Note: A new GRASS GIS stable version has been released: GRASS GIS 7, available here. And see the new manual page here
3D Raster data (voxel) in GRASS GIS
GRASS GIS is one of the few GIS software packages with volume data support.
Here data are stored as a 3D raster with a unit volume called a voxel
(volume pixel). Voxels are designed to support representations of
trivariate continuous fields.
3D Raster (voxel) import
The module r3.in.ascii supports
generic x,y,z import. Alternatively, voxels can be generated
from 3D point vector data (v.to.rast3).
Always the full map is imported.
Volumes can also be created based on 2D elevation map(s) and value raster map(s)
a volume can be composed of several 2D raster map slices which are
merged into one 3D raster volume map (r.to.rast3).
Voxel region settings and 3D MASK
GRASS 3D raster map processing is always performed in the current 3D region
settings (see g.region, -p3 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 (r3.mask).
Powerful 3D map algebra is implemented in r3.mapcalc.
A 3D groundwater flow model is implemented in r3.gwflow.
Voxel conversion to vector or 2D raster maps
3D vector point data can be converted to a GRASS 3D raster map
Layers from a 3D raster map can be converted to a 2D raster map
Cross sectional 2D raster map can be extracted from 3D raster map based
on a 2D elevation map (r3.cross.rast).
Volume statistics can be calculated with r3.stats
From 3D vector points, GRASS 3D raster maps can be interpolated
(v.vol.rst). Results are volumes,
or 2D raster maps can be also extracted.
GRASS 3D raster maps can be exported to VTK (r3.out.vtk).
VTK files can be visualized with the
GRASS 2D raster maps can be exported to VTK with r.out.vtk,
GRASS vector maps can be exported to VTK with v.out.vtk.
Alternatively, GRASS 3D raster maps can be imported and exported from/to Vis5D
Note that Vis5D is limited in the number of supported voxels.
Finally, export to 3D ASCII is also available (r3.out.ascii).
Introduction to GRASS raster map processing
Main index - raster3D index - full index
© 2008-2012 GRASS Development Team