[Qgis-user] Editing polygons

[Kai-Christian Bruhn]

Hi,

your problem is the topology of the polygon. Your data are known as 
spaghetti-data, i.e. each area needs a complete polygon, "shared" 
boundaries are two linestrings.

Best way would be to get into grass. After importing your data into the 
GRASS database, you will have benefit of full topology.

Make your edits within GRASS and later export the data back into e.g. 
shapefile.

Lot's of documentation on handling vectordata within GRASS is available 
in different web-ressources. Just search for GRASS vector import edit

Best

Kai

Am 27.06.2011 16:32, schrieb Laura Guillot:
> I'm trying to reshape polygons of a lancover map, in order to make them
> to be more
> coincident with an overlaid raster image (orthophoto 1:5M).
> If I just move the nodes to the correct position, I create a correct
> line but leave a hole behind: the other
> polygon keeps its line where it was. See a pict here:
> https://sites.google.com/site/lguillotdummy/home/boundaryproblem.jpeg
>
>   Is there any way I could just move the lines as boundaries?
>
> I've tried by converting poygons to lines first, but the problem is very
> much the same: it seems like
> there is always a double line, one for each adjacent polygon.
>
> A possible solution would be having the lines automatically cut into
> segments, each going from one vertex to another.
> And having just one segment for each boundary. Is that possible? Is
> there a process to cut into segments after running polygons to lines?
>
> Or perhaps there is a cmpletely different way to accomplish the same
> goal: modifying the boundaries between polygons.
>
> Thanks!
>
> L
>
>
>
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