selecting edges in vectorsX

[Rick Thompson]

Hi,
  This is a bit round-a-bout, but would this work:
1) r.poly
2) v.llabel the lines
3) v.to.rast the lines
4) buffer the lines
5) r.mapcalc finallines = 'if((buffer) && (data == 4 || data == 5))'
6) r.thin the finallines
7) r.line the finallines

Rick

On Thu, 22 Feb 1996, Agustin Lobo wrote:

> I'd like to do the following:
> 1. Assume I have a raster thematic image (land cover types).
> 2. I vectorise with r.poly
> 3. Now I would like to select those vector lines that are
> boundaries between 2 given classes, i.e., lines that are
> edges between type 4 and type 5.
> 
> Can this operation be done in Grass with vector files?
> If not but you are bith an ArcInfo and Grass user, could this
> operation be done with AI?
------------------------------------------------------------------------
Rick Thompson-   Research Specialist          E-mail: rick at cast.uark.edu
Center for Advanced Spatial Technologies      Telephone: (501) 575-6159
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