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 ] [
-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 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. 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
parallel)
-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
Carree))
-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 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 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]. 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 .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.
- -bo
- Selects binary output. Append s for single precision
[Default is double].
- -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).
- -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 absolute 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
-I5
m -JM10
i
-O -K > mask.ps
The same example but this time we use tiling:
psmask africa_grav.xyg
-R20/40/20/40
-I5
m -JM10
i
-T -O -K > mask.ps
SEE ALSO¶
gmt(1gmt),
grdmask(1gmt),
surface(1gmt),
psbasemap(1gmt),
psclip(1gmt)