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

NAME

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

KEYWORDS

       vector, export

SYNOPSIS

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

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

       -n
           Export numeric attribute table fields as VTK scalar variables

       --verbose
           Verbose module output

       --quiet
           Quiet module output

   Parameters:
       input=name
           Name of input vector map

       output=string
           Path to resulting VTK file

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

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

       scale=float
           Scale factor for elevation
           Default: 1.0

       layer=integer
           Layer number
           Default: 1

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.
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.

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

AUTHOR

       Soeren Gebbert

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       © 2003-2013 GRASS Development Team