[GRASS-user] Re: grass-user Digest, Vol 30, Issue 22

Markus,

I thought this was already in the svn. Not?

Michael
______________________________
C. Michael Barton, Professor of Anthropology
Director of Graduate Studies
School of Human Evolution & Social Change
Center for Social Dynamics & Complexity
Arizona State University
Tempe, AZ 85287-2402
USA

voice: 480-965-6262; fax: 480-965-7671
www: http://www.public.asu.edu/~cmbarton

On Oct 9, 2008, at 9:00 AM, <grass-user-request@lists.osgeo.org> wrote:

Date: Thu, 09 Oct 2008 16:38:40 +0200
From: Markus Metz <markus_metz@gmx.de>
Subject: [GRASS-user] r.watershed.fast new version
To: grass-user@lists.osgeo.org
Message-ID: <48EE1770.502@gmx.de>
Content-Type: text/plain; charset=ISO-8859-15

Hi all,

some time ago I posted a new version of r.watershed with substantial
speed increase, but still with slight differences in the outputs
compared to the original version. This problem is solved, whether or not
these differences in flow direction and flow accumulation were critical.
Now the results in flow direction and flow accumulation are 100%
identical to the original version. All other outputs are based on flow
direction and flow accumulation and therefore also identical.

The speed increase for the ram version is the same as with my first
version: e.g. a region with 22,500,000 cells is processed in 1minute 6
seconds, the original version needs 10 hours. The modified seg version
(-m flag set) needs 16 minutes (North Carolina sample data, elevation
resampled to 3 m). No idea how long the original seg version needs for
such a region, more than a day I guess.

The source code of r.watershed.fast available here
http://markus.metz.giswork.googlepages.com/r.watershed_fast_version.tar.gz

If you give this modified version a try, please let me know if it works
or not, I tested it only on Linux 32bit and Linux 64bit.

Markus

Michael,

I have no clue - AFAIK not.
I would vote to manage this in Addons (at least) for easier testing and
review.

Markus

On Thu, Oct 9, 2008 at 8:49 PM, Michael Barton <michael.barton@asu.edu> wrote:

Markus,

I thought this was already in the svn. Not?

Michael
______________________________
C. Michael Barton, Professor of Anthropology
Director of Graduate Studies
School of Human Evolution & Social Change
Center for Social Dynamics & Complexity
Arizona State University
Tempe, AZ 85287-2402
USA

voice: 480-965-6262; fax: 480-965-7671
www: http://www.public.asu.edu/~cmbarton

On Oct 9, 2008, at 9:00 AM, <grass-user-request@lists.osgeo.org> wrote:

Date: Thu, 09 Oct 2008 16:38:40 +0200
From: Markus Metz <markus_metz@gmx.de>
Subject: [GRASS-user] r.watershed.fast new version
To: grass-user@lists.osgeo.org
Message-ID: <48EE1770.502@gmx.de>
Content-Type: text/plain; charset=ISO-8859-15

Hi all,

some time ago I posted a new version of r.watershed with substantial
speed increase, but still with slight differences in the outputs
compared to the original version. This problem is solved, whether or not
these differences in flow direction and flow accumulation were critical.
Now the results in flow direction and flow accumulation are 100%
identical to the original version. All other outputs are based on flow
direction and flow accumulation and therefore also identical.

The speed increase for the ram version is the same as with my first
version: e.g. a region with 22,500,000 cells is processed in 1minute 6
seconds, the original version needs 10 hours. The modified seg version
(-m flag set) needs 16 minutes (North Carolina sample data, elevation
resampled to 3 m). No idea how long the original seg version needs for
such a region, more than a day I guess.

The source code of r.watershed.fast available here
http://markus.metz.giswork.googlepages.com/r.watershed_fast_version.tar.gz

If you give this modified version a try, please let me know if it works
or not, I tested it only on Linux 32bit and Linux 64bit.

Markus

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