[GRASS-user] convert vector line topology to area topology

[Nicolas Devaux]

Hi, I start to use Grass, and I'm wondering if I'm not doing wrong, 
trying to apply ArcInfo 7 concepts to Grass vector topology.

Is it possible to change a vector line topology map to a new vector area 
topology map?

I explain : I imported a raster map showing fields boundaries. I want to 
convert this map into vector information showing fields as areas. Before 
doing that, I would like to work on line geometry in order to enhance 
final quality information (close interrupted boundaries, erase dangle 
nodes...).
I use r.to.vect with line option and do all cleaning operations needed. 
But after all I can't reach area topology (using v.build or v.clean). If 
I use at the beginning r.to.vect with area option, unclosed fields 
boundaries are not converted....
With Arcinfo, I used to import at first line information, and it was 
possible after to reach polygon topology using "build polygon" command. 
How can I manage the same problem with Grass?

Thanks for any help