[GRASS-user] internal buffer of polygon

[Hamish]

v.in.region + v.overlay to do the inversion.

H




--- On Thu, 4/19/12, Markus Neteler <neteler at osgeo.org> wrote:

> From: Markus Neteler <neteler at osgeo.org>
> Subject: Re: [GRASS-user] internal buffer of polygon
> To: "Milton Cezar Ribeiro" <miltinho.astronauta at gmail.com>
> Cc: "GRASS user list" <grass-user at lists.osgeo.org>
> Date: Thursday, April 19, 2012, 9:17 AM
> Hi all,
> 
> does anyone have a new(er) trick for negative vector buffers
> (in GRASS 7)?
> 
> thanks
> Markus
> 
> On Thu, Oct 29, 2009 at 4:59 PM, Milton Cezar Ribeiro
> <miltinho.astronauta at gmail.com>
> wrote:
> > Hi Maning,
> >
> > Sometimes I have the same issue, but I don't solve this
> on vector.
> > Just supose you have a map where 1 is your
> raster-based-polygon
> > and NULL is outside of polygon. You can use r.mapcalc
> to
> > invert it, in the maner that 1 come to be your
> non-polygon, and
> > NULL your polygon. So you can run r.buffer with
> positive value
> > and at the end may be you need to do some kind of
> crossing
> > between original and output maps.
> >
> > Bests.
> >
> > miltinho
> >
> > 2009/10/29 maning sambale <emmanuel.sambale at gmail.com>
> >>
> >> I tried using a negative values as
> >> buffer=-3000 in v.buffer but it doesn't give me
> internal buffer in a
> >> polygon layer.
> >>
> >> Any hints?
> >>
> >> --
> >> cheers,
> >> maning
> >>
> ------------------------------------------------------
> >> "Freedom is still the most radical idea of all"
> -N.Branden
> >> wiki: http://esambale.wikispaces.com/
> >> blog: http://epsg4253.wordpress.com/
> >>
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