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 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 .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 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]]  (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 arguments.

       -B     Sets map boundary tickmark intervals; see the psbasemap man page
              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).  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.

       -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].

       -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 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].  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 transfor-
              mation.

       -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.

       -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.

       -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, 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 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, 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 tickmarks 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 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),  grdcontour(l),  grdimage(l),  nearneighbor(l),   psbasemap(l),
       pscontour(l), pstext(l), surface(l)



GMT3.4.6                          1 Jan 2005                        GRDVIEW(l)

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