grdimage - Create grayshaded or colored image from a 2-D netCDF grd
grdimage grdfile -Ccptfile -Jparameters [ -Btickinfo ] [ -Edpi ] [
-Iintensfile] [ -K ] [ -M ] [ -O ] [ -P ] [ -Rwest/east/south/north[r]
] [ -U[/dx/dy/][label] ] [ -V ] [ -Xx-shift ] [ -Yy-shift ] [ -ccopies
grdimage reads a 2-D gridded file and produces a gray-shaded (or
colored) map by assigning each contour interval a gray-shade (or
color). Optionally, illumination may be added by providing a file
with intensities in the (-1,+1) range. Values outside this range will
be clipped. Such intensity files can be created from the grdfile
using grdgradient and modified by grdmath or grdhisteq. Each grid-
node in the grdfile is represented as a shaded (or colored) rectangle
centered on the grid node. When using map projections, the grid is
first resampled on a new rectangular grid (This can be a time-
consuming process for large grid files). A 24-bit true color
PostScript file is output. The region option can be used to select a
map region larger or smaller than that implied by the extent of the
2-D gridded data set to be imaged
-C name of the color palette table
-J Selects the map projection. Scale is inch/degree, 1:xxxxx, or
width in inch (upper case modifier).
-Jmscale (Mercator - Greenwich and Equator as origin)
-Jmlon0/lat0/scale (Mercator - Give meridian and standard
-Joalon0/lat0/azimuth/scale (Oblique Mercator - point and
-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)
-Juzone/scale (UTM - Universal Transverse Mercator)
-Jylon0/lats/scale (Basic Cylindrical Projection)
-Jslon0/lat0/scale (General Stereographic)
-Jklon0/scale (Eckert VI)
-Jrlon0/scale (Winkel Tripel)
-Jpscale (Linear projection for polar (theta,r) coordinates)
-Jxx-scale[l|ppow][/y-scale[l|ppow]] (Linear, log, and power
More details can be found in the psbasemap manpages.
No space between the option flag and the associated arguments.
-B Sets map boundary tickmark intervals. See psbasemap for details.
-E Sets the resolution of the projected grid that will be created if
a map projection other than Linear or Mercator was selected. By
default, the projected grid will be of the same size (rows and
columns) as the input file.
-I Gives the name of a grdfile with intensities in the (-1,+1)
range. [Default is no illumination].
-K More PostScript code will be appended later [Default terminates
the plot system].
-M Force conversion to monochrome image using the (television) YIQ
-O Selects Overlay plot mode [Default initializes a new plot
-P Selects Portrait plotting mode [GMT Default is Landscape, see
gmtdefaults to change this].
-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. You may ask for a larger
w/e/s/n region to have more room between the image and the axes.
A smaller region than specified in the grdfile will result in a
subset of the grid [Default is region given by the grdfile].
-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 in inch [Default is (-0.75i/-
0.75i)]. Optionally, append a label, or c (which will plot the
-V Selects verbose mode, which will send progress reports to stderr
[Default runs "silently"].
Shift origin of plot by (x-shift,y-shift) inch [Default is
(a1i,a1i) for new plots, (0,0) for overlays]. Prepend a for
absolute coordinates; the default (r) will reset plot origin.
-c Specifies the number of plot copies. [Default is 1]
To gray-shade the file hawaii_grav.grd with shades given in shades.cpt
on a Lambert map at 0.5 inch/degree along the standard parallels 18
and 24, and using 1 degree tickmarks, try
grdimage hawaii_grav.grd -Jl18/24/0.5i -Cshades.cpt -B1 >
To create an illuminated color PostScript plot of the gridded data set
image.grd, using the intensities provided by the file intens.grd, and
color levels in the file colors.cpt, with linear scaling at 10
inch/x-unit, tickmarks every 5 units, try
grdimage image.grd -Jx10i -Ccolors.cpt -Iintens.grd -B5 > image.ps
gmt, grdcontour, grdview, grdgradient, grdhisteq
Man(1) output converted with