[GRASS-user] r.watershed: output basin map

Pankaj_Kr_Sharma · April 19, 2012, 5:23am

Can you post please some more information related to your query.
For example : region, resolution of raster dem, command used to generated the basin.
What do you get when you query the white area.

On Thu, Apr 19, 2012 at 4:19 AM, <grass-user-request@lists.osgeo.org> wrote:

Send grass-user mailing list submissions to
grass-user@lists.osgeo.org

To subscribe or unsubscribe via the World Wide Web, visit
http://lists.osgeo.org/mailman/listinfo/grass-user
or, via email, send a message with subject or body ‘help’ to
grass-user-request@lists.osgeo.org

You can reach the person managing the list at
grass-user-owner@lists.osgeo.org

When replying, please edit your Subject line so it is more specific
than “Re: Contents of grass-user digest…”

Today’s Topics:

v.rast.stats for just a single statistic, in a python loop
(Ismael G?mez)

Re: v.rast.stats for just a single statistic, in a python
loop (Moritz Lennert)

Re: Simultaneous r.horizon processes (Hamish)

Re: v.rast.stats for just a single statistic, in a python
loop (Ismael G?mez)

r.watershed: output basin map (Rich Shepard)

Message: 1
Date: Wed, 18 Apr 2012 20:54:37 +0200
From: Ismael G?mez <gomez.ismael@gmail.com>
Subject: [GRASS-user] v.rast.stats for just a single statistic, in a
python loop
To: grass mailing list <grass-user@lists.osgeo.org>
Message-ID:
<CAN4+wUjD-9TMs_AD1Z6W5zi3TRvUsVPYfP60VUSYgeBNXLqVvQ@mail.gmail.com>
Content-Type: text/plain; charset=“iso-8859-1”

Hello,

I would like to use the v.rast.stats inside a loop in a python script.
The thing is I just need to get one of the nine columns it generates (sum).
As it runs many times in the loop, it takes a lot of (unnecessary, for this
script) time and also creates a huge table with too many (unnecessary, for
this script) columns.
I was wondering then if there was a way to specify the calculation for just
that single statistic.

Also, I wanted to ask you if there is a way to access the source code of a
specific module (in this case, v.rast.stats) via web (without downloading
the whole source code), just to have a quick look at it (and try to adapt
it to my needs, eventually contribute to it if possible, … I don’t know,
… just wondering what’s the right way to do it …).
This might be a stupid question, but please take into account that i’m
still quite new in all this (fascinating) stuff.

Thank you very much in advance.
Regards

–
Ismael G.
Ingeniero de Caminos (UPM). Ingénieur des Ponts et Chaussées (ENPC).
PhD researcher @ Urban & Land Planning Department @ ETSICCP UPM
www.caminos.upm.es +34 91 336 67 83
-------------- next part --------------
An HTML attachment was scrubbed…
URL: http://lists.osgeo.org/pipermail/grass-user/attachments/20120418/8ab10514/attachment-0001.html

Message: 2
Date: Wed, 18 Apr 2012 21:25:51 +0200
From: Moritz Lennert <mlennert@club.worldonline.be>
Subject: Re: [GRASS-user] v.rast.stats for just a single statistic, in
a python loop
To: Ismael G?mez <gomez.ismael@gmail.com>
Cc: grass mailing list <grass-user@lists.osgeo.org>
Message-ID: <4F8F153F.5080203@club.worldonline.be>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

On 18/04/12 20:54, Ismael Gómez wrote:

Hello,

I would like to use the v.rast.stats inside a loop in a python script.
The thing is I just need to get one of the nine columns it generates (sum).
As it runs many times in the loop, it takes a lot of (unnecessary, for
this script) time and also creates a huge table with too many
(unnecessary, for this script) columns.
I was wondering then if there was a way to specify the calculation for
just that single statistic.

v.rast.stats is a script, so fairly easy to modify (see below for
accessing it).

Also, I wanted to ask you if there is a way to access the source code of
a specific module (in this case, v.rast.stats) via web (without
downloading the whole source code), just to have a quick look at it (and
try to adapt it to my needs, eventually contribute to it if possible,

http://trac.osgeo.org/grass/browser/grass

For the development version (aka grass7) go to trunk, for other version
to branches.

For v.rast.stats in the 6.4 release branch:

http://trac.osgeo.org/grass/browser/grass/branches/releasebranch_6_4/scripts/v.rast.stats/v.rast.stats.

See “Download in other formats” at the bottom for downloading it.

A quick and dirty guess would be that modifying

line 247: BASECOLS=“n min max range mean stddev variance cf_var sum”

and

line 368 sed -e ‘1d’ “$STATSTMP” | awk -F “|” ‘{printf “\nUPDATE
‘${TABLE}’ SET ‘${col1}’ = %i , ‘${col2}’ = %.2f , ‘${col3}’ = %.2f ,
‘${col4}’ = %.2f , ‘${col5}’ = %.2f , ‘${col6}’ = %.2f , ‘${col7}’ =
%.2f , ‘${col8}’ = %.2f , ‘${col9}’ = %.2f WHERE ‘${KEYCOL}’ = %i;”,
$2,$3,$4,$5,$6,$7,$8,$9,$10,$1}’ > “$SQLTMP”

could actually be enough.

Moritz

Message: 3
Date: Wed, 18 Apr 2012 12:31:34 -0700 (PDT)
From: Hamish <hamish_b@yahoo.com>
Subject: Re: [GRASS-user] Simultaneous r.horizon processes
To: Collin Bode <collin@berkeley.edu>, Daniel Lee
<lee@isi-solutions.org>
Cc: GRASS user list <grass-user@lists.osgeo.org>
Message-ID:
<1334777494.42576.YahooMailClassic@web110008.mail.gq1.yahoo.com>
Content-Type: text/plain; charset=iso-8859-1

Daniel wrote:

What do you mean, r.sun can do multithreading? I’ve heard that
r.sun uses multithreading in GRASS 7, but is that implemented
in GRASS 6? Or are you talking about “poor man’s
multithreading,” like on the GRASS wiki?

there is OpenCL GPU accel. support, but it has not yet been
merged into grass 7. (mea culpa)

for r.sun being run 365 (or whatever) times in a row the “poor
man’s” method is fine, in fact the r3.in.xyz script in addons
is perhaps the most efficient multi-CPUing in grass to date.
(to my surprise)

I’ve just read through the r.horizon code in devbr6 and I don’t
see anything which makes the module unable to be run multiple
times in the same mapset. (no external region setting, no
generically named temp files, no gratuitous use of grass library
global variables) … are you running under NFS or similar as
addressed by Markus’s script? aka maybe the trouble is rooted
elsewhere?

I did a little debugging today and think it’s due to the large
size of my study area (~36 km², 0.5m resolution).

72000x72000, how much ram does r.horizon use?
maybe processes are being killed as you run out of RAM.
in that case set max num of parallel jobs so that it fits
into memory without going into swap space instead of num of CPUs.
and error handling in the script (test for ‘$? -ne 0’) could
help try failing runs again.

If I spatially partition the area and then stitch everything
back together, I hope it works - tests on smaller regions have
worked correctly thus far but I’ll need to wait a while to see
the real results.

for r.horizon the mountains in the distance can matter (that’s
the whole point) so I’d be careful with cutting up the region.
temporarily lowering the region resolution during r.horizon
may be less-bad of a compromise.

FWIW I’ve tentatively given up on using r.horizon, see the “r.sun
commissioning trials” trac ticket and wiki page. since sun
placement changes each day, and for sub degree placement of the
sun you need so many horizon maps as to make the loading of them
all more expensive than just re-calculating it on-the-fly but
with the exact placement. (I generally try for slow exactness
instead of fast processing time though, YMMV)
but maybe I don’t correctly understand what r.horizon is doing…

Hamish

Message: 4
Date: Wed, 18 Apr 2012 23:44:12 +0200
From: Ismael G?mez <gomez.ismael@gmail.com>
Subject: Re: [GRASS-user] v.rast.stats for just a single statistic, in
a python loop
To: Moritz Lennert <mlennert@club.worldonline.be>
Cc: grass mailing list <grass-user@lists.osgeo.org>
Message-ID:
<CAN4+wUjvUULZoQsPp0_VtjU79ACi2DMFWmiFo4Z2Y2dH-XFFQg@mail.gmail.com>
Content-Type: text/plain; charset=“iso-8859-1”

Thanks a million, Moritz.
Yours,
Ismael

2012/4/18 Moritz Lennert <mlennert@club.worldonline.be>

On 18/04/12 20:54, Ismael Gómez wrote:

Hello,

I would like to use the v.rast.stats inside a loop in a python script.
The thing is I just need to get one of the nine columns it generates
(sum).
As it runs many times in the loop, it takes a lot of (unnecessary, for
this script) time and also creates a huge table with too many
(unnecessary, for this script) columns.
I was wondering then if there was a way to specify the calculation for
just that single statistic.

v.rast.stats is a script, so fairly easy to modify (see below for
accessing it).

Also, I wanted to ask you if there is a way to access the source code of
a specific module (in this case, v.rast.stats) via web (without
downloading the whole source code), just to have a quick look at it (and
try to adapt it to my needs, eventually contribute to it if possible,

http://trac.osgeo.org/grass/**browser/grass<http://trac.osgeo.org/grass/browser/grass>

For the development version (aka grass7) go to trunk, for other version to
branches.

For v.rast.stats in the 6.4 release branch:

http://trac.osgeo.org/grass/browser/grass/branches/
releasebranch_6_4/scripts/v.**rast.stats/v.rast.stats<http://trac.osgeo.org/grass/browser/grass/branches/releasebranch_6_4/scripts/v.rast.stats/v.rast.stats>
.

See “Download in other formats” at the bottom for downloading it.

A quick and dirty guess would be that modifying

line 247: BASECOLS=“n min max range mean stddev variance cf_var sum”

and

line 368 sed -e ‘1d’ “$STATSTMP” | awk -F “|” ‘{printf “\nUPDATE
‘${TABLE}’ SET ‘${col1}’ = %i , ‘${col2}’ = %.2f , ‘${col3}’ = %.2f ,
‘${col4}’ = %.2f , ‘${col5}’ = %.2f , ‘${col6}’ = %.2f , ‘${col7}’ = %.2f ,
‘${col8}’ = %.2f , ‘${col9}’ = %.2f WHERE ‘${KEYCOL}’ = %i;”,
$2,$3,$4,$5,$6,$7,$8,$9,$10,$**1}’ > “$SQLTMP”

could actually be enough.

Moritz

–
Ismael G.
Ingeniero de Caminos (UPM). Ingénieur des Ponts et Chaussées (ENPC).
PhD researcher @ Urban & Land Planning Department @ ETSICCP UPM
www.caminos.upm.es +34 91 336 67 83
-------------- next part --------------
An HTML attachment was scrubbed…
URL: http://lists.osgeo.org/pipermail/grass-user/attachments/20120418/9ddc3f11/attachment-0001.html

Message: 5
Date: Wed, 18 Apr 2012 15:48:34 -0700 (PDT)
From: Rich Shepard <rshepard@appl-ecosys.com>
Subject: [GRASS-user] r.watershed: output basin map
To: grass-users@lists.osgeo.org
Message-ID:
<alpine.LNX.2.00.1204181543020.24382@salmo.appl-ecosys.com>
Content-Type: text/plain; charset=“us-ascii”

The attached pdf shows the basin map output by r.watershed based on a 10m
DEM and a threshold of 150000. The NHD level 6 subbasins are outlined in
black and the 1:24K NHD streams are in blue.

The small white areas at the bottom left and center right appear to be
external to defined sub-basins. But I don’t know how to interpret the larger
white areas with streams in them (center and top). The top margin is an
international boundary so I can understand not being able to completely
define sub-basins across that boundary since the DEM doesn’t reach that far
north, but it’s not consistently white.

Please help me interpret the white areas with vector streams.

TIA,

Rich
-------------- next part --------------
A non-text attachment was scrubbed…
Name: ebeco-basins.pdf
Type: application/pdf
Size: 32471 bytes
Desc:
Url : http://lists.osgeo.org/pipermail/grass-user/attachments/20120418/beb8bc6c/ebeco-basins.pdf

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

End of grass-user Digest, Vol 72, Issue 37