grdview  - Create 3-D perspective grayshaded/colored image or mesh from
       a 2-D grd file


       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 ]


       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.

              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.


              -Jclon0/lat0/scale (Cassini)
              -Jjlon0/scale (Miller)
              -Jmscale (Mercator - Greenwich and Equator as origin)
              -Jmlon0/lat0/scale (Mercator - Give meridian and standard paral-
              -Joalon0/lat0/azimuth/scale  (Oblique  Mercator  -   point   and
              -Joblon0/lat0/lon1/lat1/scale (Oblique Mercator - two points)
              -Joclon0/lat0/lonp/latp/scale  (Oblique  Mercator  -  point  and
              -Jqlon0/scale (Equidistant Cylindrical  Projection  (Plate  Car-
              -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)


              -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)


              -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)


              -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
              More details can be found in the psbasemap man pages.

       -Jz    Sets the vertical scaling (for 3-D maps). Same syntax as -Jx.


       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 =

       -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-

       -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[][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-

       -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].


       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 >

       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 >

       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  >

       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 >

       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 >


       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.


       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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