[GRASSLIST:799] Automatic creation of Areas (polygons) from connected lines

GRASS GRASS user
1

Hello,

I suspect the question has already been asked, but I didn't
find an obvious answer.

Given a vector file with a correct topology (all lines are
connected and broken at nodes) is there a "magic" modules
allowing the creation of areas (parcels) from this vector
file? [to go the raster way is not an option here due to the
precision and hence the size of the resulting file]

Thanks for the help!

2

tlaronde@polynum.org said:

Hello,

I suspect the question has already been asked, but I didn't
find an obvious answer.

Given a vector file with a correct topology (all lines are
connected and broken at nodes) is there a "magic" modules
allowing the creation of areas (parcels) from this vector
file? [to go the raster way is not an option here due to the
precision and hence the size of the resulting file]

Could you please be a bit more specific:

- in what format is you correct vector file ?
- does this file contain lines and you want to transform them into areas ?

- If your file is in GRASS format and contains lines that you wish to
transform into areas, you can try v.line2area.

Moritz

3

En réponse à Moritz Lennert <mlennert@club.worldonline.be>:

tlaronde@polynum.org said:
> Hello,
>
> I suspect the question has already been asked, but I didn't
> find an obvious answer.
>
> Given a vector file with a correct topology (all lines are
> connected and broken at nodes) is there a "magic" modules
> allowing the creation of areas (parcels) from this vector
> file? [to go the raster way is not an option here due to the
> precision and hence the size of the resulting file]

Could you please be a bit more specific:

- in what format is you correct vector file ?
- does this file contain lines and you want to transform them into areas
?

- If your file is in GRASS format and contains lines that you wish to
transform into areas, you can try v.line2area.

Thanks for the reply. Eventually I already found the answer in a message :

(this is GRASS vector format)
v.line2area
v.alabel

do the job perfectly.

BTW, I suggest for newcomers like me to emplasize in the doc the fact that
GRASS is a topology engine able to build aread from edges : no need to import
CAD shapes and so on (that has mistaken me at the begining).