[GRASS-user] reduce cells around the perimeters of all areas

GRASS GRASS user
1

Dear All,

I need to reduce the area in a raster map. I should do something similar to
the opposite of r.grow. I tried a method combinig r.null and r.neighbors
(option minimum) but maybe it exist a better way to do this.
Any Ideas
Thanks
Pierluigi

2

pierluigi de rosa wrote on 06/27/2007 01:06 PM:

Dear All,

I need to reduce the area in a raster map. I should do something similar to
the opposite of r.grow. I tried a method combinig r.null and r.neighbors
(option minimum) but maybe it exist a better way to do this.
Any Ideas
Thanks
  

Pierluigi,

there was some discussion about it:
http://www.nabble.com/r.shrink---tf2148082.html#a5936329
"r.shrink"

Maybe it helps (did't read it again),
Markus

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ITC -> dall'1 marzo 2007 Fondazione Bruno Kessler
ITC -> since 1 March 2007 Fondazione Bruno Kessler
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3

pierluigi de rosa wrote:

I need to reduce the area in a raster map. I should do something
similar to the opposite of r.grow. I tried a method combinig r.null
and r.neighbors (option minimum) but maybe it exist a better way to
do this.

use r.mapcalc to make a "negative" mask, then use r.grow, then r.mapcalc
again to make a positive from the grown negative.

Hamish