1. Volume modelling of soils using GRASS GIS 3D Tools
presented at
Second Italian GRASS Users Meeting, University of Trento, Feb
Markus Neteler University of Hannover
Dr. Jaro Hofierka GeoModel, Bratislava

2. Outline of Presentation
GRASS 3D volume modeling tools
Examples on soil science applications (ongoing research)
Discussion

3. GRASS 3D volume modeling tools
GRASS 3D Raster Data Model (G3D)
Data representation: raster voxels
x, y, z, w
(Rase 1998)

4. GRASS 3D volume modeling tools
3D Import
3D-ASCII sites (s.in.dbf):
name|profile3d desc|RECHTS HOCH MTIEF 1:OTIEF 2:UTIEF 3:STONR 4:IL_BOD2_ID 5:SNAS 6:FEUCH 7:ST | | |%0.0 %35.0 %1.0 %22.0 %2.0 %5.0 %1.0 % | | |%36.0 %45.0 %1.0 %22.0 %2.0 %5.0 % | | |%46.0 %110.0 %1.0 %22.0 %2.0 %5.0 % | | |%111.0 %120.0 %1.0 %22.0 %2.0 %5.0 % | | |%0.0 %30.0 %10.0 %48.0 %0.0 %5.0 % | | |%31.0 %40.0 %10.0 %14.0 %0.0 %5.0 % | | |%31.0 %40.0 %10.0 %26.0 %0.0 %5.0 % | | |%31.0 %40.0 %10.0 %43.0 %0.0 %5.0 %9.0
s.vol.idw Interpolation
s.vol.rst
s.to.rast Conversion

5. GRASS 3D volume modeling tools
3D data interpolation
s.vol.idw
Inverse Distance Weighted interpolation
s.vol.rst
Regularized Splines with Tension (Mitasova et. al)
tension parameter
gradient calculation

6. GRASS 3D volume modeling tools
3D data tools for manipulation and exploration
s.vol.rst (Mitasova et al.)
3D interpolation from sites
Gradient calculation
Horizontal and vertical aspects

7. GRASS 3D volume modeling tools
3D data tools for manipulation and exploration
r3.mapcalc (Paudits & Hofierka)
Grid volume data calculator
Operators comparing to 2D r.mapcalc
3D neighbourhood modifier: map[r,c,d]
r3.mapcalc test="if((ph_rst > 6.8) && (ph_rst < 7.1), ph_rst, null())"
pH value
pH value

8. GRASS 3D volume modeling tools
3D data export and visualization
Export to 3D sites: r3.to.sites/NVIZ

9. GRASS 3D volume modeling tools
3D data visualization
r3.mkdspf/
r3.showdspf - openGL viewer

10. GRASS 3D volume modeling tools
3D data visualization
Vis5D viewer
isolines and isosurfaces
rotate, zoom
clipping planes
slices

11. GRASS 3D volume modeling tools
3D data visualization
r3.to.v5d
Vis5D viewer
volume visualization
3D data query with cursor

12. GRASS 3D volume modeling tools
3D Examples
Study area: 3x3 km2 south of Hannover, 2m soil depth max.

13. GRASS 3D volume modeling tools
3D Soil Data
RECHTS East HOCH North MTIEF avr. depth for horizont ILDE_ID ID STONR int. profile number NR profile number OTIEF upper horizont boundary UTIEF lower horizont boundary GWS influence of g.water (class) SNAS damming wetness (class) FEUCH soil moisture (class) LGDI soil compactness STEINE stones contents ORGSUB organic matter contents KALK limestone contents (class) GWTIEFE depth to groundwater table FSAND fine sand fraction MSAND medium sand fraction GSAND coarse sand fractio nFSCHLUFF fine silt fraction MSCHLUFF medium silt fraction
GSCHLUFF coarse silt fraction TON clay fraction PHWERT pH-value KFWERT permability coefficient NGESAMT nitrate contents KAKPOT pot. cation exchange capacity SWERT sum of basic interacting cations VWERT base saturation PHOS phosphor contents BOTYP soil type (German taxonomy) KULTUR landuse MGW avr. depth to groundwater table GRUN rootable depth HORIZ letter suffixes of master horizons FARBE soil color HNBOD soil texture WURZELN rooting activity SKELETT skeletal elements contents LDSV effective compactness

14. GRASS 3D volume modeling tools
Demonstration of
Vis5D

15. GRASS 3D volume modeling tools
Conclusion
Technical view
Technology which performs on common PC
However limitations due to data intensity
Still inconsistencies to fix in 2D/3D GRASS

16. GRASS 3D volume modeling tools
Conclusion
Scientific view
Problem of 3D data availability
Note: Interpolations don't represent natural phenomena
Problem of 3D modelling within boundaries (soil units)
Time representation incomplete