NAME
grdview - Create 3-D perspective grayshaded/colored image or mesh from
a 2-D grd file
SYNOPSIS
grdview relief_file -Jparameters [ -Btickinfo ] [-Ccptfile] [
-Eview_az/view_el ] [ -Gdrapefile | -Ggrd_r,grd_g,grd_b ] [ -Iintens-
file] [ -K ] [ -L[flags] ] [ -Nlevel[/r/g/b]] [ -O ] [ -P ] [ -Qtype[g]
] [ -Rwest/east/south/north/zmin/zmax[r] ] [ -Ssmooth ] [ -T[s][o[pen]]
] [ -U[/dx/dy/][label] ] [ -V ] [ -Wtype/pen ] [ -Xx-shift ] [ -Yy-
shift ] [ -Zzlevel ] [ -ccopies ]
DESCRIPTION
grdview reads a 2-D gridded 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 grd file.
relief_file
2-D gridded data set to be imaged (the relief of the surface).
-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.
-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 view point by specifying azimuth and elevation in
degrees. [Default is 180/90].
-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 gridfiles separated
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 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].
-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 r/g/b is pro-
vided, the frontal facade between the plane and the data perime-
ter is colored.
-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].
-Q Select one of four settings: 1. Specify m for mesh plot
[Default], and optionally append /r/g/b 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 mask out nodes with z = NaN using the colormasking fea-
ture in PostScript Level 3 (the PS device must support 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 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). 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.
-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"].
-Wc Draw contour lines on top of surface or mesh (not image). Append
pen attributes used for the contours. [Default: width = 3,
color = 0/0/0, texture = solid].
-Wm Sets the pen attributes used for the mesh. [Default: width = 1,
color = 0/0/0, texture = solid]. You must also select -Qm or
-Qsm for meshlines to be drawn.
-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 Sets the z-level of the basemap [0].
-c Specifies the number of plot copies. [Default is 1].
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 -Jl18/24/1.5c -Chawaii.cpt -Jz0.05c -Qm -N-100
-E225/30 -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 -Jx10.0c -Ccolor.rgb -Qs -E135/30 -Iintens.grd >
image3D.ps
To make the same plot using the rastering option with dpi = 50, use
grdview image.grd -Jx10.0c -Ccolor.rgb -Qi50 -E135/30 -Iintens.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 -JM6i -Gmagnetics.grd -Cmag_intens.cpt -Qs
-E140/30 -Itopo_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 -Glayer_%c.grd
grdview topo.grd -JM6i -Qi -E140/30 -Itopo_intens.grd
-Glayer_r.grd,layer_g.grd,layer_b.grd > image.ps
BUGS
For the -Qs option: PostScript provides no way of smoothly varying col-
ors within a polygon, so colors can only vary from polygon to polygon.
To obtain smooth images this way you may resample the grdfile(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 bilin-
ear or bicubic continuous color variations within polygons by using
scanline conversion to image the polygons.
SEE ALSO
gmt(l), gmt2rgb(l), grdcontour(l), grdimage(l), nearneighbor(l),
psbasemap(l), pscontour(l), pstext(l), surface(l)
GMT4.0 1 Oct 2004 GRDVIEW(l)
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