[GRASS-user] extracting features from DEM: how big DEM?

GRASS GRASS user
1

Dear all,

I am organizing a very large DEM for a region of interest,
and would like to know from our colleagues what is your
experience with features extraction from large DEM.
What was your highest (rows and cols) DEM that
you handled on grass? I will need to extract features
using r.watershed, r.flor, w.terraflor, and the I need
to extract several features (may be 10) from my final
(not yet ready) DEM.

Thanks in advance for the help

miltinho
brazil=toronto

2

By the way, I forgot to comment that my computer is a dell,
running vista 64 bits, with 6GB of run. I am also able to
run grass (compiled for 64bits) under Ubuntu on same machine.

Cheers

milton

2009/7/22 Milton Cezar Ribeiro <miltinho.astronauta@gmail.com>

Dear all,

I am organizing a very large DEM for a region of interest,
and would like to know from our colleagues what is your
experience with features extraction from large DEM.
What was your highest (rows and cols) DEM that
you handled on grass? I will need to extract features
using r.watershed, r.flor, w.terraflor, and the I need
to extract several features (may be 10) from my final
(not yet ready) DEM.

Thanks in advance for the help

miltinho
brazil=toronto

3

no prblem with 20000 x 20000 but takes lots of time

Milton Cezar Ribeiro pisze:

By the way, I forgot to comment that my computer is a dell,
running vista 64 bits, with 6GB of run. I am also able to
run grass (compiled for 64bits) under Ubuntu on same machine.
Cheers
milton

2009/7/22 Milton Cezar Ribeiro <miltinho.astronauta@gmail.com <mailto:miltinho.astronauta@gmail.com>>

    Dear all,
         I am organizing a very large DEM for a region of interest,
    and would like to know from our colleagues what is your
    experience with features extraction from large DEM.
    What was your highest (rows and cols) DEM that
    you handled on grass? I will need to extract features
    using r.watershed, r.flor, w.terraflor, and the I need
    to extract several features (may be 10) from my final
    (not yet ready) DEM.
         Thanks in advance for the help
         miltinho
    brazil=toronto

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4

The upper computational limit of r.watershed and r.terraflow (not 100% sure here, may be higher) is 2,147,483,647 cells. It will take a long time, r.watershed -m much longer than r.terraflow, but both modules will do it. It will be many hours if not some days for a region with 2,147,483,647 cells, so the question is how long you want to wait.

Markus M

Milton Cezar Ribeiro wrote:

Dear all,
I am organizing a very large DEM for a region of interest,
and would like to know from our colleagues what is your
experience with features extraction from large DEM.
What was your highest (rows and cols) DEM that
you handled on grass? I will need to extract features
using r.watershed, r.flor, w.terraflor, and the I need
to extract several features (may be 10) from my final
(not yet ready) DEM.
Thanks in advance for the help
miltinho
brazil=toronto
------------------------------------------------------------------------

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

5

Hi Jarek,

Thanks for the reply! What you means by lots of time? Many hours, many days or weeks?
Any comments about Windows vs Linux?

cheers

milton

2009/7/23 Jarek Jasiewicz <jarekj@amu.edu.pl>

no prblem with 20000 x 20000 but takes lots of time

Milton Cezar Ribeiro pisze:

By the way, I forgot to comment that my computer is a dell,
running vista 64 bits, with 6GB of run. I am also able to
run grass (compiled for 64bits) under Ubuntu on same machine.
Cheers
milton

2009/7/22 Milton Cezar Ribeiro <miltinho.astronauta@gmail.com mailto:[miltinho.astronauta@gmail.com](mailto:miltinho.astronauta@gmail.com)>

Dear all,
I am organizing a very large DEM for a region of interest,
and would like to know from our colleagues what is your
experience with features extraction from large DEM.
What was your highest (rows and cols) DEM that
you handled on grass? I will need to extract features
using r.watershed, r.flor, w.terraflor, and the I need
to extract several features (may be 10) from my final
(not yet ready) DEM.
Thanks in advance for the help
miltinho
brazil=toronto

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