1GRDVIEW(1) GMT GRDVIEW(1)
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6 grdview - Create 3-D perspective image or surface mesh from a grid
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9 grdview relief_file -Jparameters [ -B[p|s]parameters ] [ -C[cpt]] [
10 -Gdrapefile | -Ggrd_r -Ggrd_g -Ggrd_b ] [ -I[intensfile|inten‐
11 sity|modifiers] ] [ -Jz|Zparameters ] [ -K ] [ -Nlevel[+gfill] ] [ -O
12 ] [ -P ] [ -Qargs[+m] ] [ -Rwest/east/south/north[/zmin/zmax][+r] ] [
13 -Ssmooth ] [ -T[s][o[pen]] ] [ -U[stamp] ] [ -Wc|m|fpen ] [
14 -Xx_offset ] [ -Yy_offset ] [ -fflags ] [ -nflags ] [ -pflags ] [
15 -ttransp ]
16 Note: No space is allowed between the option flag and the associated
18 arguments.
19
21 grdview reads a 2-D grid file and produces a 3-D perspective plot by
22 drawing a mesh, painting a colored/grayshaded surface made up of poly‐
23 gons, or by scanline conversion of these polygons to a raster image.
24 Options include draping a data set on top of a surface, plotting of
25 contours on top of the surface, and apply artificial illumination based
26 on intensities provided in a separate grid file.
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29 relief_file
30 2-D gridded data set to be imaged (the relief of the surface).
31 (See GRID FILE FORMAT below.)
32 -Jparameters (more ...)
34 Select map projection.
35 -Jz|Zparameters (more ...)
37 Set z-axis scaling; same syntax as -Jx.
38
40 -B[p|s]parameters (more ...)
41 Set map boundary frame and axes attributes.
42 -C[cpt]
44 name of the CPT. Must be present if you want (1) mesh plot with
45 contours (-Qm), or (2) shaded/colored perspective image (-Qs or
46 -Qi). For -Qs: You can specify that you want to skip a z-slice
47 by setting the red r/g/b component to -; to use a pattern give
48 red = P|ppattern[+bcolor][+fcolor][+rdpi]. Alternatively, sup‐
49 ply the name of a GMT color master dynamic CPT [rainbow] to
50 automatically determine a continuous CPT from the grid's
51 z-range. If the dynamic CPT has a default range then that range
52 will be imposed instead.
53 -Gdrapefile | -Ggrd_r -Ggrd_g -Ggrd_b
55 Drape the image in drapefile on top of the relief provided by
56 relief_file. [Default is relief_file]. Note that -Jz and -N
57 always refers to the relief_file. The drapefile only provides
58 the information pertaining to colors, which is looked-up via the
59 CPT (see -C). Alternatively, give three grid files via separate
60 -G options in the specified order. These files must contain the
61 red, green, and blue colors directly (in 0-255 range) and no CPT
62 is needed. The drapefile may be of higher resolution than the
63 relief_file.
64 -I[intensfile|intensity|modifiers]
66 Gives the name of a grid file with intensities in the (-1,+1)
67 range, or a constant intensity to apply everywhere; this simply
68 affects the ambient light. If just + is given then we derive an
69 intensity grid from the input data grid grd_z via a call to grd‐
70 gradient using the arguments -A-45 and -Nt1 for that module. You
71 can append +aazimuth and **+n*args to override those values. If
72 you want more specific intensities then run grdgradient sepa‐
73 rately first. [Default is no illumination].
74 -K (more ...)
76 Do not finalize the PostScript plot.
77 -Nlevel[+gfill]
79 Draws a plane at this z-level. If the optional color is provided
80 via the +g modifier, the frontal facade between the plane and
81 the data perimeter is colored. See -Wf for setting the pen used
82 for the outline.
83 -O (more ...)
85 Append to existing PostScript plot.
86 -P (more ...)
88 Select "Portrait" plot orientation.
89 -Qargs[+m]
91 Select one of following settings. For any of these choices, you
92 may force a monochrome image by appending the modifier +m. Col‐
93 ors are then converted to shades of gray using the (monochrome
94 television) YIQ transformation
95 1. Specify m for mesh plot [Default], and optionally append
97 color for a different mesh paint [white].
98 2. Specify mx or my for waterfall plots (row or column pro‐
100 files). Specify color as for plain m
101 3. Specify s for surface plot, and optionally append m to have
103 mesh lines drawn on top of surface.
104 4. Specify i for image plot, and optionally append the effective
106 dpi resolution for the rasterization [100].
107 5. Specify c. Same as -Qi but will make nodes with z = NaN
109 transparent, using the colormasking feature in PostScript
110 Level 3 (the PS device must support PS Level 3). .
111 -Rxmin/xmax/ymin/ymax[+r][+uunit] (more ...)
113 Specify the region of interest.
114 For perspective view p, optionally append /zmin/zmax. (more ...) This
116 option may be used to indicate the range used for the 3-D axes [Default
117 is region given by the relief_file]. You may ask for a larger w/e/s/n
118 region to have more room between the image and the axes. A smaller
119 region than specified in the relief_file will result in a subset of the
120 grid.
121 -Ssmooth
123 Smooth the contours before plotting (see grdcontour) [Default is
124 no smoothing].
125 -T[s][o[pen]]
127 Plot image without any interpolation. This involves converting
128 each node-centered bin into a polygon which is then painted sep‐
129 arately. Append s to skip nodes with z = NaN. This option is
130 useful for categorical data where interpolating between values
131 is meaningless. Optionally, append o to draw the tile outlines,
132 and specify a custom pen if the default pen is not to your lik‐
133 ing. As this option produces a flat surface it cannot be com‐
134 bined with -JZ or -Jz.
135 -U[[just]/dx/dy/][c|label] (more ...)
137 Draw GMT time stamp logo on plot.
138 -V[level] (more ...)
140 Select verbosity level [c].
141 -Wc|m|fpen
143 -Wc Draw contour lines on top of surface or mesh (not image).
145 Append pen attributes used for the contours. [Default: width
146 = 0.75p, color = black, style = solid].
147 -Wm Sets the pen attributes used for the mesh. [Default: width =
149 0.25p, color = black, style = solid]. You must also select
150 -Qm or -Qsm for meshlines to be drawn.
151 -Wf Sets the pen attributes used for the facade. [Default: width
153 = 0.25p, color = black, style = solid]. You must also select
154 -N for the facade outline to be drawn.
155 -X[a|c|f|r][x-shift[u]]
157 -Y[a|c|f|r][y-shift[u]] (more ...)
159 Shift plot origin.
160 -n[b|c|l|n][+a][+bBC][+c][+tthreshold] (more ...)
162 Select interpolation mode for grids.
163 -p[x|y|z]azim[/elev[/zlevel]][+wlon0/lat0[/z0]][+vx0/y0] (more ...)
165 Select perspective view.
166 -t[transp] (more ...)
168 Set PDF transparency level in percent.
169 -^ or just -
171 Print a short message about the syntax of the command, then
172 exits (NOTE: on Windows just use -).
173 -+ or just +
175 Print an extensive usage (help) message, including the explana‐
176 tion of any module-specific option (but not the GMT common
177 options), then exits.
178 -? or no arguments
180 Print a complete usage (help) message, including the explanation
181 of all options, then exits.
182
184 By default GMT writes out grid as single precision floats in a
185 COARDS-complaint netCDF file format. However, GMT is able to produce
186 grid files in many other commonly used grid file formats and also
187 facilitates so called "packing" of grids, writing out floating point
188 data as 1- or 2-byte integers. (more ...)
189
191 Except for Cartesian cases, we need to resample your geographic grid
192 onto an equidistant projected grid. In doing so various algorithms come
193 into play that projects data from one lattice to another while avoiding
194 anti-aliasing, leading to possible distortions. One expected effect of
195 resampling with splines is the tendency for the new resampled grid to
196 slightly exceed the global min/max limits of the original grid. If
197 this is coupled with tight CPT limits you may find that some map areas
198 may show up with fore- or background color due to the resampling. In
199 that case you have two options: (1) Modify your CPT to fit the resam‐
200 pled extrema (reported with -V) or (2) Impose clipping of resampled
201 values so they do not exceed the input min/max values (add +c to your
202 -n option).
203
205 To make a mesh plot from the file hawaii_grav.nc and drawing the con‐
206 tours given in the CPT hawaii.cpt on a Lambert map at 1.5 cm/degree
207 along the standard parallels 18 and 24, with vertical scale 20 mgal/cm,
208 and looking at the surface from SW at 30 degree elevation, run
209 gmt grdview hawaii_grav.nc -Jl18/24/1.5c -Chawaii.cpt \
211 -Jz0.05c -Qm -N-100 -p225/30 -Wc > hawaii_grav_image.ps
212 To create a illuminated color perspective plot of the gridded data set
214 image.nc, using the CPT color.rgb, with linear scaling at 10 cm/x-unit
215 and tickmarks every 5 units, with intensities provided by the file
216 intens.nc, and looking from the SE, use
217 gmt grdview image.nc -Jx10.0c -Ccolor.rgb -Qs -p135/30 -Iintens.nc > image3D.ps
219 To make the same plot using the rastering option with dpi = 50, use
221 gmt grdview image.nc -Jx10.0c -Ccolor.rgb -Qi50 -p135/30 -Iintens.nc > image3D.ps
223 To create a color PostScript perspective plot of the gridded data set
225 magnetics.nc, using the CPT mag_intens.cpt, draped over the relief
226 given by the file topography.nc, with Mercator map width of 6 inch and
227 tickmarks every 1 degree, with intensities provided by the file
228 topo_intens.nc, and looking from the SE, run
229 gmt grdview topography.nc -JM6i -Gmagnetics.nc -Cmag_intens.cpt \
231 -Qs -p140/30 -Itopo_intens.nc > draped3D.ps
232 Given topo.nc and the Landsat image veggies.ras, first run grd2rgb to
234 get the red, green, and blue grids, and then drape this image over the
235 topography and shade the result for good measure. The commands are
236 gmt grd2rgb veggies.ras -Glayer_%c.nc
238 gmt grdview topo.nc -JM6i -Qi -p140/30 -Itopo_intens.nc \
239 -Glayer_r.nc -Glayer_g.nc -Glayer_b.nc > image.ps
240
242 For the -Qs option: PostScript provides no way of smoothly varying col‐
243 ors within a polygon, so colors can only vary from polygon to polygon.
244 To obtain smooth images this way you may resample the grid file(s)
245 using grdsample or use a finer grid size when running gridding programs
246 like surface or nearneighbor. Unfortunately, this produces huge Post‐
247 Script files. The alternative is to use the -Qi option, which computes
248 bilinear or bicubic continuous color variations within polygons by
249 using scanline conversion to image the polygons.
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252 gmt, grd2rgb, gmtcolors, grdcontour, grdimage, grdsample, nearneighbor,
253 psbasemap, pscontour, pstext, surface
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256 2019, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe
2575.4.5 Feb 24, 2019 GRDVIEW(1)