Beyond r.param.scale, is there a good method anyone knows of to find peaks or hilltops? I'm more interested in the tops of hills/high points than the single cell that is the highest.
Thanks
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 Wednesday 18 November 2009, Michael Barton wrote:
Beyond r.param.scale, is there a good method anyone knows of to find
peaks or hilltops? I'm more interested in the tops of hills/high
points than the single cell that is the highest.Thanks
Michael
Hi,
The r.param.scale uses some common cuttoffs for curvatures to define features.
A geomorphic classification may accomplish what you are looking for, i.e.
generate some training areas that define 'summits', through in several
terrain-shape indices, and then run a supervised classification. Unsupervised
classification can sometimes work well for this kind of task, however it is
data-driven and results can vary from location to location.
Cheers,
Dylan
____________________
C. Michael Barton
Director, Center for Social Dynamics & Complexity
Professor of Anthropology, School of Human Evolution & Social Change
Arizona State UniversityPhone: 480-965-6262
Fax: 480-965-7671
www: www.public.asu.edu/~cmbarton, http://csdc.asu.edu_______________________________________________
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--
Dylan Beaudette
Soil Resource Laboratory
http://casoilresource.lawr.ucdavis.edu/
University of California at Davis
530.754.7341
On Wed, Nov 18, 2009 at 10:22 PM, Michael Barton <michael.barton@asu.edu> wrote:
Beyond r.param.scale, is there a good method anyone knows of to find peaks
or hilltops? I'm more interested in the tops of hills/high points than the
single cell that is the highest.
Perhaps r.prominence:
http://grass.osgeo.org/wiki/GRASS_AddOns#r.prominence
could be of interest?
Markus
Some friends and I had a similar problem once. We had to find hilltops
because, according to brazilian environmental legislation, they are
environmental preserves. (Top 1/3 of the mountain / hill has to be
preserved)
The way it was done to solve this was to define watersheds on an
__inverted__ DEM
Basically, once we invert the DEM, the sinks will be your peak. The
watershed area will be your mountain / hill "influence zone". The
highest and lowest elevation inside each watershed, are the hill top
and bottom elevation. The preserved area in each mountain was
everything above the 2/3 limit (top - (top-bottom)/3).
There were some other things we considered, like maximum slope but,
the basic idea was to just invert the DEM and work with watersheds...
Cheers
Daniel
PS - The entire procedure was done in another commercial GIS software
but I'm sure it can easily be done in Grass
On Wed, Nov 18, 2009 at 8:33 PM, Markus Neteler <neteler@osgeo.org> wrote:
On Wed, Nov 18, 2009 at 10:22 PM, Michael Barton <michael.barton@asu.edu> wrote:
Beyond r.param.scale, is there a good method anyone knows of to find peaks
or hilltops? I'm more interested in the tops of hills/high points than the
single cell that is the highest.Perhaps r.prominence:
http://grass.osgeo.org/wiki/GRASS_AddOns#r.prominence
could be of interest?Markus
_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user
On Wed, 18 Nov 2009, Daniel Victoria wrote:
Some friends and I had a similar problem once. We had to find hilltops
because, according to Brazilian environmental legislation, they are
environmental preserves. (Top 1/3 of the mountain / hill has to be
preserved)
Daniel,
Does this mean that the bottom 2/3 can be mined as long as the top 1/3 is
preserved? Interesting idea.
Rich
Very clever! Thanks much!
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 18, 2009, at 4:09 PM, Daniel Victoria wrote:
Some friends and I had a similar problem once. We had to find hilltops
because, according to brazilian environmental legislation, they are
environmental preserves. (Top 1/3 of the mountain / hill has to be
preserved)The way it was done to solve this was to define watersheds on an
__inverted__ DEMBasically, once we invert the DEM, the sinks will be your peak. The
watershed area will be your mountain / hill "influence zone". The
highest and lowest elevation inside each watershed, are the hill top
and bottom elevation. The preserved area in each mountain was
everything above the 2/3 limit (top - (top-bottom)/3).There were some other things we considered, like maximum slope but,
the basic idea was to just invert the DEM and work with watersheds...Cheers
Daniel
PS - The entire procedure was done in another commercial GIS software
but I'm sure it can easily be done in GrassOn Wed, Nov 18, 2009 at 8:33 PM, Markus Neteler <neteler@osgeo.org> wrote:
On Wed, Nov 18, 2009 at 10:22 PM, Michael Barton <michael.barton@asu.edu> wrote:
Beyond r.param.scale, is there a good method anyone knows of to find peaks
or hilltops? I'm more interested in the tops of hills/high points than the
single cell that is the highest.Perhaps r.prominence:
http://grass.osgeo.org/wiki/GRASS_AddOns#r.prominence
could be of interest?Markus
_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user
Well, it's not as straight forward as that. The preservation areas are
more for land cover changes and such. There is a specific part in the
legislation which states that "activities with no locational
alternatives" like mining, can occur in hill tops. There is also a
part about watershed divides (only big formations, not small divides)
The legislation is a bit complicated and filled with controversy!
After all, how do you find the hill / mountain bottom in order to
calculate the top 1/3? The environmental agencies wants the botton to
be as low as possible. The agriculture / forestry lobby wants to push
it up (they always talk about the first saddle point...). Furthermore,
the law defines what are mountains and hills. But that is not a
consensus also... That's one of the many reasons why the entire
brazilian environmental legislation is under "attack" (ops, I should
say revision)...
This is a very complicated issue that I, somehow, got involved in. But
once it became too political, I moved away from the discussions. But
if you are curious about it, fell free to ask
Cheers
Daniel
On Wed, Nov 18, 2009 at 9:18 PM, Rich Shepard <rshepard@appl-ecosys.com> wrote:
On Wed, 18 Nov 2009, Daniel Victoria wrote:
Some friends and I had a similar problem once. We had to find hilltops
because, according to Brazilian environmental legislation, they are
environmental preserves. (Top 1/3 of the mountain / hill has to be
preserved)Daniel,
Does this mean that the bottom 2/3 can be mined as long as the top 1/3 is
preserved? Interesting idea.Rich
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grass-user@lists.osgeo.org
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