[GRASS-user] Distance map with defined path

GRASS GRASS user
1

Hi List!

I was wondering if there is a way to obtain a (raster) map of distances from a point or a line, in which the path is defined by a map (i.e. a flow direction).
It would be very useful for me!

Thank you in advance.

Cheers
m.

--
Ing. Margherita Di Leo
Ph.D. Student Methods and Technologies for Environmental Monitoring
Department of Environmental Engineering and Physics (DIFA)

University of Basilicata Campus Macchia Romana
85100 - Potenza Italy

Office: +39-0971205363
Fax: +39-0971205160
E-mail: dileomargherita AT gmail DOT com
Skype: dileomargherita
URL: http://www.difa.unibas.it/A_Manager_PP.do?azione=visualizzaHomePage&id=106

2

Hi,

would [1] help ?

[1] http://grass.osgeo.org/grass64/manuals/html64_user/r.grow.distance.html

Jachym

On Thu, Jul 09, 2009 at 03:29:40PM +0200, Margherita Di Leo wrote:

Hi List!

I was wondering if there is a way to obtain a (raster) map of distances
from a point or a line, in which the path is defined by a map (i.e. a
flow direction).
It would be very useful for me!

Thank you in advance.

Cheers
m.

--
Ing. Margherita Di Leo
Ph.D. Student Methods and Technologies for Environmental Monitoring
Department of Environmental Engineering and Physics (DIFA)

University of Basilicata Campus Macchia Romana
85100 - Potenza Italy

Office: +39-0971205363
Fax: +39-0971205160
E-mail: dileomargherita AT gmail DOT com
Skype: dileomargherita
URL: http://www.difa.unibas.it/A_Manager_PP.do?azione=visualizzaHomePage&id=106

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Jachym Cepicky
e-mail: jachym.cepicky gmail com
URL: http://les-ejk.cz
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Key fingerprint: 0C6D 0EAE 76BD 506C F299 ED8A C8AB 74B8 08D4 E08F

3

Hi Jachym,

Thank you very much for your answer.

I think I was not very clear in explaining my problem. I have to calculate distance from a line, but the distance has to be calculated *following a path*, defined by a matrix of direction, as a 'flow direction' in hydrology. It would be a very useful hydrological tool.

Cheers

m.

Jachym Cepicky wrote:

Hi,

would [1] help ?

[1] http://grass.osgeo.org/grass64/manuals/html64_user/r.grow.distance.html

Jachym

On Thu, Jul 09, 2009 at 03:29:40PM +0200, Margherita Di Leo wrote:
  

Hi List!

I was wondering if there is a way to obtain a (raster) map of distances from a point or a line, in which the path is defined by a map (i.e. a flow direction).
It would be very useful for me!

Thank you in advance.

Cheers
m.

--
Eng. Margherita Di Leo
Ph.D. Student Methods and Technologies for Environmental Monitoring
Department of Environmental Engineering and Physics (DIFA)

University of Basilicata Campus Macchia Romana
85100 - Potenza Italy

Office: +39-0971205363
Fax: +39-0971205160
E-mail: dileomargherita AT gmail DOT com
Skype: dileomargherita
URL: http://www.difa.unibas.it/A_Manager_PP.do?azione=visualizzaHomePage&id=106

4

Hi Margherita,

give a look at
r.watershed
r.terraflow
r.flow

Good luck,

milton

2009/7/10 Margherita Di Leo <diregola@gmail.com>

Hi Jachym,

Thank you very much for your answer.

I think I was not very clear in explaining my problem. I have to calculate distance from a line, but the distance has to be calculated following a path, defined by a matrix of direction, as a ‘flow direction’ in hydrology. It would be a very useful hydrological tool.

Cheers

m.

Jachym Cepicky wrote:

Hi,

would [1] help ?

[1] http://grass.osgeo.org/grass64/manuals/html64_user/r.grow.distance.html

Jachym

On Thu, Jul 09, 2009 at 03:29:40PM +0200, Margherita Di Leo wrote:

Hi List!

I was wondering if there is a way to obtain a (raster) map of distances from a point or a line, in which the path is defined by a map (i.e. a flow direction).
It would be very useful for me!

Thank you in advance.

Cheers
m.

–
Eng. Margherita Di Leo
Ph.D. Student Methods and Technologies for Environmental Monitoring
Department of Environmental Engineering and Physics (DIFA)

University of Basilicata Campus Macchia Romana
85100 - Potenza Italy

Office: +39-0971205363
Fax: +39-0971205160
E-mail: dileomargherita AT gmail DOT com
Skype: dileomargherita
URL: http://www.difa.unibas.it/A_Manager_PP.do?azione=visualizzaHomePage&id=106

grass-user mailing list
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5

Hi Milton,
Thank you for answering,
I corrently use r.watershed to obtain my flow direction matrix (drainage). I'm searching for a module in which I can put this 'drainage' in input, and a raster (or vector) with the river network in input, to obtain in output a matrix in wich in each cell there is the distance from the river, calculated on the basis of the path defined in 'drainage'.

Thank you
m.

Milton Cezar Ribeiro wrote:

Hi Margherita,
give a look at
r.watershed
r.terraflow
r.flow
Good luck,
milton
2009/7/10 Margherita Di Leo <diregola@gmail.com <mailto:diregola@gmail.com>>

    Hi Jachym,

    Thank you very much for your answer.

    I think I was not very clear in explaining my problem. I have to
    calculate distance from a line, but the distance has to be
    calculated *following a path*, defined by a matrix of direction,
    as a 'flow direction' in hydrology. It would be a very useful
    hydrological tool.

    Cheers

    m.

    Jachym Cepicky wrote:

        Hi,

        would [1] help ?

        [1]
        http://grass.osgeo.org/grass64/manuals/html64_user/r.grow.distance.html

        Jachym

        On Thu, Jul 09, 2009 at 03:29:40PM +0200, Margherita Di Leo wrote:
         
            Hi List!

            I was wondering if there is a way to obtain a (raster) map
            of distances from a point or a line, in which the path is
            defined by a map (i.e. a flow direction).
            It would be very useful for me!

            Thank you in advance.

            Cheers
            m.

--
Eng. Margherita Di Leo
Ph.D. Student Methods and Technologies for Environmental Monitoring
Department of Environmental Engineering and Physics (DIFA)

University of Basilicata Campus Macchia Romana
85100 - Potenza Italy

Office: +39-0971205363
Fax: +39-0971205160
E-mail: dileomargherita AT gmail DOT com
Skype: dileomargherita
URL: http://www.difa.unibas.it/A_Manager_PP.do?azione=visualizzaHomePage&id=106

6

On Thu, Jul 9, 2009 at 3:29 PM, Margherita Di Leo<diregola@gmail.com> wrote:

Hi List!

I was wondering if there is a way to obtain a (raster) map of distances from
a point or a line, in which the path is defined by a map (i.e. a flow
direction).
It would be very useful for me!

if I understand what you mean, r.cost should do it:
http://grass.osgeo.org/screenshots/raster.php
-> Example Distance to water (r.cost)

The r.cost manual page contains an example.

Markus

7

On 10/07/09 14:00, Margherita Di Leo wrote:

Hi Milton,
Thank you for answering,
I corrently use r.watershed to obtain my flow direction matrix (drainage). I'm searching for a module in which I can put this 'drainage' in input, and a raster (or vector) with the river network in input, to obtain in output a matrix in wich in each cell there is the distance from the river, calculated on the basis of the path defined in 'drainage'.

Maybe by setting all cells other than the drainage paths to null ? Or by using a mask which only leaves the drainage paths ? I don't know how r.grow.distance handles null cells ?

In vector space you could maybe use v.distance upload=to_along...

Moritz

8

Hi Markus,

Thanks for the hint! I'm trying with r.cost (but it is veeeeery slow!)

Cheers

margherita

Markus Neteler wrote:

On Thu, Jul 9, 2009 at 3:29 PM, Margherita Di Leo<diregola@gmail.com> wrote:
  

Hi List!

I was wondering if there is a way to obtain a (raster) map of distances from
a point or a line, in which the path is defined by a map (i.e. a flow
direction).
It would be very useful for me!
    
if I understand what you mean, r.cost should do it:
http://grass.osgeo.org/screenshots/raster.php
-> Example Distance to water (r.cost)

The r.cost manual page contains an example.

Markus

--
Eng. Margherita Di Leo
Ph.D. Student Methods and Technologies for Environmental Monitoring
Department of Environmental Engineering and Physics (DIFA)

University of Basilicata Campus Macchia Romana
85100 - Potenza Italy

Office: +39-0971205363
Fax: +39-0971205160
E-mail: dileomargherita AT gmail DOT com
Skype: dileomargherita
URL: http://www.difa.unibas.it/A_Manager_PP.do?azione=visualizzaHomePage&id=106

9

Hi Margherita,

On Wed, Jul 15, 2009 at 8:03 AM, Margherita Di Leo<diregola@gmail.com> wrote:

Hi Markus,

Thanks for the hint! I'm trying with r.cost (but it is veeeeery slow!)

since yesterday night (European time) r.terracost (GRASS Addons)
seem to produce reasonable results.
Please consider to try as well!

ciao
Markus