[GRASS-user] Plateau / Flatbed detection

GRASS GRASS user
1

Hi all,

Has anybody done or heard off a plateau (flatbed) detection? I'm
trying to automatically detect these features (Brazilian chapadas -
http://en.wikipedia.org/wiki/Chapada ) using SRTM. Anyone knows if
it's possible?

Many thanks
Daniel

2

Would a basic topographic analysis suffice, e.g. if the slope is < 5 degrees = flatbed? You can also do topographic feature classification (http://www.soi.city.ac.uk/~jwo/phd/04param.php).

--j

Daniel Victoria wrote:

Hi all,

Has anybody done or heard off a plateau (flatbed) detection? I'm
trying to automatically detect these features (Brazilian chapadas -
http://en.wikipedia.org/wiki/Chapada ) using SRTM. Anyone knows if
it's possible?

Many thanks
Daniel
_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user

--
Jonathan A. Greenberg, PhD
Postdoctoral Scholar
Center for Spatial Technologies and Remote Sensing (CSTARS)
University of California, Davis
One Shields Avenue
The Barn, Room 250N
Davis, CA 95616
Cell: 415-794-5043
AIM: jgrn307, MSN: jgrn307@hotmail.com, Gchat: jgrn307

3

It would be cool to see something like the Topographic Position Index(TPI) in GRASS.

Details here: http://www.jennessent.com/downloads/TPI-poster-TNC_18x22.pdf

-----Original Message-----
From: grass-user-bounces@lists.osgeo.org
[mailto:grass-user-bounces@lists.osgeo.org]On Behalf Of
Daniel Victoria
Sent: Friday, May 16, 2008 12:48 PM
To: grass
Subject: [GRASS-user] Plateau / Flatbed detection

Hi all,

Has anybody done or heard off a plateau (flatbed) detection? I'm
trying to automatically detect these features (Brazilian chapadas -
http://en.wikipedia.org/wiki/Chapada ) using SRTM. Anyone knows if
it's possible?

Many thanks
Daniel
_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user

4

Actually, I think r.terraflow has that! look for the TCI output!

--j

Moskovitz, Bob wrote:

It would be cool to see something like the Topographic Position Index(TPI) in GRASS.

Details here: http://www.jennessent.com/downloads/TPI-poster-TNC_18x22.pdf

-----Original Message-----
From: grass-user-bounces@lists.osgeo.org
[mailto:grass-user-bounces@lists.osgeo.org]On Behalf Of Daniel Victoria
Sent: Friday, May 16, 2008 12:48 PM
To: grass
Subject: [GRASS-user] Plateau / Flatbed detection

Hi all,

Has anybody done or heard off a plateau (flatbed) detection? I'm
trying to automatically detect these features (Brazilian chapadas -
http://en.wikipedia.org/wiki/Chapada ) using SRTM. Anyone knows if
it's possible?

Many thanks
Daniel
_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user

_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user

--
Jonathan A. Greenberg, PhD
Postdoctoral Scholar
Center for Spatial Technologies and Remote Sensing (CSTARS)
University of California, Davis
One Shields Avenue
The Barn, Room 250N
Davis, CA 95616
Cell: 415-794-5043
AIM: jgrn307, MSN: jgrn307@hotmail.com, Gchat: jgrn307

5

Thanks for all the tips guys!

My first gut reaction was to get the slope and the look for the edges
of the flatbeds and select only those edges that are close to a very
flat place.

The problem is that if there is a big mountain with steep slope
besides a plain, it will also be characterized as a flatbed.

I'll take a look at the r.terraflow TCI that Jonathan mentioned and
all the other references sent

Cheers
Daniel

On Fri, May 16, 2008 at 6:50 PM, Moskovitz, Bob
<Bob.Moskovitz@conservation.ca.gov> wrote:

It would be cool to see something like the Topographic Position Index(TPI) in GRASS.

Details here: http://www.jennessent.com/downloads/TPI-poster-TNC_18x22.pdf

-----Original Message-----
From: grass-user-bounces@lists.osgeo.org
[mailto:grass-user-bounces@lists.osgeo.org]On Behalf Of
Daniel Victoria
Sent: Friday, May 16, 2008 12:48 PM
To: grass
Subject: [GRASS-user] Plateau / Flatbed detection

Hi all,

Has anybody done or heard off a plateau (flatbed) detection? I'm
trying to automatically detect these features (Brazilian chapadas -
http://en.wikipedia.org/wiki/Chapada ) using SRTM. Anyone knows if
it's possible?

Many thanks
Daniel
_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user

6

According to the r.terraflow man page, tci is "topographic convergence index, defined as the logarithm of the ratio of flow accumulation and local slope". Based on what I read about TPI, it does not appear to be the same.

-----Original Message-----
From: grass-user-bounces@lists.osgeo.org
[mailto:grass-user-bounces@lists.osgeo.org]On Behalf Of Jonathan
Greenberg
Sent: Friday, May 16, 2008 3:51 PM
Cc: grass
Subject: Re: [GRASS-user] Plateau / Flatbed detection

Actually, I think r.terraflow has that! look for the TCI output!

--j

Moskovitz, Bob wrote:
> It would be cool to see something like the Topographic
Position Index(TPI) in GRASS.
>
> Details here:
http://www.jennessent.com/downloads/TPI-poster-TNC_18x22.pdf
>
>
>> -----Original Message-----
>> From: grass-user-bounces@lists.osgeo.org
>> [mailto:grass-user-bounces@lists.osgeo.org]On Behalf Of
>> Daniel Victoria
>> Sent: Friday, May 16, 2008 12:48 PM
>> To: grass
>> Subject: [GRASS-user] Plateau / Flatbed detection
>>
>>
>> Hi all,
>>
>> Has anybody done or heard off a plateau (flatbed) detection? I'm
>> trying to automatically detect these features (Brazilian chapadas -
>> http://en.wikipedia.org/wiki/Chapada ) using SRTM. Anyone knows if
>> it's possible?
>>
>> Many thanks
>> Daniel
>> _______________________________________________
>> grass-user mailing list
>> grass-user@lists.osgeo.org
>> http://lists.osgeo.org/mailman/listinfo/grass-user
>>
>>
> _______________________________________________
> grass-user mailing list
> grass-user@lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/grass-user
>
>

--
Jonathan A. Greenberg, PhD
Postdoctoral Scholar
Center for Spatial Technologies and Remote Sensing (CSTARS)
University of California, Davis
One Shields Avenue
The Barn, Room 250N
Davis, CA 95616
Cell: 415-794-5043
AIM: jgrn307, MSN: jgrn307@hotmail.com, Gchat: jgrn307

_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user

7

Once you digest all this info, can you summarize it to the list?

Thanks!

-----Original Message-----
From: grass-user-bounces@lists.osgeo.org
[mailto:grass-user-bounces@lists.osgeo.org]On Behalf Of
Daniel Victoria
Sent: Friday, May 16, 2008 3:52 PM
To: grass
Subject: Re: [GRASS-user] Plateau / Flatbed detection

Thanks for all the tips guys!

My first gut reaction was to get the slope and the look for the edges
of the flatbeds and select only those edges that are close to a very
flat place.

The problem is that if there is a big mountain with steep slope
besides a plain, it will also be characterized as a flatbed.

I'll take a look at the r.terraflow TCI that Jonathan mentioned and
all the other references sent

Cheers
Daniel

On Fri, May 16, 2008 at 6:50 PM, Moskovitz, Bob
<Bob.Moskovitz@conservation.ca.gov> wrote:
> It would be cool to see something like the Topographic
Position Index(TPI) in GRASS.
>
> Details here:
http://www.jennessent.com/downloads/TPI-poster-TNC_18x22.pdf
>
>> -----Original Message-----
>> From: grass-user-bounces@lists.osgeo.org
>> [mailto:grass-user-bounces@lists.osgeo.org]On Behalf Of
>> Daniel Victoria
>> Sent: Friday, May 16, 2008 12:48 PM
>> To: grass
>> Subject: [GRASS-user] Plateau / Flatbed detection
>>
>>
>> Hi all,
>>
>> Has anybody done or heard off a plateau (flatbed) detection? I'm
>> trying to automatically detect these features (Brazilian chapadas -
>> http://en.wikipedia.org/wiki/Chapada ) using SRTM. Anyone knows if
>> it's possible?
>>
>> Many thanks
>> Daniel
>> _______________________________________________
>> grass-user mailing list
>> grass-user@lists.osgeo.org
>> http://lists.osgeo.org/mailman/listinfo/grass-user
>>
>
_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user

8

> Has anybody done or heard off a plateau (flatbed) detection? I'm
> trying to automatically detect these features (Brazilian chapadas -
> http://en.wikipedia.org/wiki/Chapada ) using SRTM.

Jonathan Greenberg replied:

Would a basic topographic analysis suffice, e.g. if the
slope is < 5 degrees = flatbed?

maybe also use one of the imagery clumping/clustering tools to find wide areas of small slope. or r.slope.aspect + r.mapcalc + r.reclass + r.to.vect + v.clean remove small areas + v.to.rast ...

You can also do topographic feature
classification
(http://www.soi.city.ac.uk/~jwo/phd/04param.php).

I grass topographic feature classification is a little hidden. use:
  r.param.scale param=feature

Hamish

9

Bob wrote:

It would be cool to see something like the Topographic
Position Index(TPI) in GRASS.

Details here:
http://www.jennessent.com/downloads/TPI-poster-TNC_18x22.pdf

I remember there was an earlier thread about implementing that with GRASS.

http://search.gmane.org/?query=Topographic+Position+Index&author=&group=gmane.comp.gis.grass.user
(click on the subject of a gmane email to see the associated thread-tree)

Hamish