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] [ -Iintensfile] [ -K ]
[ -L[flags] ] [ -Nlevel[/r/g/b]] [ -O ] [ -P ] [ -Qtype ] [
-Rwest/east/south/north/zmin/zmax[r] ] [ -Ssmooth ] [ -T[s]
] [ -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 perspec-
tive plot by drawing a mesh, painting a colored/grayshaded
surface made up of polygons, 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 set-
ting in .gmtdefaults, but this can be overridden on the
command line by appending the c, i, or m to the
scale/width value.
CYLINDRICAL PROJECTIONS:
-Jclon0/lat0/scale (Cassini)
-Jjlon0/scale (Miller)
-Jmscale (Mercator - Greenwich and Equator as origin)
-Jmlon0/lat0/scale (Mercator - Give meridian and stan-
dard parallel)
-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 Carree))
-Jtlon0/scale (TM - Transverse Mercator, with Equator
as y = 0)
-Jtlon0/lat0/scale (TM - Transverse Mercator, set ori-
gin)
-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/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:
-Jpscale[/origin] (polar (theta,r) coordinates, option-
ally offset theta [0])
-Jxx-scale[l|ppow][/y-scale[l|ppow]] (Linear, log, and
power scaling)
More details can be found in the psbasemap manpages.
-Jz Sets the vertical scaling (for 3-D maps). Same syntax
as -Jx.
OPTIONS
No space between the option flag and the associated argu-
ments.
-B Sets map boundary tickmark intervals. See psbasemap for
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).
-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.
-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 indicating 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 provided, the frontal facade between the plane and
the data perimeter is colored.
-O Selects Overlay plot mode [Default initializes a new
plot system].
-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. 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.
-Q Select one of three settings: 1. Specify m for mesh
plot [Default], and optionally append /r/g/b for a dif-
ferent 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 resolution for the
rasterization [100]. 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.
-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 separately. Append s to skip nodes
with z = NaN. This option is useful for categorical
data where interpolating between values is meaningless.
-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.)
-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 absolute coordinates; the default (r) will reset
plot origin.
-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 draw-
ing the contours given in the color palette file hawaii.cpt
on a Lambert map at 1.5 cm/degree along the standard paral-
lels 18 and 24, with vertical scale 20 mgal/cm, and looking
at the surface from SW at 30 degree elevation, try
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 grid-
ded 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, try
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, try
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 tick-
marks every 1 degree, with intensities provided by the file
topo_intens.grd, and looking from the SE, try
grdview topography.grd -JM6i -Gmagnetics.grd
-Cmag_intens.cpt -Qs -E140/30 -Itopo_intens.grd >
draped3D.ps
BUGS
For the -Qs option: PostScript provides no way of smoothly
varying colors 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 bilinear or bicubic continuous color varia-
tions within polygons by using scanline conversion to image
the polygons.
SEE ALSO
gmt(l), grdcontour(l), grdimage(l), nearneighbor(l),
psbasemap(l), pscontour(l), pstext(l), surface(l)