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psmask(1)                             GMT                            psmask(1)


       psmask - Use data tables to clip or mask map areas with no coverage


       psmask [ table ]
        -Rregion [  -B[p|s]parameters ] [  -Ddumpfile ] [  -F[l|r] ] [  -Gfill
       ] [  -Jz|Zparameters ] [  -K ] [  -L[+|-]nodegrid ] [  -N ] [  -O  ]  [
       -P  ]  [   -Qcut  ] [  -Ssearch_radius[unit] ] [  -T ] [  -U[stamp] ] [
       -V[level] ] [  -Xx_offset ] [  -Yy_offset ] [ -bibinary ] [ -dinodata ]
       [  -eregexp ] [ -hheaders ] [ -iflags ] [ -pflags ] [ -r ] [ -ttransp ]
       [ -:[i|o] ]

       psmask -C [ -K ] [ -O ]

       Note: No space is allowed between the option flag  and  the  associated


       psmask  reads a (x,y,z) file [or standard input] and uses this informa-
       tion to find out which grid cells are reliable. Only grid  cells  which
       have one or more data points are considered reliable. As an option, you
       may specify a radius of influence. Then, all grid cells 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.


              x_inc  [and  optionally  y_inc] is the grid spacing. Optionally,
              append a suffix modifier.  Geographical  (degrees)  coordinates:
              Append  m  to indicate arc minutes or s to indicate arc seconds.
              If one of the units e, f, k, M, n or u is appended instead,  the
              increment  is assumed to be given in meter, foot, km, Mile, nau-
              tical mile or US survey foot, respectively,  and  will  be  con-
              verted  to  the equivalent degrees longitude at the middle lati-
              tude of the region (the conversion depends  on  PROJ_ELLIPSOID).
              If  y_inc is given but set to 0 it will be reset equal to x_inc;
              otherwise it will be converted to degrees latitude. All  coordi-
              nates:  If +e is appended then the corresponding max x (east) or
              y (north) may be slightly adjusted  to  fit  exactly  the  given
              increment  [by default the increment may be adjusted slightly to
              fit the given domain]. Finally, instead of giving  an  increment
              you  may  specify the number of nodes desired by appending +n to
              the supplied integer argument; the increment  is  then  recalcu-
              lated  from  the  number  of nodes and the domain. The resulting
              increment value depends on whether you  have  selected  a  grid-
              line-registered  or  pixel-registered grid; see App-file-formats
              for details. Note: if -Rgrdfile is used then  the  grid  spacing
              has already been initialized; use -I to override the values.

       -Jparameters (more a|)
              Select map projection. [Not mandatory when -D].

       -Rxmin/xmax/ymin/ymax[+r][+uunit] (more a|)
              Specify the region of interest.

       For perspective view p, optionally append /zmin/zmax. (more a|)


       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.

       -B[p|s]parameters (more a|)
              Set map boundary frame and axes attributes.

       -C     Mark end of existing clip path. No input file is needed. Implic-
              itly sets -O. Also supply -X and -Y settings if you  have  moved
              since the clip started.

              Dump  the  (x,y)  coordinates of each clipping polygon to one or
              more output files (or stdout if template is not given). No plot-
              ting  will  take place. If template contains the C-format speci-
              fier %d (including modifications like %05d) then  polygons  will
              be  written to different files; otherwise all polygons are writ-
              ten to the specified file (template). The files are ASCII unless
              -bo  is  used.  See -Q to exclude small polygons from considera-

              Force clip contours (polygons)  to  be  oriented  so  that  data
              points are to the left (-Fl [Default]) or right (-Fr) as we move
              along the perimeter [Default is arbitrary orientation]. Requires

       -Gfill Paint the clip polygons (or tiles) with a selected fill [Default
              is no fill].

       -Jz|Zparameters (more a|)
              Set z-axis scaling; same syntax as -Jx.

       -K (more a|)
              Do not finalize the PostScript plot.

              Save the internal grid with ones (data constraint) and zeros (no
              data)  to the named nodegrid [no grid saved].  Use L+ to convert
              the no data flags to NaNs before writing the grid, while L- will
              instead convert the data flags to NaNs.

       -N     Invert  the sense of the test, i.e., clip regions where there is
              data coverage.

       -O (more a|)
              Append to existing PostScript plot.

       -P (more a|)
              Select aPortraita plot orientation.

       -Q     Do not dump polygons with less than cut number of points  [Dumps
              all polygons]. Only applicable if -D has been specified.

              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 the dis-
              tance unit (see UNITS).

       -T     Plot tiles instead of clip polygons. Use -G to set tile color or
              pattern. Cannot be used with -D.

       -U[[just]/dx/dy/][c|label] (more a|)
              Draw GMT time stamp logo on plot.

       -V[level] (more a|)
              Select verbosity level [c].


       -Y[a|c|f|r][y-shift[u]] (more a|)
              Shift plot origin.

       -bi[ncols][t] (more a|)
              Select native binary input. [Default is 2 input columns].

       -dinodata (more a|)
              Replace input columns that equal nodata with NaN.

       -e[~]^<i>apattern^<i>a | -e[~]/regexp/[i] (more a|)
              Only accept data records that match the given pattern.

       -h[i|o][n][+c][+d][+rremark][+rtitle] (more a|)
              Skip or produce header record(s). Not used with binary data.

       -icols[+l][+sscale][+ooffset][,^<i>a|] (more a|)
              Select input columns and transformations (0 is first column).

       -p[x|y|z]azim[/elev[/zlevel]][+wlon0/lat0[/z0]][+vx0/y0] (more a|)
              Select perspective view.

       -r (more a|)
              Set pixel node registration [gridline].

       -t[transp] (more a|)
              Set PDF transparency level in percent.

       -:[i|o] (more a|)
              Swap 1st and 2nd column on input and/or output.

       -^ or just -
              Print  a  short  message  about  the syntax of the command, then
              exits (NOTE: on Windows just use -).

       -+ or just +
              Print an extensive usage (help) message, including the  explana-
              tion  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 all options, then exits.


       For  map distance unit, append unit d for arc degree, m for arc minute,
       and s for arc second, or e for meter [Default], f for foot, k for km, M
       for  statute  mile,  n  for nautical mile, and u for US survey foot. By
       default we compute such distances using a spherical approximation  with
       great  circles.  Prepend - to a distance (or the unit is no distance is
       given) to perform aFlat Eartha calculations (quicker but less accurate)
       or  prepend  +  to perform exact geodesic calculations (slower but more


       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:

              gmt psmask africa_grav.xyg -R20/40/20/40 -I5m -JM10i -O -K >

       We  do it again, but this time we wish to save the clipping polygons to
       file all_pols.txt:

              gmt psmask africa_grav.xyg -R20/40/20/40 -I5m -Dall_pols.txt

       A repeat of the first example but this time we use white tiling:

              gmt psmask africa_grav.xyg -R20/40/20/40 -I5m -JM10i -T -O -K -Gwhite >


       gmt(1), gmtcolors(5), grdmask(1), surface(1), psbasemap(1), psclip(1)


       2017, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe

5.4.2                            Jun 24, 2017                        psmask(1)

gmt5 5.4.2 - Generated Thu Jun 29 15:31:41 CDT 2017
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