university of hannover inst. of physical geography and landscape ecology volume modelling of soils...

University of HannoverInst. of Physical Geography and Landscape Ecology

Volume modelling of soils using GRASS

GIS 3D Tools

presented at

Second Italian GRASS Users Meeting,University of Trento, Feb. 1-2 2001

Markus NetelerUniversity of Hannover

Dr. Jaro Hofierka GeoModel, Bratislava


Outline of Presentation

GRASS 3D volume modeling tools

Examples on soil science applications(ongoing research)

Discussion



GRASS 3D Raster Data Model (G3D)

Data representation: raster voxels

x, y, z, w(Rase 1998)



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:ST3570018.000000|5766419.000000|-17.500000|%0.0 %35.0 %1.0 %22.0 %2.0 %5.0 %1.0 %3570018.000000|5766419.000000|-40.500000|%36.0 %45.0 %1.0 %22.0 %2.0 %5.0 %1.03570018.000000|5766419.000000|-78.000000|%46.0 %110.0 %1.0 %22.0 %2.0 %5.0 %1.03570018.000000|5766419.000000|-115.500000|%111.0 %120.0 %1.0 %22.0 %2.0 %5.0 %13570378.000000|5766152.000000|-15.000000|%0.0 %30.0 %10.0 %48.0 %0.0 %5.0 %9.03570378.000000|5766152.000000|-35.500000|%31.0 %40.0 %10.0 %14.0 %0.0 %5.0 %9.03570773.000000|5766415.000000|-35.500000|%31.0 %40.0 %10.0 %26.0 %0.0 %5.0 %9.03570773.000000|5766415.000000|-35.500000|%31.0 %40.0 %10.0 %43.0 %0.0 %5.0 %9.0

s.vol.idw Interpolation

s.vol.rst

s.to.rast3 Conversion



3D data interpolation

s.vol.idw

Inverse Distance Weighted interpolation

s.vol.rst

Regularized Splines with Tension (Mitasova et. al)

tension parameter gradient calculation



3D data tools for manipulation and exploration

s.vol.rst (Mitasova et al.) 3D interpolation from sites

Gradient calculation

Horizontal and vertical aspects



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



3D data export and visualization

Export to 3D sites: r3.to.sites/NVIZ



3D data visualization

r3.mkdspf/

r3.showdspf - openGL viewer




Vis5D viewer

isolines andisosurfaces

rotate, zoom

clipping planes

slices




r3.to.v5d

Vis5D viewer

volume visualization

3D data query withcursor



3D Examples

Study area: 3x3 km2 south of Hannover, 2m soil depth max.



3D Soil Data RECHTS East

HOCH NorthMTIEF avr. depth for horizontILDE_ID IDSTONR int. profile numberNR profile numberOTIEF upper horizont boundaryUTIEF lower horizont boundaryGWS influence of g.water (class)SNAS damming wetness (class)FEUCH soil moisture (class)LGDI soil compactnessSTEINE stones contentsORGSUB organic matter contentsKALK limestone contents (class)GWTIEFE depth to groundwater tableFSAND fine sand fractionMSAND medium sand fractionGSAND coarse sand fractionFSCHLUFF fine silt fractionMSCHLUFF medium silt fraction

GSCHLUFF coarse silt fractionTON clay fractionPHWERT pH-valueKFWERT permability coefficientNGESAMT nitrate contentsKAKPOT pot. cation exchange capacitySWERT sum of basic interacting cationsVWERT base saturationPHOS phosphor contentsBOTYP soil type (German taxonomy)KULTUR landuseMGW avr. depth to groundwater tableGRUN rootable depthHORIZ letter suffixes of master horizonsFARBE soil colorHNBOD soil textureWURZELN rooting activitySKELETT skeletal elements contentsLDSV effective compactness



Demonstration of

Vis5D



Conclusion

Technical view

Technology which performs on common PC

However limitations due to data intensity

Still inconsistencies to fix in 2D/3D GRASS



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

university of hannover inst. of physical geography and landscape ecology volume modelling of soils...

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