NAME
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 ] [ -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 ]
DESCRIPTION
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.
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 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 .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 origin)
-Jmlon0/lat0/scale (Mercator - Give meridian and standard paral-
lel)
-Joalon0/lat0/azimuth/scale (Oblique Mercator - point and
azimuth)
-Joblon0/lat0/lon1/lat1/scale (Oblique Mercator - two points)
-Joclon0/lat0/lonp/latp/scale (Oblique Mercator - point and
pole)
-Jqlon0/scale (Equidistant Cylindrical Projection (Plate Car-
ree))
-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)
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 manpages.
-R west, east, south, and north specify the Region of interest. To
specify boundaries in degrees and minutes [and seconds], use the
dd:mm[:ss] format. Append r if lower left and upper right map
coordinates are given instead of wesn.
OPTIONS
No space between the option flag and the associated arguments
-B Sets map boundary tickmark intervals; see the psbasemap man page
for 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
called mask_*.d).
-E Sets the viewpoint’s azimuth and elevation for perspective plots
[180/90]’
-F Force pixel registration. [Default is grid registration].
-G Paint the clip polygons [or tiles] with selected fill [Default
is no fill].
-G Set fill of positive wiggles. [Default is black] Specify the
shade (0-255) or color (r/g/b), or -Gpdpi/pattern, where pattern
gives the number of the built-in pattern (1-90) OR the name of a
Sun 1-, 8-, or 24-bit raster file. dpi sets the resolution of
the image. For 1-bit rasters: use -GP for inverse video, or
append :Fr/g/b[B[r/g/b]] to specify fore- and background colors
(use r/g/b = - for transparency). See GMT Cookbook & Technical
Reference Appendix E for information on individual patterns.
-H Input file(s) has Header record(s). Number of header records can
be changed by editing your .gmtdefaults 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 character 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 sys-
tem].
-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). 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.
-: Toggles between (longitude,latitude) and (latitude,longitude)
input/output. [Default is (longitude,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 white tiling:
psmask africa_grav.xyg -R20/40/20/40 -I5m -JM10i -T -O -K -G255 >
mask.ps
SEE ALSO
gmt(l), grdmask(l), surface(l), psbasemap(l), psclip(l)
GMT3.4.6 1 Jan 2005 PSMASK(l)
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