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 <title>3D Raster data (voxel) processing in GRASS GIS</title>
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<h2>3D Raster data (voxel) in GRASS GIS</h2>

<h3>3D Raster (voxel) import</h3>

The module <a href="r3.in.ascii.html">r3.in.ascii</a> supports
generic x,y,z import. Alternatively, voxels can be generated
from 3D point vector data (<a href="v.to.rast3.html">v.to.rast3</a>). 
Always the full map is imported.
Volumes can also be created based on 2D elevation map(s) and value raster map(s)
(<a href="r.to.rast3elev.html">r.to.rast3elev</a>). Alternatively,
a volume can be composed of several 2D raster map slices which are
merged into one 3D raster volume map (<a href="r.to.rast3.html">r.to.rast3</a>).

<h3>Voxel region settings and 3D MASK</h3>

GRASS 3D raster map processing is always performed in the current 3D region
settings (see <a href="g.region.html">g.region</a>, <em>-p3</em> flags), i.e.
the current region extent, vertical extent and current 3D resolution are used.
If the 3D resolution differs from that of the input raster map(s),
on-the-fly resampling is performed (nearest neighbor resampling).
If this is not desired, the input map(s) has/have to be reinterpolated
beforehand with one of the dedicated modules.
Masks can be set (<a href="r3.mask.html">r3.mask</a>).

<h3>Voxel operations</h3>

Powerful 3D map algebra is implemented in <a href="r3.mapcalc.html">r3.mapcalc</a>.

<h3>Voxel conversion to vector or 2D raster maps</h3>

3D vector point data can be converted to a GRASS 3D raster map
(<a href="v.to.rast3.html">v.to.rast3</a>).
Layers from a 3D raster map can be converted to a 2D raster map
(<a href="r3.to.rast.html">r3.to.rast</a>).
Cross sectional 2D raster map can be extracted from 3D raster map based
on a 2D elevation map (<a href="r3.cross.rast.html">r3.cross.rast</a>).

<h3>Voxel statistics</h3>

Volume statistics can be calculated with <a href="r3.stats.html">r3.stats</a>
and <a href="r3.univar.html">r3.univar</a>.

<h3>Voxel interpolation</h3>

From 3D vector points, GRASS 3D raster maps can be interpolated
(<a href="v.vol.rst.html">v.vol.rst</a>). Results are volumes,
or 2D raster maps can be also extracted.

<h3>Voxel export</h3>

GRASS 3D raster maps can be exported to VTK (<a href="r3.out.vtk.html">r3.out.vtk</a>).
VTK files can be visualized 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>.
GRASS 2D raster maps can be exported to VTK with <a href="r.out.vtk.html">r.out.vtk</a>,
GRASS vector maps can be exported to VTK with <a href="v.out.vtk.html">v.out.vtk</a>.
<p>
Alternatively, GRASS 3D raster maps can be imported and exported from/to Vis5D
(<a href="r3.in.v5d.html">r3.in.v5d</a>, <a href="r3.out.v5d.html">r3.out.v5d</a>).
Note that Vis5D is limited in the number of supported voxels.
<p>
Finally, export to 3D ASCII is also available (<a href="r3.out.ascii.html">r3.out.ascii</a>).

<h3>See also</h3>

<a href=rasterintro.html>Introduction to GRASS raster map processing</a>

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<P>&copy; 2008 <a href="http://grass.osgeo.org">GRASS Development Team</a></P>
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