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

Thu Jan 28 12:19:18 EST 2010

On Friday 22 January 2010, Benjamin Ducke wrote:
> Why not just ask Steve what he is concerned about and
> what he would like us to do so that he can shed his
> concerns?
> And then try to find a way to accommodate him?
> If he got more directly involved into this process,
> it might make him feel less uneasy about it.
>
> Ben

Good idea. Graham, would it be possible to forward Steve's email, so that I 
can write up and send a small summary of what we are after?

Thanks,
Dylan

> ----- Original Message -----
> From: "Dylan Beaudette" <debeaudette at ucdavis.edu>
> To: grass-user at lists.osgeo.org
> Cc: "Benjamin Ducke" <benjamin.ducke at oxfordarch.co.uk>, "Graham Fogg"
> <gef52 at mac.com> Sent: Friday, January 22, 2010 9:38:18 PM GMT +01:00
> Amsterdam / Berlin / Bern / Rome / Stockholm / Vienna Subject: Re:
> [GRASS-user] Searching Docs about 3D geological modelisation
>
> On Saturday 09 January 2010, Benjamin Ducke wrote:
> > Cheers for these. They are certainly all highly interesting.
> > Do you have an actual link for the T-PROGS software itself?
> > All I can seem to come up with are interfaces from other
> > software and publications mentioning it.
> >
> > I would certainly be interested in taking a look at your
> > GRASS interface. Is T-PROGS open source?
> >
> > My gut feeling is that the T-PROGS approach would give better
> > results than 3D kriging, as it seems better able to to
> > follow 3D shape trends:
> >
> > http://chl.erdc.usace.army.mil/chl.aspx?p=s&a=ARTICLES;37&g=50
> >
> > ... but that certainly would need testing.
> >
> > Having said that, I also like this approach for a more
> > heuristic model:
> >
> > http://chl.erdc.usace.army.mil/chl.aspx?p=s&a=ARTICLES;41&g=50
> >
> > It's very simple and could easily be implemented directly
> > in GRASS GIS. In fact, I coded something very similar to this
> > for archaeological stratigraphy reconstruction a while back.
> >
> > Cheers,
> >
> > Ben
>
> Hi Ben and others,
>
> Here are some concerns from the author of the TPROGS software:
>
> ---------------------------------------------------------------------------
>------------------------------ Steve is hesitant because he's not sure what
> the finished product would be. I think he's probably concerned about
> misapplication or perhaps some kind of ripoff. Can you provide a bit more
> background on where you see this going?
> ---------------------------------------------------------------------------
>------------------------------
>
> I think that it would be helpful to put together a small proposal,
> regarding how the TPROGS source code / ideas would be integrated into
> GRASS. It seems like the author is worried about use without citation, and
> once he understands what GRASS developers have in mind, should be for it.
>
> To start the discussion, I propose that the methods used within the TPROGS
> software be integrated (with proper citations) into a GRASS library, so
> that a series of modules can perform the multi-step process associated with
> modeling transition probabilities. Furthermore, the GRASS rast3 (voxel)
> datatype should be used to store the resulting structures-- this will make
> visualization with NVIZ / Paraview a snap.
>
> Alternatively, we may be able to link GRASS with TPROGS with a little bit
> of python glue. While this may work if there are limitations regarding the
> use of the TPROGS source, I think that having these algorithms present in
> the GRASS libraries would be a real benefit.
>
> I have CC-ed Graham, so that  we can keep him in the conversation.
>
> Cheers,
> Dylan
>
> > ----- Original Message -----
> > From: "Dylan Beaudette" <dylan.beaudette at gmail.com>
> > To: "Benjamin Ducke" <benjamin.ducke at oxfordarch.co.uk>
> > Cc: "GRASS user list" <grass-user at lists.osgeo.org>
> > Sent: Saturday, January 9, 2010 4:30:40 AM GMT +01:00 Amsterdam / Berlin
> > / Bern / Rome / Stockholm / Vienna Subject: Re: [GRASS-user] Searching
> > Docs about 3D geological modelisation
> >
> > 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.h
> > >>tm l#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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> > >> 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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-- 
Dylan Beaudette
Soil Resource Laboratory
http://casoilresource.lawr.ucdavis.edu/
University of California at Davis
530.754.7341