psmask
psmask - To clip or mask areas of no data on a map
SYNOPSIS
psmask [xyzfile] -Idx[m|c][/dy[m|c]] -Jparameters
-Rwest/east/south/north[r] [ -Btickinfo ] [ -Ddumpfile ] [
-Eazimuth/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 ]
DESCRIPTION
psmask reads a (x,y,z) file [or standard input] and uses
this information to find out which grid cells are reli
able. 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. Further
more, an option is provided to reverse the sense of the
test. Having found the reliable/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.
xyzfile
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, see -b.
-I x_inc [and optionally y_inc] is the grid spacing.
Append m to indicate minutes or c to indicate sec
onds.
-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 MEA
SURE_UNIT setting in .gmtdefaults, but this can be
overridden on the command line by appending the c,
i, or m to the scale/width value.
CYLINDRICAL PROJECTIONS:
-Jclon0/lat0/scale (Cassini)
-Jjlon0/scale (Miller)
-Jmscale (Mercator - Greenwich and Equator as ori
gin)
-Jmlon0/lat0/scale (Mercator - Give meridian and
standard parallel)
-Joalon0/lat0/azimuth/scale (Oblique Mercator -
two points)
-Joclon0/lat0/lonp/latp/scale (Oblique Mercator -
point and pole)
-Jqlon0/scale (Equidistant Cylindrical Projection
(Plate Carree))
-Jtlon0/scale (TM - Transverse Mercator, with Equa
tor as y = 0)
-Jtlon0/lat0/scale (TM - Transverse Mercator, set
origin)
-Juzone/scale (UTM - Universal Transverse Mercator)
-Jylon0/lats/scale (Basic Cylindrical Projection)
AZIMUTHAL PROJECTIONS:
-Jalon0/lat0/scale (Lambert).
-Jelon0/lat0/scale (Equidistant).
-Jflon0/lat0/horizon/scale (Gnomonic).
-Jglon0/lat0/scale (Orthographic).
-Jslon0/lat0/[slat/]scale (General Stereographic)
CONIC PROJECTIONS:
-Jblon0/lat0/lat1/lat2/scale (Albers)
-Jdlon0/lat0/lat1/lat2/scale (Equidistant)
-Jllon0/lat0/lat1/lat2/scale (Lambert)
MISCELLANEOUS PROJECTIONS:
-Jhlon0/scale (Hammer)
-Jilon0/scale (Sinusoidal)
-Jk[f|s]lon0/scale (Eckert IV (f) and VI (s))
-Jnlon0/scale (Robinson)
-Jrlon0/scale (Winkel Tripel)
-Jvlon0/scale (Van der Grinten)
-Jwlon0/scale (Mollweide)
NON-GEOGRAPHICAL PROJECTIONS:
-Jp[a]scale[/origin] (polar (theta,r) coordinates,
optional a for azimuths and offset theta [0])
-Jxx-scale[l|ppow][/y-scale[l|ppow]] (Linear, log,
and power scaling)
More details can be found in the psbasemap man
pages.
-R west, east, south, and north specify the Region of
interest. To specify boundaries in degrees and min
utes [and seconds], use the dd:mm[:ss] format.
Append r if lower left and upper right map coordi
nates are given instead of wesn.
OPTIONS
-B Sets map boundary tickmark intervals. See psbasemap
for details.
-C Mark end of existing clip path. No input file is
needed. Implicitly 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 called mask_*.d).
-E Sets the viewpoint's azimuth and elevation for per
spective plots [180/90]'
-F Force pixel registration. [Default is grid regis
tration].
-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 Input file(s) has Header record(s). Number of
header records can be changed by editing your .gmt
defaults file. If used, GMT default is 1 header
record. 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 char
acter must be flag [Default is '>']. For binary
files all fields must be NaN.
-N Invert the sense of the test, i.e. clip regions
where there is data coverage.
-O Selects Overlay plot mode [Default initializes a
new plot system].
-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 indicated km, also
implying that -R -I are in degrees.
-T Plot tiles instead of clip polygons (Only works
with -Jx, -Jj, -Jm, -Jq, and -Jy).
ify 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 appear
ance; 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 absolute coordinates; the default (r) will
reset plot origin.
-: Toggles between (longitude,latitude) and (lati
tude,longitude) input/output. [Default is (longi
tude,latitude)]. Applies to geographic coordinates
only.
-c Specifies the number of plot copies. [Default is 1]
-bi Selects binary input. Append s for single precision
[Default is double]. Append n for the number of
columns in the binary file(s). [Default is 2 input
columns].
EXAMPLES
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, try:
psmask africa_grav.xyg -R20/40/20/40 -I5m -JM10i -O -K >
mask.ps
The same example but this time we use tiling:
psmask africa_grav.xyg -R20/40/20/40 -I5m -JM10i -T -O -K
> mask.ps
SEE ALSO
gmt(l), grdmask(l), surface(l), psbasemap(l), psclip(l)
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