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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>
<a name="NAME"></a>
<h2>NAME</h2>
<p style="margin-left:11%; margin-top: 1em">grdcontour
− Contouring of 2-D gridded data sets</p>
<a name="SYNOPSIS"></a>
<h2>SYNOPSIS</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>
<a name="DESCRIPTION"></a>
<h2>DESCRIPTION</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 style="margin-top: 1em" valign="top"><b>−C</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">The contours to be
drawn may be specified in one of three possible ways:</p></td>
</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" valign="top"><b>−J</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">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>
</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
IV) <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>
<a name="OPTIONS"></a>
<h2>OPTIONS</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" valign="top"><b>−A</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top"><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>
</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 style="margin-top: 1em" valign="top"><b>+d</b></p></td>
<td width="1%"></td>
<td width="68%">
<p style="margin-top: 1em" valign="top">Turns on debug
which will draw helper points and lines to illustrate the
workings of the quoted line setup.</p></td>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="9%">
<p style="margin-top: 1em" valign="top"><b>+f</b><i>font</i></p> </td>
<td width="1%"></td>
<td width="68%">
<p style="margin-top: 1em" valign="top">Sets the desired
font [Default <b><A HREF="gmtdefaults.html#ANNOT_FONT_PRIMARY">ANNOT_FONT_PRIMARY</A></b>].</p></td>
</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 style="margin-top: 1em" valign="top"><b>+j</b><i>just</i></p> </td>
<td width="1%"></td>
<td width="68%">
<p style="margin-top: 1em" valign="top">Sets label
justification [Default is MC]. Ignored when -SqN|n+|-1 is
used.</p> </td>
</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 style="margin-top: 1em" valign="top"><b>+o</b></p></td>
<td width="7%"></td>
<td width="68%">
<p style="margin-top: 1em" valign="top">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>
</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 style="margin-top: 1em" valign="top"><b>+s</b><i>size</i></p> </td>
<td width="1%"></td>
<td width="68%">
<p style="margin-top: 1em" valign="top">Sets the desired
font size in points [Default is 9].</p></td>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="9%">
<p style="margin-top: 1em" valign="top"><b>+u</b><i>unit</i></p> </td>
<td width="1%"></td>
<td width="68%">
<p style="margin-top: 1em" valign="top">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 no <i>unit</i> is appended we use the units
listed in the grid file. [Default is no unit].</p></td>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="9%">
<p style="margin-top: 1em" valign="top"><b>+v</b></p></td>
<td width="1%"></td>
<td width="68%">
<p style="margin-top: 1em" valign="top">Specifies curved
labels following the path [Default is straight labels].</p></td>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="9%">
<p style="margin-top: 1em" valign="top"><b>+w</b></p></td>
<td width="1%"></td>
<td width="68%">
<p style="margin-top: 1em" valign="top">Specifies how many
(<i>x, y</i>) points will be used to estimate label angles
[Default is 10].</p></td>
</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 style="margin-top: 1em" valign="top"><b>−B</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">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 valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em" valign="top"><b>−D</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">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 valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em" valign="top"><b>−E</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">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 veiw point with
<b>+v</b><i>x0</i>/<i>y0).</i></p> </td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em" valign="top"><b>−F</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">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 valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em" valign="top"><b>−G</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Controls the
placement of labels along the contours. Choose among five
controlling algorithms:</p></td>
</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 style="margin-top: 1em" valign="top"><b>−K</b></p> </td>
<td width="4%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">More
<i>PostScript</i> code will be appended later [Default
terminates the plot system].</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p style="margin-top: 1em" valign="top"><b>−L</b></p> </td>
<td width="4%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Limit range: Do not
draw contours for data values below <i>low</i> or above
<i>high</i>.</p> </td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p style="margin-top: 1em" valign="top"><b>−O</b></p> </td>
<td width="4%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Selects Overlay
plot mode [Default initializes a new plot system].</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p style="margin-top: 1em" valign="top"><b>−P</b></p> </td>
<td width="4%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Selects Portrait
plotting mode [Default is Landscape, see <b><A HREF="gmtdefaults.html">gmtdefaults</A></b>
to change this].</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p style="margin-top: 1em" valign="top"><b>−Q</b></p> </td>
<td width="4%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Do not draw
contours with less than <i>cut</i> number of points [Draw
all contours].</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p style="margin-top: 1em" valign="top"><b>−R</b></p> </td>
<td width="4%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top"><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 valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p style="margin-top: 1em" valign="top"><b>−S</b></p> </td>
<td width="4%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Used to resample
the contour lines at roughly every
(gridbox_size/<i>smoothfactor</i>) interval.</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p style="margin-top: 1em" valign="top"><b>−T</b></p> </td>
<td width="4%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">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 valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p style="margin-top: 1em" valign="top"><b>−U</b></p> </td>
<td width="4%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">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 valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p style="margin-top: 1em" valign="top"><b>−V</b></p> </td>
<td width="4%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Selects verbose
mode, which will send progress reports to stderr [Default
runs "silently"].</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p style="margin-top: 1em" valign="top"><b>−W</b></p> </td>
<td width="4%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top"><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 = 3, color = black, texture =
solid. Regular contours have default width = 1. (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 valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p style="margin-top: 1em" valign="top"><b>−X
−Y</b></p> </td>
<td width="4%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">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 valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p style="margin-top: 1em" valign="top"><b>−Z</b></p> </td>
<td width="4%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">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 this scaling has 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 valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p style="margin-top: 1em" valign="top"><b>−bo</b></p> </td>
<td width="4%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">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 valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p style="margin-top: 1em" valign="top"><b>−c</b></p> </td>
<td width="4%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Specifies the
number of plot copies. [Default is 1].</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p style="margin-top: 1em" valign="top"><b>−f</b></p> </td>
<td width="4%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">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 valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p style="margin-top: 1em" valign="top"><b>−m</b></p> </td>
<td width="4%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">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>
</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 valign="top"><i>pen</i></p></td>
<td width="7%"></td>
<td width="78%">
<p valign="top">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>
</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 valign="top"><i>color</i></p></td>
<td width="4%"></td>
<td width="78%">
<p valign="top">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>
</table>
<a name="ASCII FORMAT PRECISION"></a>
<h2>ASCII FORMAT PRECISION</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>
<a name="FILE FORMATS"></a>
<h2>FILE FORMATS</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>
<a name="EXAMPLES"></a>
<h2>EXAMPLES</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>+f</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>
<a name="SEE ALSO"></a>
<h2>SEE ALSO</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>
