[GRASS-user] inverting DEMs

[Michael Barton]

Compare

> http://www.public.asu.edu/~cmbarton/files/temp/ 
> peaks_from_terraflow.jpg

with

> http://www.public.asu.edu/~cmbarton/files/temp/peaks_from_rparamscale_minic.jpg

(new version of the r.param.scale minic output)

Michael
____________________
C. Michael Barton
Director, Center for Social Dynamics & Complexity
Professor of Anthropology, School of Human Evolution & Social Change
Arizona State University

Phone: 480-965-6262
Fax: 480-965-7671
www: www.public.asu.edu/~cmbarton, http://csdc.asu.edu







On Nov 21, 2009, at 9:38 PM, Michael Barton wrote:

> Hi Bulent,
>
> I had a chance to mess around with the inverted DEM idea tonight.
> Here's what seemed to produce the best results for identifying peaks.
>
> r.mapcalc 'inverted.DEM = -DEM'
>
> Then I ran r.terraflow on the inverted DEM to get a filled, inverted  
> DEM
>
> r.terraflow elevation=inverted.DEM filled=terraflow.filled
> direction=<required> swatershed=<required> accumulation=<required>
> tci=<required>
>
> (note that you will have to specify the other output maps too, even if
> you don't use them)
>
> In the terraflow.filled map, I set the cells with value=0 to null
> (places where the flow went off the edge of the map).
> Then I subtracted the filled map from the inverted DEM to find the
> sinks (=peaks of the original DEM)
>
> r.mapcalc 'fill.difference =inverted.DEM-terraflow.filled'
>
> If desired, these could then be inverted so that the larger the
> number, the closer to the peak.
>
> r.mapcalc 'peaks = -fill.difference'
>
> The result is draped over a relief map.
>
> http://www.public.asu.edu/~cmbarton/files/temp/ 
> peaks_from_terraflow.jpg
>
> Compare with the minic peaks map from r.param.scale
>
> http://www.public.asu.edu/~cmbarton/files/temp/peaks.jpg
>
>
> Michael
>
> ____________________
> C. Michael Barton
> Director, Center for Social Dynamics & Complexity
> Professor of Anthropology, School of Human Evolution & Social Change
> Arizona State University
>
> Phone: 480-965-6262
> Fax: 480-965-7671
> www: www.public.asu.edu/~cmbarton, http://csdc.asu.edu
>
>
>
>
>
>
>
> On Nov 21, 2009, at 10:00 AM, grass-user-request at lists.osgeo.org  
> wrote:
>
>> Date: Sat, 21 Nov 2009 07:01:37 -0700
>> From: Bulent Arikan <bulent.arikan at gmail.com>
>> Subject: [GRASS-user] inverting DEMs
>> To: grass-user at lists.osgeo.org
>> Message-ID:
>> 	<f3d3690d0911210601j2679db9bh91e39960a4eb9206 at mail.gmail.com>
>> Content-Type: text/plain; charset="iso-8859-1"
>>
>> Hi,
>>
>> I am trying to invert a DEM (i.e., make peaks basins and vice versa)
>> but
>> there does not seem to be a module for this. I am assuming this can
>> be done
>> through ' r.mapcalc ' which I have very limited experience.
>>
>> I also want to get ' r.prominence ' from the Add-ons site but the
>> text file is not downloadable. Should I copy and paste to create a
>> text
>> file that contains the script?
>>
>> Thank you for all the suggestions,
>