NAME
psclip - To set up polygonal clip paths
SYNOPSIS
psclip xyfiles -Jparameters -Rwest/east/south/north[r] [ -Btickinfo ] [
-Eaz/el ] [ -K ] [ -N ] [ -M[flag] ] [ -O ] [ -P ] [ -U[/dx/dy/][label]
] [ -V ] [ -Xx-shift ] [ -Yy-shift ] [ -Zzlevel ] [ -ccopies ] [ -: ] [
-bi[s][n] ] [ -f[i|o]colinfo ]
psclip -C [ -K ] [ -O ]
DESCRIPTION
psclip reads (x,y) file(s) [or standard input] and draws polygons that
are activated as clipping paths. Several files may be read to create
complex paths consisting of several non-connecting segments. As an
option (-N), the user may choose to reverse the sense of what is the
inside and outside of the paths. After subsequent plotting, which will
be clipped against these paths, the clipping may be deactivated by run-
ning psclip a second time with the -C option only.
xyfiles
ASCII [or binary, see -b] file(s) with (x,y) values for clip
polygons. If no files are given, the standard input is read.
-C Mark end of existing clip path. No input file or projection
information are needed.
-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. For map height, max dimension, or min
dimension, append h, +, or - to the width, respectively.
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]][d] (Linear, log, and power
scaling)
More details can be found in the psbasemap man pages.
-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 wesn. The
two shorthands -Rg -Rd stand for global domain (0/360 or
-180/+180 in longitude respectively, with -90/+90 in latitude).
For calendar time coordinates you may either give relative time
(relative to the selected TIME_EPOCH and in the selected
TIME_UNIT; append t to -JX|x), or 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 as indicated (however, input/output
and plotting formats are flexible).
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.
-E Sets the viewpoint’s azimuth and elevation [180/90].
-H Input file(s) has Header record(s). Number of header records can
be changed by editing your .gmtdefaults4 file. If used, GMT
default is 1 header record. Use -Hi if only input data should
have header records [Default will write out header records if
the input data have them].
-K More PostScript code will be appended later [Default terminates
the plot system].
-M Multiple segment file. Segments are separated by a record whose
first character is <flag>. [Default is ’>’].
-N Invert the sense of what is inside and outside, i.e., use the
outside of the polygons for clipping.
-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].
-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. Give
c to center plot using current page size.
-Z For 3-D projections: Sets the z-level of the polygons [0].
-: 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].
-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].
-f Special formatting of input and output columns (time or geo-
graphical data) Specify i(nput) or o(utput) [Default is both
input and output]. Give one or more columns (or column ranges)
separated by commas. Append T (Absolute calendar time), t (time
relative to chosen TIME_EPOCH), x (longitude), y (latitude), g
(geographic coordinate), or f (floating point) to each column or
column range item.
EXAMPLES
To make an overlay PostScript file that will set up a complex clip area
to which subsequent plotting will be confined, run:
psclip my_region.xy -R0/40/0/40 -Jm0.3i -O -K > clip_mask_on.ps
To deactivate the clipping in an existing plotfile, run:
psclip -C -O >> complex_plot.ps
BUGS
psclip cannot handle polygons that contain the south or north pole. For
such polygons, you should split them into two and make each explicitly
contain the polar point. The two clip polygons will combine to give the
desired effect.
SEE ALSO
gmt(l), grdmask(l), psbasemap(l), psmask(l)
GMT4.0 1 Oct 2004 PSCLIP(l)
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