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grdview(1)                            GMT                           grdview(1)




NAME

       grdview - Create 3-D perspective image or surface mesh from a grid


SYNOPSIS

       grdview  relief_file  -Jparameters [  -B[p|s]parameters ] [  -C[cpt]] [
       -Gdrapefile |  -Ggrd_r   -Ggrd_g   -Ggrd_b  ]  [   -I[intensfile|inten-
       sity|modifiers]  ] [ -Jz|Zparameters ] [ -K ] [  -Nlevel[+gfill] ] [ -O
       ] [ -P ] [  -Qargs[+m] ] [  -Rwest/east/south/north[/zmin/zmax][+r] ] [
       -Ssmooth ] [  -T[s][o[pen]] ] [  -U[stamp] ] [  -Wtypepen ] [  -Xx_off-
       set ] [  -Yy_offset ] [ -nflags ] [ -pflags ] [ -ttransp ]

       Note: No space is allowed between the option flag  and  the  associated
       arguments.


DESCRIPTION

       grdview  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 raster image.
       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.


REQUIRED ARGUMENTS

       relief_file
              2-D gridded data set to be imaged (the relief of  the  surface).
              (See GRID FILE FORMAT below.)

       -Jparameters (more a|)
              Select map projection.

       -Jz|Zparameters (more a|)
              Set z-axis scaling; same syntax as -Jx.


OPTIONAL ARGUMENTS

       -B[p|s]parameters (more a|)
              Set map boundary frame and axes attributes.

       -C[cpt]
              name  of the CPT. 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 the red r/g/b component to -; to use a  pattern  give
              red  = P|ppattern[+bcolor][+fcolor][+rdpi].  Alternatively, sup-
              ply the name of a GMT color  master  dynamic  CPT  [rainbow]  to
              automatically   determine  a  continuous  CPT  from  the  gridas
              z-range.  If the dynamic CPT has a default range then that range
              will be imposed instead.

        -Gdrapefile |  -Ggrd_r  -Ggrd_g  -Ggrd_b
              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  (see -C). Alternatively, give three grid files via separate
              -G options in the specified order. These files must contain  the
              red, green, and blue colors directly (in 0-255 range) and no CPT
              is needed. The drapefile may be of higher  resolution  than  the
              relief_file.

       -I[intensfile|intensity|modifiers]
              Gives  the  name  of a grid file with intensities in the (-1,+1)
              range, or a constant intensity to apply everywhere; this  simply
              affects the ambient light.  If just + is given then we derive an
              intensity grid from the input data grid grd_z via a call to grd-
              gradient using the arguments -A-45 and -Nt1 for that module. You
              can append +aazimuth and **+n*args to override those values.  If
              you  want  more  specific intensities then run grdgradient sepa-
              rately first.  [Default is no illumination].

       -K (more a|)
              Do not finalize the PostScript plot.

       -Nlevel[+gfill]
              Draws a plane at this z-level. If the optional color is provided
              via  the  +g  modifier, the frontal facade between the plane and
              the data perimeter is colored. See -Wf for setting the pen  used
              for the outline.

       -O (more a|)
              Append to existing PostScript plot.

       -P (more a|)
              Select aPortraita plot orientation.

       -Qargs[+m]
              Select  one of following settings. For any of these choices, you
              may force a monochrome image by appending the modifier +m.  Col-
              ors  are  then converted to shades of gray using the (monochrome
              television) YIQ transformation

              1. Specify m for mesh  plot  [Default],  and  optionally  append
                 color for a different mesh paint [white].

              2. Specify  mx  or  my  for  waterfall plots (row or column pro-
                 files). Specify color as for plain m

              3. Specify s for surface plot, and optionally append m  to  have
                 mesh lines drawn on top of surface.

              4. Specify i for image plot, and optionally append the effective
                 dpi resolution for the rasterization [100].

              5. Specify c. Same as -Qi but will  make  nodes  with  z  =  NaN
                 transparent,  using  the  colormasking  feature in PostScript
                 Level 3 (the PS device must support PS Level 3). .

       -Rxmin/xmax/ymin/ymax[+r][+uunit] (more a|)
              Specify the region of interest.

       For perspective view p, optionally append /zmin/zmax.  (more  a|)  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.

       -Ssmooth
              Smooth the contours before plotting (see grdcontour) [Default is
              no smoothing].

       -T[s][o[pen]]
              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.

       -U[[just]/dx/dy/][c|label] (more a|)
              Draw GMT time stamp logo on plot.

       -V[level] (more a|)
              Select verbosity level [c].

       -Wtypepen

          -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, style = solid].

          -Wm    Sets  the pen attributes used for the mesh. [Default: width =
                 0.25p, color = black, style = 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, style = solid]. You must also  select
                 -N for the facade outline to be drawn.

       -X[a|c|f|r][x-shift[u]]

       -Y[a|c|f|r][y-shift[u]] (more a|)
              Shift plot origin.

       -n[b|c|l|n][+a][+bBC][+c][+tthreshold] (more a|)
              Select interpolation mode for grids.

       -p[x|y|z]azim[/elev[/zlevel]][+wlon0/lat0[/z0]][+vx0/y0] (more a|)
              Select perspective view.

       -t[transp] (more a|)
              Set PDF transparency level in percent.

       -^ or just -
              Print  a  short  message  about  the syntax of the command, then
              exits (NOTE: on Windows just use -).

       -+ or just +
              Print an extensive usage (help) message, including the  explana-
              tion  of  any  module-specific  option  (but  not the GMT common
              options), then exits.

       -? or no arguments
              Print a complete usage (help) message, including the explanation
              of all options, then exits.


GRID FILE FORMATS

       By  default  GMT  writes  out  grid  as  single  precision  floats in a
       COARDS-complaint netCDF file format. However, GMT is  able  to  produce
       grid  files  in  many  other  commonly  used grid file formats and also
       facilitates so called apackinga of grids, writing  out  floating  point
       data as 1- or 2-byte integers. (more a|)


CONSEQUENCES OF GRID RESAMPLING

       Except  for  Cartesian  cases, we need to resample your geographic grid
       onto an equidistant projected grid. In doing so various algorithms come
       into play that projects data from one lattice to another while avoiding
       anti-aliasing, leading to possible distortions.  One expected effect of
       resampling  with  splines is the tendency for the new resampled grid to
       slightly exceed the global min/max limits of  the  original  grid.   If
       this  is coupled with tight CPT limits you may find that some map areas
       may show up with fore- or background color due to the  resampling.   In
       that  case  you have two options: (1) Modify your CPT to fit the resam-
       pled extrema (reported with -V) or (2)  Impose  clipping  of  resampled
       values  so  they do not exceed the input min/max values (add +c to your
       -n option).


EXAMPLES

       To make a mesh plot from the file hawaii_grav.nc and drawing  the  con-
       tours  given  in  the  CPT 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 elevation, run

              gmt grdview hawaii_grav.nc -Jl18/24/1.5c -Chawaii.cpt \
                          -Jz0.05c -Qm -N-100 -p225/30 -Wc > hawaii_grav_image.ps

       To  create a illuminated color perspective plot of the gridded data set
       image.nc, using the CPT color.rgb, with linear scaling at 10  cm/x-unit
       and  tickmarks  every  5  units,  with intensities provided by the file
       intens.nc, and looking from the SE, use

              gmt grdview image.nc -Jx10.0c -Ccolor.rgb -Qs -p135/30 -Iintens.nc > image3D.ps

       To make the same plot using the rastering option with dpi = 50, use

              gmt grdview image.nc -Jx10.0c -Ccolor.rgb -Qi50 -p135/30 -Iintens.nc > image3D.ps

       To create a color PostScript perspective plot of the gridded  data  set
       magnetics.nc,  using  the  CPT  mag_intens.cpt,  draped over the relief
       given by the file topography.nc, with Mercator map width of 6 inch  and
       tickmarks  every  1  degree,  with  intensities  provided  by  the file
       topo_intens.nc, and looking from the SE, run

              gmt grdview topography.nc -JM6i -Gmagnetics.nc -Cmag_intens.cpt \
                          -Qs -p140/30 -Itopo_intens.nc > draped3D.ps

       Given topo.nc and the Landsat image veggies.ras, first run  grd2rgb  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

              gmt grd2rgb veggies.ras -Glayer_%c.nc
              gmt grdview topo.nc -JM6i -Qi -p140/30 -Itopo_intens.nc \
                         -Glayer_r.nc -Glayer_g.nc -Glayer_b.nc > image.ps


REMARKS

       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  grid  file(s)
       using grdsample or use a finer grid size when running gridding programs
       like surface or nearneighbor. Unfortunately, this produces  huge  Post-
       Script  files. The alternative is to use the -Qi option, which computes
       bilinear or bicubic continuous  color  variations  within  polygons  by
       using scanline conversion to image the polygons.


SEE ALSO

       gmt(1), grd2rgb(1), gmtcolors(5), grdcontour(1), grdimage(1),
       grdsample(1), nearneighbor(1), psbasemap(1), pscontour(1), pstext(1),
       surface(1)


COPYRIGHT

       2017, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe



5.4.2                            Jun 24, 2017                       grdview(1)

gmt5 5.4.2 - Generated Thu Jun 29 08:32:33 CDT 2017
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