vectors: lines to polygons

Yes, because with Grass, a single line can be used for 2 areas,one >on each side.
Once you change the 'L' to 'A' in your ascii vector file,
run v.in.ascii to made a binary vector file and then run
v.support, which will compute the topology, hence creatingyour areas >().
You will then need to give each area a label with v.digit,
unless you have a site file giving you a point location
(with the number you will use for polygon attribute) inside
each area to be labelled, in which case you can create a
dig_att file before running v.support.

Labelizing all the areas doesn't help. It seems to me that it doesn't works because v.support's algorithm is not able to recognize the polygons contained in the map.

Juan

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Juan BaƱuls wrote:

Labelizing all the areas doesn't help. It seems to me that it doesn't works
because v.support's algorithm is not able to recognize the polygons
contained in the map.

When v.support doesn't recognize polygons, it is generaly because
you have some lines that doesn't connect in your file. With v.support,
you can identify polygons not closed or lines not connected.

It appears also that if you have a *very* little line alone, th polygon
cannot be closed :

BAAAAAAAAAAAAAAAD
B CD
B C D
  BBBBBBBBB D
           BBBDDD

The line marked 'C' must be either deleted, either changed in 'L' type
(only 'A' type line are used for polygon topology)

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