[GRASSLIST:1877] distance between points in a raster map

GRASS GRASS user
1

Hi,

I'm looking for calculating a raster map for which each pixel

is the distance to a only one specified point (or pixel).

I would enjoy if someone has a solution (command, script,

mapcalc procedure) for this quite simple problem.

Yours

--
Francois DELCLAUX
------------------------------------------------------------
UMR HydroSciences Montpellier
BP 5045 34032 Montpellier Cedex FRANCE
http://www.mpl.ird.fr/hydrologie/mevhysa
mailto: delclaux@msem.univ-montp2.fr
Tel : (33) (0)4 67 14 90 11 Fax : (33) (0)4 67 14 47 74
------------------------------------------------------------

2

Create a raster layer where each cell is given the value of your cell resolution
(such as "30" for 30 meteres). Run r.cost over this layer, using your specified
point as the starting point. Although the current flavor of r.cost is a little
odd (adding the averaged value of the current cell plus the cell it is spreading
to), this shouldn't be a problem with a cost surface of identical values.

Best regards,
  -Malcolm Williamson
   CAST - University of Arkansas

Francois Delclaux wrote:

Hi,

I'm looking for calculating a raster map for which each pixel

is the distance to a only one specified point (or pixel).

I would enjoy if someone has a solution (command, script,

mapcalc procedure) for this quite simple problem.

Yours

--
Francois DELCLAUX
------------------------------------------------------------
UMR HydroSciences Montpellier
BP 5045 34032 Montpellier Cedex FRANCE
http://www.mpl.ird.fr/hydrologie/mevhysa
mailto: delclaux@msem.univ-montp2.fr
Tel : (33) (0)4 67 14 90 11 Fax : (33) (0)4 67 14 47 74
------------------------------------------------------------

3

On Fri, May 25, 2001 at 01:18:40PM +0000, Francois Delclaux wrote:

Hi,

I'm looking for calculating a raster map for which each pixel

is the distance to a only one specified point (or pixel).

I would enjoy if someone has a solution (command, script,

mapcalc procedure) for this quite simple problem.

Hi Francois,

probably r.distance is what you are looking for?

http://www.geog.uni-hannover.de/grass/gdp/html_grass5/html/r.distance.html

In combination with r.clump you could re-number each pixel for
individual distance queries.

Regards

Markus Neteler