[GRASSLIST:5662] A r.shrink ?

Hello,
Is there any such thing as a "r.shrink" command, that would work reverse from
"r.grow" ? ie, from a given cellclump, to find the cells that are immediately
on the border, or at a given distance from the border ?
I must admit that I can't find any simple script that would do this without
much troubles (viz, without checking cells one by one...).
Thanks a lot for any input/insight
P.
--
------------------------------
Soil and Water Laboratory
Biological and Environmental Engineering Department
Cornell University
Riley-Robb Hall
ITHACA, NY 14853 - USA

On Wed, 26 Feb 2003 03:11, Soil & Water Lab. wrote:

Hello,
Is there any such thing as a "r.shrink" command, that would work
reverse from "r.grow" ? ie, from a given cellclump, to find the cells
that are immediately on the border, or at a given distance from the
border ?
I must admit that I can't find any simple script that would do this
without much troubles (viz, without checking cells one by one...).
Thanks a lot for any input/insight
P.

how about:

r.mapcalc 'neg=if(isnull(map),1,null())'
r.grow in=neg out=neg2
r.mapcalc 'map2=if(isnull(neg2),map,null())'

I've never used r.grow, so I'm not sure if I understand what its
supposed to do, but maybe the above is useful.

Hope this helps
Gordon

--

Gordon Keith
Programmer/Data Analyst
Marine Acoustics
CSIRO Marine Research
http://www.marine.csiro.au

Now the message we have heard from his Son and announce is this:
God is light, and there is no darkness at all in him."
  -- 1 John 1:5

Dear GRASS users:

Simple problem but I have not solved yet:
Reading cell values at specific positions without mouse.

I have several raster datasets and I want to extract cell values
at some specific positions on the raster data. One solution is
"d.what.rast", but it needs selection of the positions with a mouse.
Instead, I want to tell GRASS the positions with coordinate values
(latitude and longitude) from a text-file or standard I/O.

Can you please tell me appropriate commands or procedure for it?

Kenlo Nishida
kenlo@sakura.cc.tsukuba.ac.jp

On Wed, Feb 26, 2003 at 11:48:20AM +0900, Kenlo Nishida wrote:

Dear GRASS users:

Simple problem but I have not solved yet:
Reading cell values at specific positions without mouse.

I have several raster datasets and I want to extract cell values
at some specific positions on the raster data. One solution is
"d.what.rast", but it needs selection of the positions with a mouse.
Instead, I want to tell GRASS the positions with coordinate values
(latitude and longitude) from a text-file or standard I/O.

Can you please tell me appropriate commands or procedure for it?

r.what should do it...

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echo ">gra.fcw@2ztr< eryyvZ .T pveR" | rot13 | reverse