Provided by: grass-doc_6.4.3-3_all bug


       v.out.vtk  - Converts a GRASS binary vector map to VTK ASCII output.


       vector, export


       v.out.vtk help
       v.out.vtk  [-cn]  input=name   [output=string]   [type=string[,string,...]]   [dp=integer]
       [scale=float]   [layer=integer]   [--verbose]  [--quiet]

           Correct the coordinates to fit the VTK-OpenGL precision

           Export numeric attribute table fields as VTK scalar variables

           Verbose module output

           Quiet module output

           Name of input vector map

           Path to resulting VTK file

           Feature type
           Options: point,kernel,centroid,line,boundary,area,face
           Default: point,kernel,centroid,line,boundary,area,face

           Number of significant digits (floating point only)

           Scale factor for elevation
           Default: 1.0

           Layer number
           Default: 1


       v.out.vtk converts a GRASS vector map in binary format to the VTK ASCII output.

       If the output parameter is not given, the output will be send to stdout.


       The following vector types can be exported together in one VTK ascii file:
       point line centroid boundary area face
       Category data (cat) for the selected vector type and layer will be written as scalar  data
       with  name  "cat_{vectorname}". If no cat exists, the value will set to -1 as normal cat's
       are always positive.  If a vector has  more  categories  in  one  layer,  only  the  first
       category will be exported.
       All  numeric  attribute fields of a given layer of the input map can be exported as scalar
       VTK variables using the "-n" flag.
       3d vectors are supported by default. The created VTK data  always  includes  x,  y  and  z
       coordinates  (z  =  0  if  not a 3d vector map).  Note that you can easily convert your 2d
       vectors into 3d vectors with v.drape.
       Because of the 32bit limits of OpenGL which is  used  by  VTK,  visualisation  errors  may
       occure  if  the  grass  region  contains  coordinates  greater  than  1.000.000 and vector
       coordinates with 0.01 - 0.001 meters precisison. For this reason, the flag "-c" was added.
       The coordinates are transformed to smaller coordinates (by decreasing the coordinates with
       the region center).
       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 default region).
       The GRASS vector data is converted into the polydata format of VTK:
       vtk  Vertices  --  representing  points  and centroids vtk lines -- representing lines and
       boundaries vtk polygons -- representing areas and faces

       The VTK file can be visualized with VTK Toolkit, Paraview and MayaVi.

       If areas or faces are exported, the data  have  to  be  triangulated  within  Paraview  or


       Spearfish example:

       Export the soils with cats in layer 1:
       v.out.vtk input=soils type=area layer=1 output=/tmp/soils.vtk
        Export the streams with cats in layer 1:
       v.out.vtk input=streams type=line layer=1 output=/tmp/streams.vtk
        Write the archsite vtk output to stdout with cats in layer 1:
       v.out.vtk input=archsites type=point layer=1




       Soeren Gebbert

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