b> (generally local time).</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p><b>−V</b></p></td>
<td width="4%"></td>
<td width="78%">
<p>Selects verbose mode, which will send progress reports
to stderr [Default runs "silently"].</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p><b>−W</b></p></td>
<td width="4%"></td>
<td width="78%">
<p><i>type</i>, if present, can be <b>a</b> for annotated
contours or <b>c</b> for regular contours [Default].
<i>pen</i> sets the attributes for the particular line.
Default values for annotated contours: width = 0.75p, color
= black, texture = solid. Regular contours have default
width = 0.25p. (See SPECIFYING PENS below). If the <b>+</b>
flag is specified then the color of the contour lines are
taken from the cpt file (see <b>−C</b>).</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p><b>−X −Y</b></p></td>
<td width="4%"></td>
<td width="78%">
<p>Shift plot origin relative to the current origin by
(<i>x-shift,y-shift</i>) and optionally append the length
unit (<b>c</b>, <b>i</b>, <b>m</b>, <b>p</b>). You can
prepend <b>a</b> to shift the origin back to the original
position after plotting, or prepend <b>r</b> [Default] to
reset the current origin to the new location. If
<b>−O</b> is used then the default
(<i>x-shift,y-shift</i>) is (0,0), otherwise it is (r1i,
r1i) or (r2.5c, r2.5c). Alternatively, give <b>c</b> to
align the center coordinate (x or y) of the plot with the
center of the page based on current page size.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p><b>−Z</b></p></td>
<td width="4%"></td>
<td width="78%">
<p>Use to subtract <i>shift</i> from the data and multiply
the results by <i>factor</i> before contouring starts [1/0].
(Numbers in <b>−A</b>, <b>−C</b>,
<b>−L</b> refer to values after scaling and
translation have occurred.) Append <b>p</b> to indicate that
this grid file contains z-values that are periodic in 360
degrees (e.g., phase data, angular distributions) and that
special precautions must be taken when determining
0-contours.</p> </td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p><b>−bo</b></p></td>
<td width="4%"></td>
<td width="78%">
<p>Selects binary output. Append <b>s</b> for single
precision [Default is <b>d</b> (double)]. Uppercase <b>S</b>
or <b>D</b> will force byte-swapping. Optionally, append
<i>ncol</i>, the number of desired columns in your binary
output file.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p><b>−c</b></p></td>
<td width="4%"></td>
<td width="78%">
<p>Specifies the number of plot copies. [Default is 1].</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p><b>−f</b></p></td>
<td width="4%"></td>
<td width="78%">
<p>Special formatting of input and/or output columns (time
or geographical data). Specify <b>i</b> or <b>o</b> to make
this apply only to input or output [Default applies to
both]. Give one or more columns (or column ranges) separated
by commas. Append <b>T</b> (absolute calendar time),
<b>t</b> (relative time in chosen <b><A HREF="gmtdefaults.html#TIME_UNIT">TIME_UNIT</A></b> since
<b><A HREF="gmtdefaults.html#TIME_EPOCH">TIME_EPOCH</A></b>), <b>x</b> (longitude), <b>y</b>
(latitude), or <b>f</b> (floating point) to each column or
column range item. Shorthand
<b>−f</b>[<b>i</b>|<b>o</b>]<b>g</b> means
<b>−f</b>[<b>i</b>|<b>o</b>]0<b>x</b>,1<b>y</b>
(geographic coordinates).</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p><b>−m</b></p></td>
<td width="4%"></td>
<td width="78%">
<p>When used in conjunction with <b>−D</b> a single
multisegment file is created, and each contour section is
preceded by a header record whose first column is
<i>flag</i> followed by the contour level.</p></td></tr>
</table>
<p style="margin-left:11%; margin-top: 1em"><b>SPECIFYING
PENS</b></p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="4%">
<p style="margin-top: 1em"><i>pen</i></p></td>
<td width="7%"></td>
<td width="78%">
<p style="margin-top: 1em">The attributes of lines and
symbol outlines as defined by <i>pen</i> is a comma
delimetered list of <i>width</i>, <i>color</i> and
<i>texture</i>, each of which is optional. <i>width</i> can
be indicated as a measure (points, centimeters, inches) or
as <b>faint</b>, <b>thin</b>[<b>ner</b>|<b>nest</b>],
<b>thick</b>[<b>er</b>|<b>est</b>],
<b>fat</b>[<b>ter</b>|<b>test</b>], or <b>obese</b>.
<i>color</i> specifies a gray shade or color (see SPECIFYING
COLOR below). <i>texture</i> is a combination of dashes
‘-’ and dots ‘.’.</p></td></tr>
</table>
<p style="margin-left:11%; margin-top: 1em"><b>SPECIFYING
COLOR</b></p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p style="margin-top: 1em"><i>color</i></p></td>
<td width="4%"></td>
<td width="78%">
<p style="margin-top: 1em">The <i>color</i> of lines, areas
and patterns can be specified by a valid color name; by a
gray shade (in the range 0−255); by a decimal color
code (r/g/b, each in range 0−255; h-s-v, ranges
0−360, 0−1, 0−1; or c/m/y/k, each in range
0−1); or by a hexadecimal color code (#rrggbb, as used
in HTML). See the <b><A HREF="gmtcolors.html">gmtcolors</A></b> manpage for more
information and a full list of color names.</p></td></tr>
</table>
<h2>ASCII FORMAT PRECISION
<a name="ASCII FORMAT PRECISION"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em">The ASCII
output formats of numerical data are controlled by
parameters in your .gmtdefaults4 file. Longitude and
latitude are formatted according to
<b><A HREF="gmtdefaults.html#OUTPUT_DEGREE_FORMAT">OUTPUT_DEGREE_FORMAT</A></b>, whereas other values are
formatted according to <b><A HREF="gmtdefaults.html#D_FORMAT">D_FORMAT</A></b>. Be aware that the
format in effect can lead to loss of precision in the
output, which can lead to various problems downstream. If
you find the output is not written with enough precision,
consider switching to binary output (<b>−bo</b> if
available) or specify more decimals using the
<b><A HREF="gmtdefaults.html#D_FORMAT">D_FORMAT</A></b> setting.</p>
<h2>FILE FORMATS
<a name="FILE FORMATS"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em"><b><A HREF="GMT.html">GMT</A></b> is
able to recognize many of the commonly used grid file
formats, as well as the precision, scale and offset of the
values contained in the grid file. When <b><A HREF="GMT.html">GMT</A></b> needs a
little help with that, you can add the suffix
<b>=</b><i>id</i>[<b>/</b><i>scale</i><b>/</b><i>offset</i>[<b>/</b><i>nan</i>]],
where <i>id</i> is a two-letter identifier of the grid type
and precision, and <i>scale</i> and <i>offset</i> are
optional scale factor and offset to be applied to all grid
values, and <i>nan</i> is the value used to indicate missing
data. See <b><A HREF="grdreformat.html">grdreformat</A></b>(1) and Section 4.17 of the GMT
Technical Reference and Cookbook for more information.</p>
<p style="margin-left:11%; margin-top: 1em">When reading a
netCDF file that contains multiple grids, <b><A HREF="GMT.html">GMT</A></b> will
read, by default, the first 2-dimensional grid that can find
in that file. To coax <b><A HREF="GMT.html">GMT</A></b> into reading another
multi-dimensional variable in the grid file, append
<b>?</b><i>varname</i> to the file name, where
<i>varname</i> is the name of the variable. Note that you
may need to escape the special meaning of <b>?</b> in your
shell program by putting a backslash in front of it, or by
placing the filename and suffix between quotes or double
quotes. See <b><A HREF="grdreformat.html">grdreformat</A></b>(1) and Section 4.18 of the
GMT Technical Reference and Cookbook for more information,
particularly on how to read splices of 3-, 4-, or
5-dimensional grids.</p>
<h2>EXAMPLES
<a name="EXAMPLES"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em">To contour the
file hawaii_grav.grd every 25 mGal on a Mercator map at 0.5
inch/degree, annotate every 50 mGal (using fontsize = 10),
using 1 degree tickmarks, and draw 30 minute gridlines:</p>
<p style="margin-left:11%; margin-top: 1em"><b>grdcontour</b>
hawaii_grav.grd <b>−Jm</b> 0.5<b>i −C</b> 25
<b>−A</b> 50<b>+s</b>10 <b>−B</b>
1<b>g</b>30<b>m</b> > hawaii_grav.ps</p>
<p style="margin-left:11%; margin-top: 1em">To contour the
file image.grd using the levels in the file cont.d on a
linear projection at 0.1 cm/x-unit and 50 cm/y-unit, using
20 (x) and 0.1 (y) tickmarks, smooth the contours a bit, use
"RMS Misfit" as plot-title, use a thick red pen
for annotated contours, and a thin, dashed, blue pen for the
rest, and send the output to the default printer:</p>
<p style="margin-left:11%; margin-top: 1em"><b>grdcontour</b>
image.grd <b>−Jx</b> 0.1<b>c</b>/50.0<b>c −C</b>
cont.d <b>−S</b> 4 <b>−B</b> 20/0.1:."RMS
Misfit": <b>−Wa</b> thick,red <b>−Wc</b>
thinnest,blue,- | lp</p>
<p style="margin-left:11%; margin-top: 1em">The labeling of
local highs and lows may plot outside the innermost contour
since only the mean value of the contour coordinates is used
to position the label.</p>
<h2>SEE ALSO
<a name="SEE ALSO"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em"><i><A HREF="GMT.html">GMT</A></i>(1),
<i><A HREF="gmtdefaults.html">gmtdefaults</A></i>(1), <i><A HREF="gmtcolors.html">gmtcolors</A></i>(5),
<i><A HREF="psbasemap.html">psbasemap</A></i>(1), <i><A HREF="grdimage.html">grdimage</A></i>(1), <i><A HREF="grdview.html">grdview</A></i>(1),
<i><A HREF="pscontour.html">pscontour</A></i>(1)</p>
<hr>
</body>
</html>
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