polygons
Trond Rinde
trinde at donau.boku.ac.at
Fri Jul 1 18:29:57 EDT 1994
Hello!
I have delineated polygon boundaries from a scanned image and imported
it into a raster map layer in grass. Then, after using "r.thin" on the
boundary lines, I converted the polygons to a vector layer using
"r.line" with option "type=area". All that worked fine, and I got a map
layer with 363 lines, 263 nodes, 118 areas and 8 isles. Now, from these
polygons I want to create a raster map where all the cells within a
polygon has a certain category value. The result should be a patchy mosaic
of polygons with different colors. To achieve this I use "v.support" on the
converted vector-map to create topology and to assign categories to the
polygons. Then I use "v.to.rast" to re-convert the polygons from vector to
raster format.
I am obviously doing something wrong, because all I get is an empty raster
layer. My region is not changed during the process, neither is the resolution
and I believe I did assign category labels to the polygons (like it is
said in the manual) when I ran "v.support".
If anyone see the problem I would appreciate some hints.
Trond Rinde
--
=====================================================================
Siv.ing. Trond Rinde
Institut f. Wasserwirtschaft, Hydrologie und konstruktiven Wasserbau
Universitet f. Bodenkultur
A-1190 Wien, Nussdorfer Laende 11
tel: 1 36 92 924 352
fax: 1 36 92 924 350
email: trinde at donau.boku.ac.at
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