v.out.vtk(1grass) GRASS GIS User's Manual v.out.vtk(1grass)
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 ac-
cess 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 std-
out.
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 in-
cludes 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, visualisa-
tion errors may occur if the grass region contains coordinates greater
than 1.000.000 and vector coordinates with 0.01 - 0.001 meters precisi-
son. 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 transforma-
tion 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)
Accessed: unknown
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© 2003-2022 GRASS Development Team, GRASS GIS 7.8.7 Reference Manual
GRASS 7.8.7 v.out.vtk(1grass)
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