[GRASS-user] calculating perimeter per patch

[Markus Metz]

Milton Cezar Ribeiro:
> Hi Markus,
>
> I will try that. The GRASS_VECTOR_LOWMEM=1 works only for G7?

Yes, only for G7. Also Large File Support for wingrass is only available in G7.

>
> Markus Metz:
>>
>> On Sat, Feb 12, 2011 at 11:58 AM, Milton Cezar Ribeiro
>> <miltinho.astronauta at gmail.com> wrote:
>> > 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?
>> >
>> No, but you could try a recent version of GRASS 7 and after starting
>> GRASS, set at the commandline
>>
>> export GRASS_VECTOR_LOWMEM=1
>>
>> then try r.to.vect
>>
>> It will take some time, but it should finish eventually.
>>
>> Markus M
>>
>> >
>> > Markus Metz:
>> >>
>> >> Milton Cezar Ribeiro:
>> >> > 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
>> >> >
>> >> >
>> >
>> >
>
>