GRASS and Paraview

3D visualization of GRASS data with Paraview

Download Paraview at http://www.paraview.org (available for Linux, MacOSX and MS-Windows) (screenshot gallery)

2D/3D Raster/voxel export

GRASS GIS is one of the few GIS 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 for example representations of trivariate continuous fields.

• 2D raster maps: r.out.vtk
• 3D raster (voxel) maps: r3.out.vtk

2D/3D Vector export

• 2D/3D vector maps: v.out.vtk

Visualization

Start Paraview, load VTK data, and choose the correct readers : for example "Legacy VTK file"....it is fairly intuitive to use. In the Properties section click the Apply button, next in the Display section set "Surface" in Representation menu, and set the name of the file that you had load on the Color menu. Then with Edit menu you can set the color scale. In Paraview you have many filtes to process the data. A useful filter is "Cell data to point data". In the "Filters" drop-down menu you can findn it in the "Alphabetical" list. (don't hesitate to expand this part)

paraview --data=/tmp/threelayer.vtk

3D groundwater flow

3D groundwater flow

RGB visualization

Data export with r.out.vtk:

r.out.vtk input=dsm_s_michele elevation=dsm_s_michele \
          rgbmaps=ofd_s_michele.red,ofd_s_michele.green,ofd_s_michele.blue \
          out=s_michele_color.vtk

Load into Paraview:

paraview --data=s_michele_color.vtk

• 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

Fondazione Mach - S. Michele (Italy) area shown in ParaView

Shown as stereo anaglyphs

paraview --stereo --data=s_michele_color.vtk

• 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

Fondazione Mach - S. Michele (Italy) area shown in ParaView's stereo mode

Creating Stereo anaglyphs

• see Stereo anaglyphs

See also

• GRASS 3D Workshop -- 3D data visualization with VTK: PDF handouts (S. Gebbert)
• Video tutorials: r3.out.vtk Tutorial in four parts (S. Gebbert)
• GRASS and VTK related screenshots (S. Gebbert)