GRDVIEW(1) Generic Mapping Tools GRDVIEW(1)NAMEgrdview - Create 3-D perspective grayshaded/colored image or mesh from
a 2-D grid file
SYNOPSISgrdview relief_file -Jparameters [ -B[p|s]parameters ] [ -Ccptfile ] [
-Eazim/elev[+wlon/lat[/z]][+vx0/y0] ] [ -Gdrapefile |
-Ggrd_r,grd_g,grd_b ] [ -Iintensfile ] [ -Jz|Zparameters ] [ -K ] [
-L[flags] ] [ -Nlevel[/color] ] [ -O ] [ -P ] [ -Qtype[g] ] [
-Rwest/east/south/north[/zmin/zmax][r] ] [ -Ssmooth ] [ -T[s][o[pen]] ]
[ -U[just/dx/dy/][c|label] ] [ -V ] [ -Wtype/pen ] [ -X[a|c|r][x-
shift[u]] ] [ -Y[a|c|r][y-shift[u]] ] [ -Zzlevel ] [ -ccopies ]
DESCRIPTIONgrdview reads a 2-D grid file and produces a 3-D perspective plot by
drawing a mesh, painting a colored/grayshaded surface made up of poly‐
gons, or by scanline conversion of these polygons to a rasterimage.
Options include draping a data set on top of a surface, plotting of
contours on top of the surface, and apply artificial illumination based
on intensities provided in a separate grid file.
relief_file
2-D gridded data set to be imaged (the relief of the surface).
(See GRID FILE FORMAT below.)
-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. When central meridian is optional,
default is center of longitude range on -R option. Default
standard parallel is the equator. For map height, max dimen‐
sion, or min dimension, append h, +, or - to the width, respec‐
tively.
More details can be found in the psbasemap man pages.
CYLINDRICAL PROJECTIONS:
-Jclon0/lat0/scale (Cassini)
-Jcyl_stere/[lon0/[lat0/]]scale (Cylindrical Stereographic)
-Jj[lon0/]scale (Miller)
-Jm[lon0/[lat0/]]scale (Mercator)
-Jmlon0/lat0/scale (Mercator - Give meridian and standard paral‐
lel)
-Jo[a]lon0/lat0/azimuth/scale (Oblique Mercator - point and
azimuth)
-Jo[b]lon0/lat0/lon1/lat1/scale (Oblique Mercator - two points)
-Joclon0/lat0/lonp/latp/scale (Oblique Mercator - point and
pole)
-Jq[lon0/[lat0/]]scale (Cylindrical Equidistant)
-Jtlon0/[lat0/]scale (TM - Transverse Mercator)
-Juzone/scale (UTM - Universal Transverse Mercator)
-Jy[lon0/[lat0/]]scale (Cylindrical Equal-Area)
CONIC PROJECTIONS:
-Jblon0/lat0/lat1/lat2/scale (Albers)
-Jdlon0/lat0/lat1/lat2/scale (Conic Equidistant)
-Jllon0/lat0/lat1/lat2/scale (Lambert Conic Conformal)
-Jpoly/[lon0/[lat0/]]scale ((American) Polyconic)
AZIMUTHAL PROJECTIONS:
-Jalon0/lat0[/horizon]/scale (Lambert Azimuthal Equal-Area)
-Jelon0/lat0[/horizon]/scale (Azimuthal Equidistant)
-Jflon0/lat0[/horizon]/scale (Gnomonic)
-Jglon0/lat0[/horizon]/scale (Orthographic)
-Jglon0/lat0/altitude/azimuth/tilt/twist/Width/Height/scale
(General Perspective).
-Jslon0/lat0[/horizon]/scale (General Stereographic)
MISCELLANEOUS PROJECTIONS:
-Jh[lon0/]scale (Hammer)
-Ji[lon0/]scale (Sinusoidal)
-Jkf[lon0/]scale (Eckert IV)
-Jk[s][lon0/]scale (Eckert VI)
-Jn[lon0/]scale (Robinson)
-Jr[lon0/]scale (Winkel Tripel)
-Jv[lon0/]scale (Van der Grinten)
-Jw[lon0/]scale (Mollweide)
NON-GEOGRAPHICAL PROJECTIONS:
-Jp[a]scale[/origin][r|z] (Polar coordinates (theta,r))
-Jxx-scale[d|l|ppow|t|T][/y-scale[d|l|ppow|t|T]] (Linear, log,
and power scaling)
-Jz Sets the vertical scaling (for 3-D maps). Same syntax as -Jx.
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.
-C name of the color palette file. Must be present if you want (1)
mesh plot with contours (-Qm), or (2) shaded/colored perspective
image (-Qs or -Qi). For -Qs: You can specify that you want to
skip a z-slice by setting red = -; to use a pattern give red =
P|pdpi/pattern[:Fr/g/b[Br/g/b]].
-E Sets the viewpoint's azimuth and elevation (for perspective
view) [180/90]. For frames used for animation, you may want to
append + to fix the center of your data domain (or specify a
particular world coordinate point with +wlon0/lat[/z]) which
will project to the center of your page size (or specify the
coordinates of the projected view point with +vx0/y0).
-G Drape the image in drapefile on top of the relief provided by
relief_file. [Default is relief_file]. Note that -Jz and -N
always refers to the relief_file. The drapefile only provides
the information pertaining to colors, which is looked-up via the
cpt file (see -C). Alternatively, give three grid files sepa‐
rated by commas. These files must contain the red, green, and
blue colors directly (in 0-255 range) and no cpt file is needed.
The drapefile may be of higher resolution than the relief_file.
-I Gives the name of a grid file with intensities in the (-1,+1)
range. [Default is no illumination].
-K More PostScript code will be appended later [Default terminates
the plot system].
-L Boundary condition flags may be x or y or xy indicating data is
periodic in range of x or y or both, or flags may be g indicat‐
ing geographical conditions (x and y are lon and lat). [Default
uses "natural" conditions (second partial derivative normal to
edge is zero).] If no flags are set, use bilinear rather than
the default bicubic resampling when draping is required.
-N Draws a plane at this z-level. If the optional color is pro‐
vided, the frontal facade between the plane and the data perime‐
ter is colored. See -Wf for setting the pen used for the out‐
line. (See SPECIFYING COLOR below).
-O Selects Overlay plot mode [Default initializes a new plot sys‐
tem].
-P Selects Portrait plotting mode [Default is Landscape, see gmtde‐
faults to change this].
-Q Select one of four settings: 1. Specify m for mesh plot
[Default], and optionally append /color for a different mesh
paint [white]. 2. Specify s for surface plot, and optionally
append m to have mesh lines drawn on top of surface. 3. Specify
i for image plot, and optionally append the effective dpi reso‐
lution for the rasterization [100]. 4. Specify c. Same as -Qi
but will make nodes with z = NaN transparent, using the color‐
masking feature in PostScript Level 3 (the PS device must sup‐
port PS Level 3). For any of these choices, you may force a
monochrome image by appending g. Colors are then converted to
shades of gray using the (television) YIQ transformation.
-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 lati‐
tude). Alternatively, specify the name of an existing grid file
and the -R settings (and grid spacing, if applicable) are copied
from the grid. 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 delim‐
iters and their type and positions must be exactly as indicated
(however, input, output and plot formats are customizable; see
gmtdefaults). This option may be used to indicate the range
used for the 3-D axes [Default is region given by the
relief_file]. 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 relief_file will result in a subset of the
grid.
-S Smooth the contours before plotting (see grdcontour) [Default is
no smoothing].
-T Plot image without any interpolation. This involves converting
each node-centered bin into a polygon which is then painted sep‐
arately. Append s to skip nodes with z = NaN. This option is
useful for categorical data where interpolating between values
is meaningless. Optionally, append o to draw the tile outlines,
and specify a custom pen if the default pen is not to your lik‐
ing. As this option produces a flat surface it cannot be com‐
bined with -JZ or -Jz. (See SPECIFYING PENS below).
-U Draw Unix System time stamp on plot. By adding just/dx/dy/, the
user may specify the justification of the stamp and where the
stamp should fall on the page relative to lower left corner of
the plot. For example, BL/0/0 will align the lower left corner
of the time stamp with the lower left corner of the plot.
Optionally, append a label, or c (which will plot the command
string.). The GMT parameters UNIX_TIME, UNIX_TIME_POS, and
UNIX_TIME_FORMAT can affect the appearance; see the gmtdefaults
man page for details. The time string will be in the locale set
by the environment variable TZ (generally local time).
-V Selects verbose mode, which will send progress reports to stderr
[Default runs "silently"].
-Wc Draw contour lines on top of surface or mesh (not image).
Append pen attributes used for the contours. [Default: width =
0.75p, color = black, texture = solid]. (See SPECIFYING PENS
below).
-Wm Sets the pen attributes used for the mesh. [Default: width =
0.25p, color = black, texture = solid]. You must also select
-Qm or -Qsm for meshlines to be drawn.
-Wf Sets the pen attributes used for the facade. [Default: width =
0.25p, color = black, texture = solid]. You must also select -N
for the facade outline to be drawn. (See SPECIFYING PENS
below).
-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.
-Z Sets the z-level of the basemap [Default is the bottom of the z-
axis].
-c Specifies the number of plot copies. [Default is 1].
SPECIFYING PENS
pen The attributes of lines and symbol outlines as defined by pen is
a comma delimetered list of width, color and texture, each of
which is optional. width can be indicated as a measure (points,
centimeters, inches) or as faint, thin[ner|nest], thick[er|est],
fat[ter|test], or obese. color specifies a gray shade or color
(see SPECIFYING COLOR below). texture is a combination of
dashes `-' and dots `.'.
SPECIFYING COLOR
color The color of lines, areas and patterns can be specified by a
valid color name; by a gray shade (in the range 0-255); by a
decimal color code (r/g/b, each in range 0-255; h-s-v, ranges
0-360, 0-1, 0-1; or c/m/y/k, each in range 0-1); or by a hexa‐
decimal color code (#rrggbb, as used in HTML). See the gmtcol‐
ors manpage for more information and a full list of color names.
GRID FILE FORMATS
GMT is able to recognize many of the commonly used grid file formats,
as well as the precision, scale and offset of the values contained in
the grid file. When GMT needs a little help with that, you can add the
suffix =id[/scale/offset[/nan]], where id is a two-letter identifier of
the grid type and precision, and scale and offset are optional scale
factor and offset to be applied to all grid values, and nan is the
value used to indicate missing data. See grdreformat(1) and Section
4.17 of the GMT Technical Reference and Cookbook for more information.
When reading a netCDF file that contains multiple grids, GMT will read,
by default, the first 2-dimensional grid that can find in that file. To
coax GMT into reading another multi-dimensional variable in the grid
file, append ?varname to the file name, where varname is the name of
the variable. Note that you may need to escape the special meaning of ?
in your shell program by putting a backslash in front of it, or by
placing the filename and suffix between quotes or double quotes. See
grdreformat(1) and Section 4.18 of the GMT Technical Reference and
Cookbook for more information, particularly on how to read splices of
3-, 4-, or 5-dimensional grids.
EXAMPLES
To make a mesh plot from the file hawaii_grav.grd and drawing the con‐
tours given in the color palette file hawaii.cpt on a Lambert map at
1.5 cm/degree along the standard parallels 18 and 24, with vertical
scale 20 mgal/cm, and looking at the surface from SW at 30 degree ele‐
vation, run
grdview hawaii_grav.grd -Jl 18/24/1.5c -C hawaii.cpt -Jz 0.05c -Qm
-N-100 -E 225/30 -Wc > hawaii_grav_image.ps
To create a illuminated color perspective plot of the gridded data set
image.grd, using the color palette file color.rgb, with linear scaling
at 10 cm/x-unit and tickmarks every 5 units, with intensities provided
by the file intens.grd, and looking from the SE, use
grdview image.grd -Jx 10.0c -C color.rgb -Qs -E 135/30 -I intens.grd >
image3D.ps
To make the same plot using the rastering option with dpi = 50, use
grdview image.grd -Jx 10.0c -C color.rgb -Qi 50 -E 135/30 -I intens.grd
> image3D.ps
To create a color PostScript perspective plot of the gridded data set
magnetics.grd, using the color palette file mag_intens.cpt, draped over
the relief given by the file topography.grd, with Mercator map width of
6 inch and tickmarks every 1 degree, with intensities provided by the
file topo_intens.grd, and looking from the SE, run
grdview topography.grd -JM 6i -G magnetics.grd -C mag_intens.cpt -Qs -E
140/30 -I topo_intens.grd > draped3D.ps
Given topo.grd and the Landsat image veggies.ras, first run gmt2rgb to
get the red, green, and blue grids, and then drape this image over the
topography and shade the result for good measure. The commands are
gmt2rgb veggies.ras -G layer_%c.grd
grdview topo.grd -JM 6i -Qi-E 140/30 -I topo_intens.grd -G
layer_r.grd,layer_g.grd,layer_b.grd > image.ps
REMARKS
For the -Qs option: PostScript provides no way of smoothly varying
colors within a polygon, so colors can only vary from polygon to poly‐
gon. To obtain smooth images this way you may resample the grid
file(s) using grdsample or use a finer grid size when running gridding
programs like surface or nearneighbor. Unfortunately, this produces
huge PostScript files. The alternative is to use the -Qi option, which
computes bilinear or bicubic continuous color variations within poly‐
gons by using scanline conversion to image the polygons.
SEE ALSOGMT(1), gmt2rgb(1), gmtcolors(5), grdcontour(1), grdimage(1),
nearneighbor(1), psbasemap(1), pscontour(1), pstext(1), surface(1)GMT 4.5.14 1 Nov 2015 GRDVIEW(1)
