DragonFly On-Line Manual Pages
PSMASK(1) Generic Mapping Tools PSMASK(1)
NAME
psmask - To clip or mask areas of no data on a map
SYNOPSIS
psmask [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 ]
DESCRIPTION
psmask reads a (x,y,z) file [or standard input] and uses this
information 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
nautical miles, respectively, and will be converted to the
equivalent degrees longitude at the middle latitude of the
region (the conversion 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
dimension, or min dimension, append h, *, or - to the width,
respectively.
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
parallel)
-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
latitude). 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 delimiters 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
settings 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
vertices. 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
registration]. (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
system].
-P Selects Portrait plotting mode [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 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
accuracy, 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
polygons. 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
background colors (use color = - for transparency). See GMT
Cookbook & Technical Reference Appendix E for information on
individual 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
hexadecimal color code (#rrggbb, as used in HTML). See the
gmtcolors 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 ALSO
GMT(1), gmtcolors(5), grdmask(1), surface(1), psbasemap(1), psclip(1)
GMT 4.5.14 1 Nov 2015 PSMASK(1)