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)
       (r.to.rast3elev). Alternatively, 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).

   Voxel operations
       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 (v.to.rast3).  Layers from
       a 3D raster map can be converted to a 2D raster  map  (r3.to.rast).   Cross  sectional  2D
       raster   map   can  be  extracted  from  3D  raster  map  based  on  a  2D  elevation  map
       (r3.cross.rast).

   Voxel statistics
       Volume statistics can be calculated with r3.stats and r3.univar.

   Voxel interpolation
       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.

   Voxel export
       GRASS  3D  raster  maps  can be exported to VTK (r3.out.vtk).  VTK files can be visualized
       with the VTK Toolkit, Paraview and MayaVi.  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
       (r3.out.v5d).  Note that Vis5D is limited in the number of supported voxels.

       Finally, export to 3D ASCII is also available (r3.out.ascii).

   See also
       Introduction to GRASS raster map processing

       full index

       © 2008-2012 GRASS Development Team