[GRASS-user] Searching Docs about 3D geological modelisation

[Benjamin Ducke]

Well, you are in luck and trouble at the same time.
Out of all GIS I know, GRASS is the only one that's
competent at handling 3D, volumetric rasters (aka
voxels, which is really what you want for 
stratigraphic models). On the other hand, efficient
voxel modelling from sparse 3D data, such as well logs
and transects remains really challenging.

The problem with well logs is also that often the data
is of a "qualitative" nature, indicating the presence
and absence of types of material. There is no interpolation
algorithm in GRASS currently which can handle that sort
of data well. 

For visualization, you can export the voxel data to VTK format
and use ParaView or VisIt, which are both superbly
powerful.

I have attached two screenshots of models that I once
produced from log data. One has been interpolated with
GRASS' 3D splines algorithm (which was a bit cheating,
really), the other is some sort of 3D IDW interpolation
done directly in VisIt.
I don't think they turned out too great.

But, hey: it's still more realistic than drawing on a piece
of paper and playing the old "connect the logs with
lines" game...

Ben


MORREALE Jean Roc wrote:
> Hello Grasslist,
> 
> I'm searching for papers, books or usecases covering the use of GRASS in 
> geology, mainly on the stratigraphic representations (well log, 
> schematic block diagram) and geomorphological (erosion, georelief 
> reconstruction) aspects.
> 
> This is an area I've not practiced so far so I would be interested to 
> know how people here deal with it  in Grass (especially their rules for 
> building a 3d model from logs and exploiting it correctly but also any 
> kind of spicy stuff you can obtain from it).
> 
> Thre is some related papers I've already find on these subjects :
> 
> HydroGIS 96: Application of Geographic Information Systems in Hydrology 
> and Water Resources Management (Proceedings of the Vienna Conference, 
> April 1996). IAHS Publ. no. 235, 1996.
> 
> Spatial Geologic Hazard Analysis in Practice, J. David Rogers, 2004
> 
> Three-dimensional Geological Modeling by FOSS GRASS GIS, Atsushi 
> Kajiyama et al., 2004
> 
> Volume modeling of soils using GRASS GIS 3D-Tools, Markus Neteler, 2001
> 
> Regards,
> MORREALE Jean Roc
> _______________________________________________
> grass-user mailing list
> grass-user at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/grass-user
> 
> 


-- 
Benjamin Ducke
Geospatial Consultant

Oxford Archaeology Digital
Janus House
Osney Mead
OX2 0ES
Oxford, U.K.

Tel: +44 (0)1865 263 800 (switchboard)
Tel: +44 (0)1865 980 758 (direct)
Fax :+44 (0)1865 793 496
benjamin.ducke at oadigital.net
http://oadigital.net






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