psmask - To clip or mask areas of no data on a map
psmask [xyzfile] -Idx[m|c][/dy[m|c]] -Jparameters
-Rwest/east/south/north[r] [ -Btickinfo ] [ -Ddumpfile ] [ -Eaz-
imuth/elevation ] [ -F ] [ -Gfill ] [ -H[nrec] ] [ -K ] [ -M[flag] ] [
-N ] [ -O ] [ -P ] [ -Sradius[k] ] [ -T ] [ -U[/dx/dy/][label] ] [ -V ]
[ -Xx-shift ] [ -Yy-shift ] [ -ccopies ] [ -: ] [ -bi[s][n] ]
psmask -C [ -K ] [ -O ]
psmask reads a (x,y,z) file [or standard input] and uses this informa-
tion to find out which grid cells are reliable. Only gridcells which
have one or more data points are considered reliable. As an option, you
may specify a radius of influence. Then, all gridcells that are within
radius of a data point are considered reliable. Furthermore, an option
is provided to reverse the sense of the test. Having found the reli-
able/not reliable points, psmask will either paint tiles to mask these
nodes (with the -T) switch, or use contouring to create polygons that
will clip out regions of no interest. When clipping is initiated, it
will stay in effect until turned off by a second call to psmask using
the -C option.
File with (x,y,z) values (e.g., that was used to run surface).
If no file is given, standard input is read. For binary files,
-I x_inc [and optionally y_inc] is the grid spacing. Append m to
indicate minutes or c to indicate seconds.
-J 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 MEASURE_UNIT setting in .gmtdefaults4, but this
can be overridden on the command line by appending c, i, or m to
the scale/width value. For map height, max dimension, or min
dimension, append h, +, or - to the width, respectively.
-Jmscale (Mercator - Greenwich and Equator as origin)
-Jmlon0/lat0/scale (Mercator - Give meridian and standard paral-
-Joalon0/lat0/azimuth/scale (Oblique Mercator - point and
-Joblon0/lat0/lon1/lat1/scale (Oblique Mercator - two points)
-Joclon0/lat0/lonp/latp/scale (Oblique Mercator - point and
-Jqlon0/scale (Equidistant Cylindrical Projection (Plate Car-
-Jtlon0/scale (TM - Transverse Mercator, with Equator as y = 0)
-Jtlon0/lat0/scale (TM - Transverse Mercator, set origin)
-Juzone/scale (UTM - Universal Transverse Mercator)
-Jylon0/lats/scale (Basic Cylindrical Projection)
-Jslon0/lat0/[slat/]scale (General Stereographic)
-Jk[f|s]lon0/scale (Eckert IV (f) and VI (s))
-Jrlon0/scale (Winkel Tripel)
-Jvlon0/scale (Van der Grinten)
-Jp[a]scale[/origin] (polar (theta,r) coordinates, optional a
for azimuths and offset theta )
-Jxx-scale[l|ppow][/y-scale[l|ppow]][d] (Linear, log, and power
More details can be found in the psbasemap man pages.
-R xmin, xmax, ymin, and ymax specify the Region of interest. For
geographic regions, these limits correspond to west, east,
south, and north and you may specify them in decimal degrees or
in [+-]dd:mm[:ss.xxx][W|E|S|N] format. Append r if lower left
and upper right map coordinates are given instead of wesn. The
two shorthands -Rg -Rd stand for global domain (0/360 or
-180/+180 in longitude respectively, with -90/+90 in latitude).
For calendar time coordinates you may either give relative time
(relative to the selected TIME_EPOCH and in the selected
TIME_UNIT; append t to -JX|x), or absolute time of the form
[date]T[clock] (append T to -JX|x). At least one of date and
clock must be present; the T is always required. The date string
must be of the form [-]yyyy[-mm[-dd]] (Gregorian calendar) or
yyyy[-Www[-d]] (ISO week calendar), while the clock string must
be of the form hh:mm:ss[.xxx]. The use of delimiters and their
type and positions must be as indicated (however, input/output
and plotting formats are flexible).
No space between the option flag and the associated arguments
-B Sets map boundary annotation and tickmark intervals; see the
psbasemap man page for all the details.
-C Mark end of existing clip path. No input file is needed. Implic-
itly sets -O.
-D Dumps out the resulting clipping polygons to disk. Ignored if -T
is set. If no dumpprefix is given we use mask (Files will be
-E Sets the viewpoint’s azimuth and elevation for perspective plots
-F Force pixel registration. [Default is grid registration].
-G Paint the clip polygons [or tiles] with selected fill [Default
is no fill]. Specify the shade (0-255) or color (r/g/b, each in
0-255, h/s/v, with h in 0-360, s, and v in 0-1, and set
COLOR_MODEL = hsv, or c/m/y/k, each in 0-100 %).
-H Input file(s) has Header record(s). Number of header records can
be changed by editing your .gmtdefaults4 file. If used, GMT
default is 1 header record. Use -Hi if only input data should
have header records [Default will write out header records if
the input data have them]. Not used with binary data.
-K More PostScript code will be appended later [Default terminates
the plot system].
-M Multiple segment file(s). Segments are separated by a special
record. For ASCII files the first character must be flag
[Default is ’>’]. For binary files all fields must be NaN and
-bo[s]n must set the number of output columns explicitly.
-N Invert the sense of the test, i.e. clip regions where there is
-O Selects Overlay plot mode [Default initializes a new plot sys-
-P Selects Portrait plotting mode [GMT Default is Landscape, see
gmtdefaults to change this].
-S Sets radius of influence. Grid nodes within radius of a data
point are considered reliable. [Default is 0, which means that
only grid cells with data in them are reliable]. Append k to
indicate km, also implying that -R and -I are in degrees.
-T Plot tiles instead of clip polygons (Only works with -Jx, -Jj,
-Jm, -Jq, and -Jy). Use -G to set tile color.
-U Draw Unix System time stamp on plot. User may specify where the
lower left corner of the stamp should fall on the page relative
to lower left corner of plot. Optionally, append a label, or c
(which will plot the command string.). The GMT parameters
UNIX_TIME and UNIX_TIME_POS can affect the appearance; see the
gmtdefaults man page for details.
-V Selects verbose mode, which will send progress reports to stderr
[Default runs "silently"].
-X -Y Shift origin of plot by (x-shift,y-shift). Prepend a for abso-
lute coordinates; the default (r) will reset plot origin. Give
c to center plot using current page size.
-: Toggles between (longitude,latitude) and (latitude,longitude)
input and/or output. [Default is (longitude,latitude)]. Append
i to select input only or o to select output only. [Default
-bi Selects binary input. Append s for single precision [Default is
double]. Append n for the number of columns in the binary
[Default is 2 input columns].
-c Specifies the number of plot copies. [Default is 1].
To make an overlay PostScript file that will mask out the regions of a
contour map where there is no control data using clip polygons, use:
psmask africa_grav.xyg -R20/40/20/40 -I5m -JM10i -O -K > mask.ps
The same example but this time we use white tiling:
psmask africa_grav.xyg -R20/40/20/40 -I5m -JM10i -T -O -K -G255 >
gmt(l), grdmask(l), surface(l), psbasemap(l), psclip(l)
GMT4.0 1 Oct 2004 PSMASK(l)
Man(1) output converted with