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NAME

       r.out.vtk  - Converts raster maps into the VTK-ASCII format.

KEYWORDS

       raster, export, VTK

SYNOPSIS

       r.out.vtk
       r.out.vtk --help
       r.out.vtk    [-pstvoc]     [input=name[,name,...]]      [output=name]     [elevation=name]
       [null=float]                    [z=float]                    [rgbmaps=string[,string,...]]
       [vectormaps=string[,string,...]]    [zscale=float]    [precision=integer]    [--overwrite]
       [--help]  [--verbose]  [--quiet]  [--ui]

   Flags:
       -p
           Create VTK point data instead of VTK cell data (if no elevation map is given)

       -s
           Use structured grid for elevation (not recommended)

       -t
           Use polydata-trianglestrips for elevation grid creation

       -v
           Use polydata-vertices for elevation grid creation (to use with vtkDelauny2D)

       -o
           Scale factor affects the origin (if no elevation map is given)

       -c
           Correct the coordinates to match the VTK-OpenGL precision

       --overwrite
           Allow output files to overwrite existing files

       --help
           Print usage summary

       --verbose
           Verbose module output

       --quiet
           Quiet module output

       --ui
           Force launching GUI dialog

   Parameters:
       input=name[,name,...]
           Raster map(s) to be converted to VTK-ASCII data format

       output=name
           Name for VTK-ASCII output file

       elevation=name
           Name of input elevation raster map

       null=float
           Value to represent no data cell
           Default: -99999.99

       z=float
           Constant elevation (if no elevation map is specified)
           Default: 0.0

       rgbmaps=string[,string,...]
           Three (r,g,b) raster maps to create RGB values [redmap,greenmap,bluemap]

       vectormaps=string[,string,...]
           Three (x,y,z) raster maps to create vector values [xmap,ymap,zmap]

       zscale=float
           Scale factor for elevation
           Default: 1.0

       precision=integer
           Number of significant digits (floating point only)
           Options: 0-20
           Default: 12

DESCRIPTION

       Outputs raster maps in VTK-ASCII format. Map’s are  valid  raster  map’s  in  the  current
       mapset.   output  is  the  name  of an VTK-ASCII file which will be written in the current
       working directory.  If output is not  specified  then  stdout  is  used.   The  module  is
       sensitive to region settings (set with g.region).

       Elevation,  scaling,  point/celldata, vector and RGB Data are supported.  If the map is in
       LL projection, the elevation values will automatically scaled to degrees. It  is  supposed
       that  the  elevation  values  are  provided  in  meters.  If the elevation values are in a
       different unit than meters, use the scale parameter to convert the units.

       If no elevation map is given, the user can set the height of the map by one value.   Point
       or  cell  data  are  available.  Also  scaling is supported for this elevation value.  The
       elevation value must be provided in meters.

       The RGB input requires three raster maps: red, green, blue  - in  this  order.   The  maps
       must have values between 0 and 255, otherwise you will get lots of warnings and the values
       are set to 0.  More than one RGB dataset (3 maps) is not supported.

       The vector input requires three raster maps: x, y, z -- defining the vector coordinates  -
       in this order.  More than one vector dataset (3 maps) is not supported.

NOTES

       This filter generates:

           ·   structured points with celldata or pointdata if no elevationfile is given

           ·   structured grid (not recommendet) with pointdata if an elevationfile is given

           ·   polydataset with pointdata if an elevationfile is given (default)
       and  puts  this  in a simple VTK-ASCII file. Nor XML or binary output are supported. It is
       possible to choose more then one raster map to be written  to  the  VTK-ASCII  file.  Each
       cell-/pointdata  is  named like the raster map it represents.  You can visualize this file
       with the VTK Toolkit, Paraview and MayaVi which are based on VTK.  If you  have  a  raster
       map with partly no data, use the threshold filter in paraview to visualize the valid data.
       Just filter all data which is greater/lesser than the chosen null value in  the  VTK-ASCII
       file.
       If  elevation  map  is  chosen,  a  polygonal grid is created with quads, but the user can
       choose also triangle strips or vertices.  These dataformats a documented at VTK Toolkit.

       If the "-c" flag is used and the data  should  be  visualised  together  with  other  data
       exported  via *.out.vtk modules, be sure the "-c" flag was also set in these modules.  But
       this will only work with data  from  the  SAME  location  (The  reference  point  for  the
       coordinates transformation is based on the center point of the default region).

   Difference between point- and celldata
       r.out.vtk can export raster cells with different representations.

           ·   pointdata  -- the cells/values are represented by the center of the cell.  Instead
               of cells, points are created. Each point can hold different values, but  the  user
               can only visualize one value at a time. These points can be connected in different
               ways.

           ·   celldata -- is only provided if no elevation map is given.  The cells are  created
               with  the  same  hight and width as in GRASS. Each cell can hold different values,
               but the user can only visualize one value at a time.

EXAMPLE

   Simple Spearfish example
       # set region
       g.region n=4926970 s=4914857 w=591583 e=607793 res=50 -p
       # export the data
       r.out.vtk input=elevation.10m,slope,aspect elevation=elevation.10m output=/tmp/out.vtk
       # visualize in Paraview or other VTK viewer:
       paraview --data=/tmp/out.vtk

   Spearfish example with RGB data
       #set the region
       g.region n=4926990 s=4914840 w=591570 e=607800 res=30 -p
       # using r.in.wms to create RGB data to get a satellite coverage
       r.in.wms layers=global_mosaic mapserver=http://wms.jpl.nasa.gov/wms.cgi \
                output=wms_global_mosaic
       # export the data to VTK
       r.out.vtk rgbmaps=wms_global_mosaic.red,wms_global_mosaic.green,wms_global_mosaic.blue \
                 elevation=elevation.10m output=/tmp/out.vtk
       # visualize in Paraview or other VTK viewer:
       paraview --data=/tmp/out.vtk
       Paraview RGB visualization notes
       To achieve proper RGB overlay:

           ·   In Paraview, click "Apply"

           ·   Select the "Display" tab and choose "Color by" to switch from input scalars to rgb
               scalars

           ·   Disable  the  "Map  Scalars" check button in the display tab to avoid the use of a
               lookup table

SEE ALSO

        r3.out.vtk, r.out.ascii, g.region
       GRASS and Paraview Wiki page

AUTHOR

       Soeren Gebbert

       Last changed: $Date: 2014-11-28 15:27:38 +0100 (Fri, 28 Nov 2014) $

SOURCE CODE

       Available at: r.out.vtk source code (history)

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       © 2003-2019 GRASS Development Team, GRASS GIS 7.6.1 Reference Manual