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

[Dylan Beaudette]

Quick update:

I recently heard back from Graham Fogg here on campus, and he is in favor of 
allowing T-PROGS to be used within GRASS. However, he is still waiting for 
the final go-ahead from the original author.

Dylan

On Monday 11 January 2010, Thomas Adams wrote:
> Dylan,
>
> Can you tell me how to obtain TPROGS? Is it only available commercially?
>
> Thanks,
> Tom
>
> Dylan Beaudette wrote:
> > Two more ideas:
> >
> > 1. conditional simulation, based on a 3D variogram model
> > 2. transition probability-based interpolation of categories
> >
> > Check out gstat for the conditional simulation, and TPROGS for the
> > transition probability. If anything is interested, I have done some
> > programming to connect GRASS and TPROGS.
> >
> > Cheers!
> >
> > Dylan
> >
> > On Fri, Jan 8, 2010 at 1:24 PM, Benjamin Ducke
> >
> > <benjamin.ducke at oxfordarch.co.uk> wrote:
> >> Woohoo, this forum is always a treasure trove
> >> of good advice. I had not idea SGemS existed!
> >> The Voronoi idea is also good, I am just not sure
> >> that the 3D Voronoi diagram is quite what one
> >> would instinctively think it is.
> >>
> >> http://en.wikipedia.org/wiki/Voronoi_diagram
> >>
> >> says: "In general a cross section of a 3D Voronoi
> >> tessellation is not a 2D Voronoi tessellation itself."
> >>
> >> Need to look into that.
> >>
> >> I don't have much practical experience
> >> with Bayes models, so can't really comment on
> >> that.
> >>
> >> Cheers,
> >>
> >> Ben
> >>
> >> Christian Kaiser wrote:
> >>> It seems to me that this is a 3D interpolation problem with categorical
> >>> variables.
> >>>
> >>> Maybe the Bayesian Maximum Entropy approach could help. There are some
> >>> interesting publications around also for geology and soil sciences, and
> >>> they can deal with categorical data as well. Look for example here:
> >>> http://www.enge.ucl.ac.be/staff/curr/Bogaert/biblioBME/BMEbibsubject.ht
> >>>ml#Soil%20Science
> >>>
> >>> Or maybe you can have a look at SGeMS (http://sgems.sourceforge.net), a
> >>> tool for 3D geostatistics.
> >>>
> >>> None of them is available through GRASS, but the algorithms are freely
> >>> available (I think open-source, but not verified).
> >>>
> >>> I am not a geologist, so please forgive if it is not adequate...
> >>>
> >>> Christian Kaiser
> >>>
> >>> On 8 janv. 2010, at 11:04, Benjamin Ducke wrote:
> >>>> Rich Shepard wrote:
> >>>>>> material. There is no interpolation algorithm in GRASS currently
> >>>>>> which can
> >>>>>> handle that sort of data well.
> >>>>>
> >>>>>  So what is needed is a political algorithm. :-)
> >>>>
> >>>> That's actually right: given the presence of n different
> >>>> layer types in the vicinity of an empty voxel, the algorithm
> >>>> would need to decide by some sort of "majority vote"
> >>>> which type to assign to that voxel.
> >>>>
> >>>>>  Kidding aside, I suspect that a fuzzy interpolation algorithm would
> >>>>> solve the problem.
> >>>>
> >>>> How? You could make the interpolated value depend on a
> >>>> fuzzy set member function, I suppose, but the situation
> >>>> here is actually so well defined that I think a probabilistic
> >>>> approach would be preferable. Since each voxel can only
> >>>> store one value, a second output map could store the
> >>>> classification probability. That may be very useful
> >>>> for visualization (you could show voxels with little
> >>>> probability hazier).
> >>>>
> >>>> Ben
> >>>>
> >>>>> Rich
> >>>>> _______________________________________________
> >>>>> 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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> >>>>
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> >>>
> >>> _______________________________________________
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> >>> 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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> >> Document Format). If you have difficulty opening them, please visit
> >> http://iso26300.info for more information.
> >>
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> >
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-- 
Dylan Beaudette
Soil Resource Laboratory
http://casoilresource.lawr.ucdavis.edu/
University of California at Davis
530.754.7341