[GRASS-user] calculating perimeter per patch

[Markus Metz]

On Sat, Feb 12, 2011 at 5:11 AM, Milton Cezar Ribeiro
<miltinho.astronauta at gmail.com> wrote:
> Dear all,
>
> I have a raster map where each patch (i.e. forest fragment) have different
> ID.
> I need to estimate the perimeter per patch, but R.le.patch can't do the job.

Have you tried a vector approach? Then the perimeter can be simply uploaded with
v.to.db option=perimeter.

(Watch out for the fractal problem, both r.le.patch and v.to.db)

Markus M

> ------------
> GRASS 6.4> r.le.patch map=fragments sam=w per=p1 siz=s1 out=STATS.txt
>
> PARAMETER CHOICES:
>         MAP:      fragments
>         SAMPLE:   whole map     TRACING:  8 neighbor
>         SIZE MEASURES:
>                   mean patch size
>         PERIMETER MEASURES:
>                   sum of perims
>
> R.LE.PATCH IS WORKING....;
>
> ERROR: G_calloc: unable to allocate 24806 * 8 bytes at alloc_cell.c:83
> ------------
>
> Any hint?
>
> bests
>
> milton
>
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