r.out.vtk(1grass) GRASS GIS User's Manual r.out.vtk(1grass)
NAME
r.out.vtk - Converts raster maps into the VTK-ASCII format.
KEYWORDS
raster, export, output, VTK
SYNOPSIS
r.out.vtk
r.out.vtk --help
r.out.vtk [-pstvoc] [input=name[,name,...]] [output=name] [eleva-
tion=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,green-
map,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 set-
tings (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 pro-
vided 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 me-
ters.
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 elevation-
file is given
• structured grid (not recommendet) with pointdata if an eleva-
tionfile is given
• polydataset with pointdata if an elevationfile is given (de-
fault)
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 datafor-
mats 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 transforma-
tion 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 vi-
sualize 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
SOURCE CODE
Available at: r.out.vtk source code (history)
Accessed: unknown
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GRASS 7.8.7 r.out.vtk(1grass)
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