PSMASK(1) Generic Mapping Tools PSMASK(1)NAMEpsmask - To clip or mask areas of no data on a map
SYNOPSISpsmask [xyzfile] -Ixinc[unit][=|+][/yinc[unit][=|+]] -Jparameters
-Rwest/east/south/north[r] [ -B[p|s]parameters ] [ -Ddumpfile ] [
-Eazim/elev[+wlon/lat[/z]][+vx0/y0] ] [ -F ] [ -Gfill ] [ -H[i][nrec] ]
[ -K ] [ -N ] [ -O ] [ -P ] [ -Ssearch_radius[m|c|k|K] ] [ -T ] [
-U[just/dx/dy/][c|label] ] [ -V ] [ -X[a|c|r][x-shift[u]] ] [
-Y[a|c|r][y-shift[u]] ] [ -ccopies ] [ -:[i|o] ] [
-bi[s|S|d|D[ncol]|c[var1/...]] ] [ -m[flag] ]
psmask-C [ -K ] [ -O ]
DESCRIPTIONpsmask 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
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. Optionally,
append a suffix modifier. Geographical (degrees) coordinates:
Append m to indicate arc minutes or c to indicate arc seconds.
If one of the units e, k, i, or n is appended instead, the
increment is assumed to be given in meter, km, miles, or nauti‐
cal miles, respectively, and will be converted to the equivalent
degrees longitude at the middle latitude of the region (the con‐
version depends on 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 coordinates: If = 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 + to the supplied integer argument; the
increment is then recalculated from the number of nodes and the
domain. The resulting increment value depends on whether you
have selected a gridline-registered or pixel-registered grid;
see Appendix B for details. Note: if -Rgrdfile is used then
grid spacing has already been initialized; use -I to override
the values.
-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. When central meridian is optional,
default is center of longitude range on -R option. Default
standard parallel is the equator. For map height, max dimen‐
sion, or min dimension, append h, +, or - to the width, respec‐
tively.
More details can be found in the psbasemap man pages.
CYLINDRICAL PROJECTIONS:
-Jclon0/lat0/scale (Cassini)
-Jcyl_stere/[lon0/[lat0/]]scale (Cylindrical Stereographic)
-Jj[lon0/]scale (Miller)
-Jm[lon0/[lat0/]]scale (Mercator)
-Jmlon0/lat0/scale (Mercator - Give meridian and standard paral‐
lel)
-Jo[a]lon0/lat0/azimuth/scale (Oblique Mercator - point and
azimuth)
-Jo[b]lon0/lat0/lon1/lat1/scale (Oblique Mercator - two points)
-Joclon0/lat0/lonp/latp/scale (Oblique Mercator - point and
pole)
-Jq[lon0/[lat0/]]scale (Cylindrical Equidistant)
-Jtlon0/[lat0/]scale (TM - Transverse Mercator)
-Juzone/scale (UTM - Universal Transverse Mercator)
-Jy[lon0/[lat0/]]scale (Cylindrical Equal-Area)
CONIC PROJECTIONS:
-Jblon0/lat0/lat1/lat2/scale (Albers)
-Jdlon0/lat0/lat1/lat2/scale (Conic Equidistant)
-Jllon0/lat0/lat1/lat2/scale (Lambert Conic Conformal)
-Jpoly/[lon0/[lat0/]]scale ((American) Polyconic)
AZIMUTHAL PROJECTIONS:
-Jalon0/lat0[/horizon]/scale (Lambert Azimuthal Equal-Area)
-Jelon0/lat0[/horizon]/scale (Azimuthal Equidistant)
-Jflon0/lat0[/horizon]/scale (Gnomonic)
-Jglon0/lat0[/horizon]/scale (Orthographic)
-Jglon0/lat0/altitude/azimuth/tilt/twist/Width/Height/scale
(General Perspective).
-Jslon0/lat0[/horizon]/scale (General Stereographic)
MISCELLANEOUS PROJECTIONS:
-Jh[lon0/]scale (Hammer)
-Ji[lon0/]scale (Sinusoidal)
-Jkf[lon0/]scale (Eckert IV)
-Jk[s][lon0/]scale (Eckert VI)
-Jn[lon0/]scale (Robinson)
-Jr[lon0/]scale (Winkel Tripel)
-Jv[lon0/]scale (Van der Grinten)
-Jw[lon0/]scale (Mollweide)
NON-GEOGRAPHICAL PROJECTIONS:
-Jp[a]scale[/origin][r|z] (Polar coordinates (theta,r))
-Jxx-scale[d|l|ppow|t|T][/y-scale[d|l|ppow|t|T]] (Linear, log,
and power scaling)
-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 w/e/s/n.
The two shorthands -Rg and -Rd stand for global domain (0/360
and -180/+180 in longitude respectively, with -90/+90 in lati‐
tude). Alternatively, specify the name of an existing grid file
and the -R settings (and grid spacing, if applicable) are copied
from the grid. For calendar time coordinates you may either
give (a) relative time (relative to the selected TIME_EPOCH and
in the selected TIME_UNIT; append t to -JX|x), or (b) 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 delim‐
iters and their type and positions must be exactly as indicated
(however, input, output and plot formats are customizable; see
gmtdefaults).
OPTIONS
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.
Implicitly sets -O. However, you must supply -Xa and -Ya set‐
tings if you are using absolute positioning.
-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). Append +n<n_pts> to limit the number of
points in files to a minimum of n_pts. That is, do not write
individual polygon files if they do not have at least n_pts ver‐
tices. Often, when one uses the -D option it is not wished to
output any ps code to stdout. In such cases redirect the output
to > /dev/null on *nix systems or to > nul on Windows.
-E Sets the viewpoint's azimuth and elevation (for perspective
view) [180/90]. For frames used for animation, you may want to
append + to fix the center of your data domain (or specify a
particular world coordinate point with +wlon0/lat[/z]) which
will project to the center of your page size (or specify the
coordinates of the projected view point with +vx0/y0).
-F Force pixel node registration [Default is gridline registra‐
tion]. (Node registrations are defined in GMT Cookbook Appendix
B on grid file formats.)
-G Paint the clip polygons (or tiles) with a selected fill [Default
is no fill]. (See SPECIFYING FILL below).
-H Input file(s) has header record(s). If used, the default number
of header records is N_HEADER_RECS. Use -Hi if only input data
should have header records [Default will write out header
records if the input data have them]. Blank lines and lines
starting with # are always skipped. Not used with binary data.
-K More PostScript code will be appended later [Default terminates
the plot system].
-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 [Default is Landscape, see gmtde‐
faults 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 m to
indicate minutes or c to indicate seconds. Append k to indicate
km (implies -R and -I are in degrees, and we will use a fast
flat Earth approximation to calculate distance). For more accu‐
racy, use uppercase K if distances should be calculated along
geodesics. However, if the current ELLIPSOID is spherical then
great circle calculations are used.
-T Plot tiles instead of clip polygons. Use -G to set tile color
or pattern.
-U Draw Unix System time stamp on plot. By adding just/dx/dy/, the
user may specify the justification of the stamp and where the
stamp should fall on the page relative to lower left corner of
the plot. For example, BL/0/0 will align the lower left corner
of the time stamp with the lower left corner of the plot.
Optionally, append a label, or c (which will plot the command
string.). The GMT parameters UNIX_TIME, UNIX_TIME_POS, and
UNIX_TIME_FORMAT can affect the appearance; see the gmtdefaults
man page for details. The time string will be in the locale set
by the environment variable TZ (generally local time).
-V Selects verbose mode, which will send progress reports to stderr
[Default runs "silently"].
-X -Y Shift plot origin relative to the current origin by (x-shift,y-
shift) and optionally append the length unit (c, i, m, p). You
can prepend a to shift the origin back to the original position
after plotting, or prepend r [Default] to reset the current
origin to the new location. If -O is used then the default (x-
shift,y-shift) is (0,0), otherwise it is (r1i, r1i) or (r2.5c,
r2.5c). Alternatively, give c to align the center coordinate (x
or y) of the plot with the center of the page based on 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
affects both].
-bi Selects binary input. Append s for single precision [Default is
d (double)]. Uppercase S or D will force byte-swapping.
Optionally, append ncol, the number of columns in your binary
input file if it exceeds the columns needed by the program. Or
append c if the input file is netCDF. Optionally, append
var1/var2/... to specify the variables to be read. [Default is
2 input columns].
-c Specifies the number of plot copies. [Default is 1].
-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
-b must set the number of output columns explicitly. By default
the -m setting applies to both input and output. Use -mi and
-mo to give separate settings to input and output.
SPECIFYING FILL
fill The attribute fill specifies the solid shade or solid color (see
SPECIFYING COLOR below) or the pattern used for filling poly‐
gons. Patterns are specified as pdpi/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. The dpi sets the resolution
of the image. For 1-bit rasters: use Pdpi/pattern for inverse
video, or append :Fcolor[B[color]] to specify fore- and back‐
ground colors (use color = - for transparency). See GMT Cook‐
book & Technical Reference Appendix E for information on indi‐
vidual patterns.
SPECIFYING COLOR
color The color of lines, areas and patterns can be specified by a
valid color name; by a gray shade (in the range 0-255); by a
decimal color code (r/g/b, each in range 0-255; h-s-v, ranges
0-360, 0-1, 0-1; or c/m/y/k, each in range 0-1); or by a hexa‐
decimal color code (#rrggbb, as used in HTML). See the gmtcol‐
ors manpage for more information and a full list of color names.
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, use:
psmask africa_grav.xyg -R 20/40/20/40 -I 5m -JM 10i -O -K > mask.ps
The same example but this time we use white tiling:
psmask africa_grav.xyg -R 20/40/20/40 -I 5m -JM 10i -T -O -K -G white >
mask.ps
SEE ALSOGMT(1), gmtcolors(5), grdmask(1), surface(1), psbasemap(1), psclip(1)GMT 4.5.14 1 Nov 2015 PSMASK(1)
