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?Thanks!
Agus
What you can do is reclass the thematic image, in a way that you have
a map showing type 4 and a map showing type 5.
Then apply r.grow on one of the maps.
with r.mapcalc you can then extract lines that belong to both type 5
and type 5.
This is of course not as accurate as it has to be, because the lines
are shifted 1 cell towards the category that has not been "grown"
Ronald Wiemer
R.O.B. / Archis
Kerkstraat 1
NL 3811 CV Amersfoort
The Netherlands
Tel: ++ 31 33 4634233
Fax: ++ 31 33 4653235