NAME

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

KEYWORDS

       vector, export, output, VTK

SYNOPSIS

       v.out.vtk
       v.out.vtk --help
       v.out.vtk  [-cn]  input=name   [layer=string]   [output=name]   [type=string[,string,...]]
       [precision=integer]   [zscale=float]    [--overwrite]   [--help]   [--verbose]   [--quiet]
       [--ui]

   Flags:
       -c
           Correct the coordinates to fit the VTK-OpenGL precision

       -n
           Export numeric attribute table fields as VTK scalar variables

       --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 [required]
           Name of input vector map
           Or data source for direct OGR access

       layer=string
           Layer number or name
           Vector  features  can have category values in different layers. This number determines
           which layer to use. When used with direct OGR access this is the layer name.
           Default: 1

       output=name
           Name for output VTK file

       type=string[,string,...]
           Input feature type
           Options: point, kernel, centroid, line, boundary, area, face
           Default: point,kernel,centroid,line,boundary,area,face

       precision=integer
           Number of significant digits (floating point only)

       zscale=float
           Scale factor for elevation
           Default: 1.0

DESCRIPTION

       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.

NOTES

       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.
       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 occur
       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.

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

EXAMPLE

       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

SEE ALSO

        v.out.ascii
       r.out.vtk
       r3.out.vtk

AUTHOR

       Soeren Gebbert

SOURCE CODE

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

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       © 2003-2019 GRASS Development Team, GRASS GIS 7.8.2 Reference Manual