grdimage − Create grayshaded or colored image from a 2-D netCDF grid file |
grdimage grd_z | grd_r grd_g grd_b −Ccptfile −Jparameters [ −B[p|s]parameters ] [ −Ei|dpi ] [ −G[f|b]color ] [ −Iintensfile] [ −K ] [ −M ] [ −O ] [ −P ] [ −Q ] [ −Rwest/east/south/north[r] ] [ −S[-]b|c|l|n[/threshold] ] [ −T ] [ −U[/dx/dy/][label] ] [ −V ] [ −X[a|c|r][x-shift[u]] ] [ −Y[a|c|r][y-shift[u]] ] [ −ccopies ] [ −f[i|o]colinfo ] |
grdimage reads one 2-D gridded file and produces a
gray-shaded (or colored) map by plotting rectangles centered
on each grid node and assigning them a gray-shade (or color)
based on the z-value. Alternatively, grdimage reads
three 2-D gridded files with the red, green, and blue
components directly (all must be in the 0-255 range).
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 grid using grdgradient and, optionally,
modified by grdmath or grdhisteq. |
grd_z | grd_r grd_g grd_b |
2-D gridded data set (or red, green, blue grids) to be imaged |
−C |
name of the color palette table (for grd_z only). |
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−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. |
More details can be found in the psbasemap man pages. CYLINDRICAL PROJECTIONS: −Jclon0/lat0/scale (Cassini) AZIMUTHAL PROJECTIONS: −Jalon0/lat0/scale (Lambert) CONIC PROJECTIONS: −Jblon0/lat0/lat1/lat2/scale
(Albers) MISCELLANEOUS PROJECTIONS: −Jhlon0/scale (Hammer) NON-GEOGRAPHICAL PROJECTIONS: −Jp[a]scale[/origin][r|z]
(Polar coordinates (theta,r)) |
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. |
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−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. Specify i to use the PostScript image operator to interpolate the image at the device resolution. |
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−G |
This option only applies when the resulting image otherwise would consist of only two colors: black (0) and white (255). If so, this option will instead use the image as a transparent mask and paint the mask (or its inverse, with −Gb) with the given color combination. (See SPECIFYING COLOR below). |
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−I |
Gives the name of a grid file with intensities in the (-1,+1) range. [Default is no illumination]. |
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−K |
More PostScript code will be appended later [Default terminates the plot system]. |
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−M |
Force conversion to monochrome image using the (television) YIQ transformation. |
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−O |
Selects Overlay plot mode [Default initializes a new plot system]. |
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−P |
Selects Portrait plotting mode [GMT Default is Landscape, see gmtdefaults to change this]. |
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−Q |
Mask out nodes with z = NaN using the colormasking feature in PostScript Level 3 (the PS device must support PS Level 3). |
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−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). 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). 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 grid file will result in a subset of the grid [Default is the region given by the grid file]. |
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−S |
Select the interpolation mode by adding b for B-spline smoothing, c for bicubic interpolation, l for bilinear interpolation, or n for nearest-neighbor value (for example to plot categorical data). Optionally, prepend - to switch off antialiasing. Add /threshold to control how close to nodes with NaNs the interpolation will go. A threshold of 1.0 requires all (4 or 16) nodes involved in interpolation to be non-NaN. 0.5 will interpolate about half way from a non-NaN value; 0.1 will go about 90% of the way, etc. [Default is bicubic interpolation with antialiasing and a threshold of 0.5]. |
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−T |
This option has become OBSOLETE. Use grdview −T instead. Use −Sn to plot near-neighbor values only (use −E to increase the resolution). Use −Sn −Q to obtain something similar to the old option −Ts. The option −To is no longer supported. |
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−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. |
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−V |
Selects verbose mode, which will send progress reports to stderr [Default runs "silently"]. |
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−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. |
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−c |
Specifies the number of plot copies. [Default is 1]. |
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−f |
Special formatting of input and/or output columns (time or geographical data). Specify i or o to make this apply only to input or output [Default applies to both]. 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), or f (floating point) to each column or column range item. Shorthand −f[i|o]g means −f[i|o]0x,1y (geographic coordinates). |
To gray-shade the file hawaii_grav.grd with shades given in shades.cpt on a Lambert map at 1.5 cm/degree along the standard parallels 18 and 24, and using 1 degree tickmarks: grdimage hawaii_grav.grd −Jl18/24/1.5c −Cshades.cpt −B1 > hawaii_grav_image.ps 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: grdimage image.grd −Jx10i −Ccolors.cpt −Iintens.grd −B5 > image.ps To create an false color PostScript plot from the three gridded files red.grd, green.grd, and blue.grd, with linear scaling at 10 inch/x-unit, tickmarks every 5 units: grdimage red.grd green.grd blue.grd −Jx10i −B5 > rgbimage.ps |
GMT(1), gmt2rgb(1), grdcontour(1), grdview(1), grdgradient(1), grdhisteq(1) |