pscontour(1gmt)
NAME
pscontour - Contour table data by direct triangulation [method]
SYNOPSIS
pscontour [ table ] -C[+]cpt -Jparameters
-Rwest/east/south/north[/zmin/zmax][r] [
-A[-|[+]annot_int][labelinfo] ] [ -B[p|s]parameters ] [ -D[template]
] [ -Eindexfile ] [ -G[d|f|n|l|L|x|X]params ] [ -I ] [
-Jz|Zparameters ] [ -K ] [ -Lpen ] [ -N ] [ -O ] [ -P ] [ -Qcut ]
[ -S[p|t] ] [ -T[+|-][+dgap[/length]][+l[labels]] ] [ -U[stamp] ] [
-V[level] ] [ -W[type]pen ][+c[l|f]] [ -Xx_offset ] [ -Yy_offset ] [
-bbinary ] [ -ccopies ] [ -hheaders ] [ -iflags ] [ -pflags ] [
-ttransp ] [ -:[i|o] ]
Note: No space is allowed between the option flag and the associated
arguments.
DESCRIPTION
pscontour reads an ASCII [or binary] table and produces a raw contour plot by triangulation. By default, the optimal Delaunay triangulation is performed (using either Shewchuk's [1996] or Watson's [1982] method as selected during GMT installation; type pscontour - to see which method is selected), but the user may optionally provide a second file with network information, such as a triangular mesh used for finite element modeling. In addition to contours, the area between contours may be painted according to the CPT. Alternatively, the x/y/z positions of the contour lines may be saved to one or more output files (or stdout) and no plot is produced.
REQUIRED ARGUMENTS
-C[+]cont_int
The contours to be drawn may be specified in one of three
possible ways:
1. If cont_int has the suffix ".cpt" and can be opened as a
file, it is assumed to be a CPT. The color boundaries are
then used as contour levels. If the CPT has annotation flags
in the last column then those contours will be annotated. By
default all contours are labeled; use -A- to disable all
annotations.
2. If cont_int is a file but not a CPT, 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.
3. If no file is found, then cont_int is interpreted as a
constant contour interval. However, if prepended with the +
sign the cont_int is taken as meaning draw that single
contour. The -A option offers the same possibility so they
may be used together to plot only one annotated and one
non-annotated contour. If -A is set and -C is not, then the
contour interval is set equal to the specified annotation
interval.
If a file is given and -T is set, then only contours marked with
upper case C or A will have tick-marks. In all cases the contour
values have the same units as the file.
-Jparameters (more ...)
Select map projection.
-R[unit]xmin/xmax/ymin/ymax[r] (more ...)
Specify the region of interest.
For perspective view p, optionally append /zmin/zmax. (more ...)
OPTIONAL ARGUMENTS
table One or more ASCII (or binary, see -bi[ncols][type]) data table
file(s) holding a number of data columns. If no tables are given
then we read from standard input.
-A[-|[+]annot_int][labelinfo]
annot_int is annotation interval in data units; it is ignored if
contour levels are given in a file. [Default is no annotations].
Append - to disable all annotations implied by -C. Alternatively
prepend + to the annotation interval to plot that as a single
contour. The optional labelinfo controls the specifics of the
label formatting and consists of a concatenated string made up
of any of the following control arguments:
+aangle
For annotations at a fixed angle, +an for contour-normal, or
+ap for contour-parallel [Default]. For +ap, you may
optionally append u for up-hill and d for down-hill
cartographic annotations.
+cdx[/dy]
Sets the clearance between label and optional text box.
Append c|i|p to specify the unit or % to indicate a
percentage of the label font size [15%].
+d Turns on debug which will draw helper points and lines to
illustrate the workings of the contour line setup.
+e Delay the plotting of the text. This is used to build a clip
path based on the text, then lay down other overlays while
that clip path is in effect, then turning of clipping with
psclip -Cs which finally plots the original text.
+ffont Sets the desired font [Default FONT_ANNOT_PRIMARY with its
size changed to 9p].
+g[color]
Selects opaque text boxes [Default is transparent];
optionally specify the color [Default is PS_PAGE_COLOR].
+jjust Sets label justification [Default is MC].
+ndx[/dy]
Nudges the placement of labels by the specified amount
(append c|i|p to specify the units). Increments are
considered in the coordinate system defined by the
orientation of the contour; use +N to force increments in the
plot x/y coordinates system [no nudging]. Not allowed with
+v.
+o Selects rounded rectangular text box [Default is
rectangular]. Not applicable for curved text (+v) and only
makes sense for opaque text boxes.
+p[pen]
Draws the outline of text boxes [Default is no outline];
optionally specify pen for outline [Default is width = 0.25p,
color = black, style = solid].
+rmin_rad
Will not place labels where the contours's radius of
curvature is less than min_rad [Default is 0].
+t[file]
Saves contour label x, y, angle, and text to file
[Contour_labels.txt].
+uunit Appends unit to all contour labels. [Default is no unit]. If
z is appended we use the z-unit from the grdfile.
+v Specifies curved labels following the contour [Default is
straight labels].
+w Specifies how many (x,y) points will be used to estimate
label angles [automatic].
+=prefix
Prepends prefix to all contour labels. [Default is no
prefix].
-B[p|s]parameters (more ...)
Set map boundary intervals.
-D[template]
Dump the (x,y,z) coordinates of each contour to one or more output
files (or stdout if template is not given). No plotting will take
place. If template contains one or more of the C-format specifiers
%d, %f, %c then line segments will be written to different files;
otherwise all lines are written to the specified file (template).
The use of the C-format specifiers controls how many files are
created and how the contours are organized. If the float format %f
is present (standard modifications to width and precision are
allowed, e.g., %f7.3f), then the filenames will contain the contour
value and lines are thus separated into files based on a common
contour value. If the integer format %d is present (including
modifications like %05d), then all contours are written to
individual segment files; if any of the other specifiers are present
they just affect the file names. Finally, if the character format %c
is present it is replaced with the letters C (for closed) or O (for
open), reflecting the nature of each contour. Any combination of
one, two, or all three modifiers are valid, resulting in different
filenames and number of files. For instance, if %c appears by
itself, then only two files are created, separating the open from
the closed contours (assuming both kinds are present). If just %f is
used, then all segments for the same contour level will be written
to the same file, resulting in N multi-segment files. If both %f and
%c were combined then each contour level would be further subdivided
into closed and open contours. Any combination involving %d will
result in one individual file for each segment; %c, %f only modifies
the file names. The files are ASCII unless -bo is used.
-Eindexfile
Give name of file with network information. Each record must
contain triplets of node numbers for a triangle [Default
computes these using Delaunay triangulation (see triangulate)].
-G
The required argument controls the placement of labels along the
quoted lines. Choose among five controlling algorithms:
ddist[c|i|p] or Ddist[d|e|f|k|m|M|n|s]
For lower case d, give distances between labels on the plot
in your preferred measurement unit c (cm), i (inch), or p
(points), while for upper case D, specify distances in map
units and append the unit; choose among e (m), f (foot), k
(km), M (mile), n (nautical mile) or u (US survey foot), and
d (arc degree), m (arc minute), or s (arc second). [Default
is 10c or 4i]. As an option, you can append /fraction which
is used to place the very first label for each contour when
the cumulative along-contour distance equals fraction * dist
[0.25].
fffile.d
Reads the ASCII file ffile.d and places labels at locations
in the file that matches locations along the quoted lines.
Inexact matches and points outside the region are skipped.
l|Lline1[,line2,...]
Give start and stop coordinates for one or more
comma-separated straight line segments. Labels will be placed
where these lines intersect the quoted lines. The format of
each line specification is start/stop, where start and stop
are either a specified point lon/lat or a 2-character XY key
that uses the justification format employed in pstext to
indicate a point on the map, given as [LCR][BMT]. In
addition, you can use Z-, Z+ to mean the global minimum and
maximum locations in the grid. L will interpret the point
pairs as defining great circles [Default is straight line].
nn_label
Specifies the number of equidistant labels for quoted lines
line [1]. Upper case N starts labeling exactly at the start
of the line [Default centers them along the line]. N-1 places
one justified label at start, while N+1 places one justified
label at the end of quoted lines. Optionally, append
/min_dist[c|i|p] to enforce that a minimum distance
separation between successive labels is enforced.
x|Xxfile.d
Reads the multisegment file xfile.d and places labels at the
intersections between the quoted lines and the lines in
xfile.d. X will resample the lines first along great-circle
arcs.
In addition, you may optionally append +rradius[c|i|p] to set a
minimum label separation in the x-y plane [no limitation].
-I Color the triangles using the CPT.
-Jz|Zparameters (more ...)
Set z-axis scaling; same syntax as -Jx.
-K (more ...)
Do not finalize the PostScript plot.
-Lpen (more ...)
Draw the underlying triangular mesh using the specified pen
attributes [Default is no mesh].
-N Do NOT clip contours or image at the boundaries [Default will
clip to fit inside region -R].
-O (more ...)
Append to existing PostScript plot.
-P (more ...)
Select "Portrait" plot orientation.
-Qcut Do not draw contours with less than cut number of points [Draw
all contours].
-S[p|t]
Skip all input xyz points that fall outside the region [Default
uses all the data in the triangulation]. Alternatively, use -St
to skip triangles whose three vertices are all outside the
region. -S with no modifier is interpreted as -Sp.
-T[+|-][+dgap[/length]][+l[labels]]
Will draw tick marks pointing in the downward direction every
gap along the innermost closed contours. Append +dgap and
optionally tick mark length (append units as c, i, or p) or use
defaults [15p/3p]. User may choose to tick only local highs or
local lows by specifying -T+ or -T-, respectively. Append
+llabels to annotate the centers of closed innermost contours
(i.e., the local lows and highs). If no labels is appended we
use - and + as the labels. Appending exactly two characters,
e.g., +lLH, will plot the two characters (here, L and H) as
labels. For more elaborate labels, separate the low and hight
label strings with a comma (e.g., +llo,hi). If a file is given
by -C and -T is set, then only contours marked with upper case C
or A will have tick marks [and annotations].
-U[just/dx/dy/][c|label] (more ...)
Draw GMT time stamp logo on plot.
-V[level] (more ...)
Select verbosity level [c].
-W[type]pen[+c[l|f]] (more ...)
type, if present, can be a for annotated contours or c for
regular contours [Default]. The pen sets the attributes for the
particular line. Default pen for annotated contours:
0.75p,black. Regular contours use pen 0.25p,black. If the
modifier +cl is appended then the color of the contour lines are
taken from the CPT (see -C). If instead modifier +cf is appended
then the color from the cpt file is applied to the contour
annotations. Use just +c for both effects.
-X[a|c|f|r][x-shift[u]]
-Y[a|c|f|r][y-shift[u]] (more ...)
Shift plot origin.
-bi[ncols][t] (more ...)
Select native binary input. [Default is 3 input columns]. Use
4-byte integer triplets for node ids (-E).
-bo[ncols][type] (more ...)
Select native binary output. [Default is 3 output columns].
-ccopies (more ...)
Specify number of plot copies [Default is 1].
-h[i|o][n][+c][+d][+rremark][+rtitle] (more ...)
Skip or produce header record(s).
-icols[l][sscale][ooffset][,...] (more ...)
Select input columns (0 is first column).
-:[i|o] (more ...)
Swap 1st and 2nd column on input and/or output.
-p[x|y|z]azim/elev[/zlevel][+wlon0/lat0[/z0]][+vx0/y0] (more ...)
Select perspective view.
-t[transp] (more ...)
Set PDF transparency level in percent.
-^ or just -
Print a short message about the syntax of the command, then
exits (NOTE: on Windows use just -).
-+ or just +
Print an extensive usage (help) message, including the
explanation of any module-specific option (but not the GMT
common options), then exits.
-? or no arguments
Print a complete usage (help) message, including the explanation
of options, then exits.
EXAMPLES
To make a raw contour plot from the file topo.xyz and drawing the
contours (pen = 2) given in the CPT topo.cpt on a Lambert map at 0.5
inch/degree along the standard parallels 18 and 24, use
gmt pscontour topo.xyz -R320/330/20/30 -Jl18/24/0.5i -Ctopo.cpt -W0.5p > topo.ps
To create a color PostScript plot of the numerical temperature solution
obtained on a triangular mesh whose node coordinates and temperatures
are stored in temp.xyz and mesh arrangement is given by the file
mesh.ijk, using the colors in temp.cpt, run
gmt pscontour temp.xyz -R0/150/0/100 -Jx0.1i -Ctemp.cpt -G -W0.25p > temp.ps
To save the triangulated 100-m contour lines in topo.txt and separate
them into multisegment files (one for each contour level), try
gmt pscontour topo.txt -C100 -Dcontours_%.0f.txt
SEE ALSO
gmt, gmt.conf, gmtcolors, grdcontour, grdimage, nearneighbor, psbasemap, psscale, surface, triangulate
REFERENCES
Watson, D. F., 1982, Acord: Automatic contouring of raw data, Comp. & Geosci., 8, 97-101. Shewchuk, J. R., 1996, Triangle: Engineering a 2D Quality Mesh Generator and Delaunay Triangulator, First Workshop on Applied Computational Geometry (Philadelphia, PA), 124-133, ACM, May 1996. http://www.cs.cmu.edu/~quake/triangle.html
COPYRIGHT
2016, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe
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