[GRASSLIST:7905] Re: Hutchinson's Adaptive Alogrithm for sound DEMs?

[orkun]

Michael Barton wrote:

>I just want to echo my support of this. My colleagues and I are trying to to
>model Holocene landforms in the Mediterranean, using DEM's created from
>Terra ASTER imagery, along with ASTER and other satellite imagery, and
>ground truthing. These kinds of additions to interpolation routines would be
>very helpful.
>
>Michael
>__________________________________________
>Michael Barton, Professor of Anthropology
>School of Human Evolution and Social Change
>Arizona State University
>Tempe, AZ 85287-2402
>
>phone: 480-965-6213
>fax: 480-965-7671
>www: http://www.public.asu.edu/~cmbarton
>
>
>
>  
>
>>From: Dylan Beaudette <dylan at iici.no-ip.org>
>>Date: Sun, 14 Aug 2005 20:51:34 -0700
>>To: Maciek Sieczka <werchowyna at epf.pl>
>>Cc: GRASS user list <grasslist at baylor.edu>
>>Subject: [GRASSLIST:7897] Re: Hutchinson's Adaptive Alogrithm for sound DEMs?
>>
>>Maciek and other GRASS users,
>>
>>These are great points to consider. My work leads me into the realm of
>>terrain analysis, so this topic is near and dear to me. I think that it
>>would be great if the pooled efforts of the GRASS community could be
>>used to make GRASS the premier DEM creation / modification environment.
>>Since the quality of a DEM is of the utmost importance when calculating
>>primary and secondary terrain parameters, documentation of and
>>confidence in the algorithms used for DEM creation should be a
>>priority.
>>
>>Currently v.surf.rst provides a very flexible means to produce
>>elevation surfaces from point and contour data. The recent work by
>>Tomas Cebecauer and others (See "Processing digital terrain models by
>>regularized spline with tension: tuning interpolation parameters for
>>different input datasets" from the proceedings to the 2002 GRASS
>>conference.) shows how v.surf.rst can be used in a method similar to
>>ANUDEM to enforce proper drainage networks, by adding a "terrain
>>skeleton".
>>
>>In addition, in reference to a recent message from David Finlayson
>>regarding cross-validation of v.surf.rst derrived data, it might be a
>>good idea for someone with some experience doing so to make a how-to
>>document. I for one am still a bit baffled at how to properly use the
>>cross-validation tools in v.surf.rst.
>>
>>Of course all of this is easy for me to say, and much harder to
>>implement. As my C skills are not the best, perhaps I  can contribute
>>to this aspect of future work in the form of documentation...
>>
>>Any thoughts, ideas from other users?
>>
>>--
>>Dylan Beaudette
>>Soils and Biogeochemistry Graduate Group
>>University of California at Davis
>>530.754.7341
>>
>>
>>On Aug 14, 2005, at 12:03 PM, Maciek Sieczka wrote:
>>
>>    
>>
>>>Helena, Markus,
>>>
>>>Since improving v.surf.rst is discussed, I would like to ad a few
>>>notes from
>>>a simple user, who doesn't understand all the maths of DEM
>>>interpolation but
>>>who would like to obtain decent results. Sorry for any naiveness.
>>>Please let
>>>me know what you think and if any of my wishes you find worthy of
>>>adding to
>>>v.surf.rst.
>>>
>>>From: "Markus Neteler" <neteler at itc.it>
>>>
>>>      
>>>
>>>>Here a FWD from Helena Mitasova:
>>>>
>>>>On Tue, Aug 02, 2005 at 07:01:33PM -0400, Helena Mitasova wrote:
>>>>        
>>>>
>>>>>We are currently testing different interpolation methods including
>>>>>topogrid (or whatever its current name is)
>>>>>          
>>>>>
>>>I gues we should call it ANUDEM - after Hutchinson. The TOPOGRID is an
>>>ArcInfo program, which is an implementation of ANUDEM v. 4.5 or 4.6.3,
>>>depending ArcInfo/ArcGIS version
>>>http://support.esri.com/index.cfm?
>>>fa=knowledgebase.techarticles.articleShow&d=20779.
>>>
>>>      
>>>
>>>>>and v.surf.rst along with other methods and we
>>>>>plan to implement modifications/improvements that we find beneficial.
>>>>>          
>>>>>
>>>If I may point 4 features I find very usefull in ANUDEM (and two other
>>>tools) for creating DEMs from data extracted from topo maps. It would
>>>be
>>>great if v.surf.rst could provide them.
>>>
>>>ANUDEM is able to utilize following data besides elevation points and
>>>contours:
>>>
>>>1. watercourses, including their flow direction
>>>I used it in TOPOGRID. At little effort - only digitise the
>>>watercourses in
>>>the direction needed - it is possible to obtain a DEM where the water
>>>flows exactly the way you want it.
>>>
>>>2. elevation discontinuity lines, called 'cliffs' in ANUDEM
>>>This was introduced in version 5.1. I haven't had an occasion to use
>>>it,
>>>since it is not available in TOPOGRID and I never had the original
>>>ANUDEM at
>>>hand. I only read it's supported in new version
>>>http://cres.anu.edu.au/outputs/anudem.php and think it is a great
>>>feature.
>>>Often elevation contour lines and points alone simply can't express
>>>all the
>>>complexity of terrain when gullies, scarps, embakments, walls, other
>>>breaklines are involved. That's due to these are not parallel to
>>>elevation
>>>isolines, thus cannot be presented as elevation isolines. Trying to
>>>represent them as points, although in theory doable in *some* cases,
>>>would
>>>require a lot of work to digitise points dense enough and to correctly
>>>estimate each point elevation manually. Yet utilising elevation
>>>discontinuity lines, digitised from topo maps, could greatly improve
>>>DEM
>>>accuracy - at very little effort. Especially in areas of land slides,
>>>erosion drived by river or flooding, land deformation due to mining,
>>>cliff
>>>shoreline - to name those I can think of right now.
>>>
>>>Such a functionality is also present in SURGE interpolation software.
>>>http://www.geocities.com/miroslavdressler/surgemain.htm
>>>But it's only freeware/shareware for Windows, not free software, is
>>>very
>>>limited as to amount of data it can handle in one turn and the input
>>>data
>>>format is non standard and pretty complex.
>>>
>>>3. waterbodies
>>>I used it in TOPOGRID. The elevation of waterbodies interpolated
>>>agreed very
>>>well with their actual elevation as seen on topo maps and they are
>>>flat like
>>>they should be. I bet many folks would find it usefull for accurate
>>>elevation representation in lakelands, visualisation of areas in the
>>>vicinity of water bodies etc.
>>>
>>>The other feature, not supported in ANUDEM but practical I think, are
>>>ridges. I found it supported in another DEM interpolation software,
>>>CatchmentSIM (again freeware for Windows, sigh), as "Interpolation
>>>Training
>>>Lines". The user can digitise them from topo maps and inlude during
>>>interpolation to model the mountain ridges in his DEM as he wishes
>>>http://www.toolkit.net.au/catchsim/.
>>>
>>>Maciek
>>>
>>>
>>>
>>>      
>>>
>
>
>
>  
>
If the subject is DEM. I can offer some:

1. Kriging interpolation in Grass to create DEM might be an idea.
(using R in grass requires a big computer memory and long time)
2. Since it is the mother of some maps, DEM is a crucial thing in GIS
applications. Any document list related with DEM may be useful.



regards

Ahmet Temiz
geologist
Earthquake Research Department
TURKEY

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