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<h2>NAME</h2>
<em><b>r.out.vtk</b></em> - Converts raster maps into the VTK-Ascii format
<h2>KEYWORDS</h2>
raster
<h2>SYNOPSIS</h2>
<b>r.out.vtk</b><br>
<b>r.out.vtk help</b><br>
<b>r.out.vtk</b> [-<b>pstvoc</b>] <b>input</b>=<em>name</em>[,<i>name</i>,...] [<b>output</b>=<em>string</em>] [<b>elevation</b>=<em>string</em>] [<b>null</b>=<em>float</em>] [<b>elevation2d</b>=<em>float</em>] [<b>rgbmaps</b>=<em>string</em>[,<i>string</i>,...]] [<b>vectormaps</b>=<em>string</em>[,<i>string</i>,...]] [<b>elevscale</b>=<em>float</em>] [<b>dp</b>=<em>integer</em>] [--<b>verbose</b>] [--<b>quiet</b>]
<h3>Flags:</h3>
<DL>
<DT><b>-p</b></DT>
<DD>Create VTK point data instead of VTK cell data (if no elevation map is given)</DD>
<DT><b>-s</b></DT>
<DD>Use structured grid for elevation (not recommended)</DD>
<DT><b>-t</b></DT>
<DD>Use polydata-trianglestrips for elevation grid creation</DD>
<DT><b>-v</b></DT>
<DD>Use polydata-vertices for elevation grid creation (to use with vtkDelauny2D)</DD>
<DT><b>-o</b></DT>
<DD>Scale factor effects the origin (if no elevation map is given)</DD>
<DT><b>-c</b></DT>
<DD>Correct the coordinates to fit the VTK-OpenGL precision</DD>
<DT><b>--verbose</b></DT>
<DD>Verbose module output</DD>
<DT><b>--quiet</b></DT>
<DD>Quiet module output</DD>
</DL>
<h3>Parameters:</h3>
<DL>
<DT><b>input</b>=<em>name[,<i>name</i>,...]</em></DT>
<DD>Name of input raster map(s)</DD>
<DT><b>output</b>=<em>string</em></DT>
<DD>Name for VTK-ASCII output file</DD>
<DT><b>elevation</b>=<em>string</em></DT>
<DD>Elevation raster map</DD>
<DT><b>null</b>=<em>float</em></DT>
<DD>Value to represent no data cell</DD>
<DD>Default: <em>-10.0</em></DD>
<DT><b>elevation2d</b>=<em>float</em></DT>
<DD>Elevation (if no elevation map is specified)</DD>
<DD>Default: <em>0.0</em></DD>
<DT><b>rgbmaps</b>=<em>string[,<i>string</i>,...]</em></DT>
<DD>Three (r,g,b) raster maps to create rgb values [redmap,greenmap,bluemap]</DD>
<DT><b>vectormaps</b>=<em>string[,<i>string</i>,...]</em></DT>
<DD>Three (x,y,z) raster maps to create vector values [xmap,ymap,zmap]</DD>
<DT><b>elevscale</b>=<em>float</em></DT>
<DD>Scale factor for elevation</DD>
<DD>Default: <em>1.0</em></DD>
<DT><b>dp</b>=<em>integer</em></DT>
<DD>Number of significant digits (floating point only)</DD>
<DD>Options: <em>0-20</em></DD>
<DD>Default: <em>12</em></DD>
</DL>
<H2>DESCRIPTION</H2>
Outputs <I>Raster</I> maps in <I>VTK-ASCII</I> format. <I>Map's</I> are
valid Raster map's in the current mapset. <I>output</I> is the name of
an VTK-ASCII file which will be written in the current working directory.
If <I>output</I> is not specified then <B>stdout</B> is used.
The module is sensitive to region settings (set with g.region).
<br>
<br>
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 provided in meters.
If the elevation values are in a different unit than meters, use
the scale parameter to convert the units.
<br>
<br>
If no elevation map is given, the user can set the hight 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 meters.
<br>
<br>
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.
<br>
<br>
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.
<H2>NOTES</H2>
This filter generates:
<ul>
<li><I>structured points</I> with <I>celldata</I> or <I>pointdata</I> if no elevationfile is given</li>
<li><I>structured grid</I> (not recommendet) with <I>pointdata</I> if an elevationfile is given</li>
<li><I>polydataset</I> with <I>pointdata</I> if an elevationfile is given (default)</li>
</ul>
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
<EM><A HREF="http://www.vtk.org">VTK Toolkit</A></EM>,
<EM><A HREF="http://www.paraview.org">Paraview</A></EM> and
<EM><A HREF="http://mayavi.sourceforge.net">MayaVi</A></EM> 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
choosen null value in the VTK-ASCII file.
<br>
If elevation map is choosen, a polygonal grid is created with <i>quads</i>,
but the user can choose also <i>triangle strips</i> or <i>vertices</i>.
These dataformats a documented at <EM><A HREF="http://www.vtk.org">VTK Toolkit</A></EM>.
<br>
<br>
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 center point of the default region).
<br>
<br>
<H3>Difference between point- and celldata</H3>
r.out.vtk can export raster cells with different representations.
<ul>
<li>
<I>pointdata</I> -- 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.
</li>
<li>
<I>celldata</I> -- 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 visualize one value at a time.
</li>
</ul>
<H2>EXAMPLE</H2>
<H3>Simple Spearfish example</H3>
<div class="code"><pre>
#set a nice region
g.region -d
g.region n=4926970 s=4914857 w=591583 e=607793 res=50
#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
</pre></div>
<H3>Spearfish example with RGB data</H3>
<div class="code"><pre>
#set the region
g.region -d
g.region n=4926970 s=4914857 w=591583 e=607793 res=50
#we are using r.in.onearth (available from the grass addon wiki) to create rgb data
#get some satellite images with r.in.onearth
r.in.onearth -l output=Sat tmband=Red
r.in.onearth -l output=Sat tmband=IR1
r.in.onearth -l output=Sat tmband=IR2
#export the data
r.out.vtk rgbmaps=SatLandsatTM_IR1,SatLandsatTM_IR2,SatLandsatTM_Red elevation=elevation.10m output=/tmp/out.vtk
# visualize in paraview or other VTK viewer:
paraview --data=/tmp/out.vtk
</pre></div>
<br>
<H2>SEE ALSO</H2>
<EM><A HREF="r3.out.vtk.html">r3.out.vtk</A></EM><br>
<EM><A HREF="r.out.ascii.html">r.out.ascii</A></EM><br>
<EM><A HREF="g.region.html">g.region</A></EM><br>
<H2>AUTHORS</H2>
Soeren Gebbert
<p><i>Last changed: $Date: 2007-07-03 19:37:26 +0200 (Tue, 03 Jul 2007) $</i>
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