[GRASS-user] calculating perimeter per patch

[Milton Cezar Ribeiro]

Hi Markus,

Thanks for the reply. In fact a vector-based should solve this.
But, unfortulatelly, as I am working with a very large raster map
(48,000 x 60,000 pixels; 250,000 clumps), and GRASS fail when
I try r.to.vect under Windows/Vista. Is there any other options
of convert large raster maps to vector, instead of r.to.vect?

cheers
milton

2011/2/12 Markus Metz <markus.metz.giswork at googlemail.com>

> 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
> >
> > _______________________________________________
> > grass-user mailing list
> > grass-user at lists.osgeo.org
> > http://lists.osgeo.org/mailman/listinfo/grass-user
> >
> >
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.osgeo.org/pipermail/grass-user/attachments/20110212/3ef491ab/attachment.html