[GRASSLIST:5056] Re: vector lines to area?

[David Mahoney]

It sounds like you are trying to build "donut" areas, with an internal 
isle clipped out. The only way I have found so far to do this is to 
parse the output from v.build option=dump to identify the island 
polygons, update the attribute table with this information, and then 
run v.extract to select only the non-isle polygons. It would be nice if 
v.category had a option to not label holes in a larger polygon.

David

On Thursday, December 2, 2004, at 04:00 PM, Allard, Yannick (EXP) wrote:

> Hi everyone,
>
> I have a porblem concerning the transformation of lines into area. I 
> have .e00 files which I have converted with avcimport. These vector 
> files are only lines even if some of them should define an area (there 
> is no PAT in the e00 file, only AAT). I've tried importing the vector 
> lines as area boundaries but it dont work quite well, some area are 
> not showing up and some other that shouldn't be areas but holes are 
> created. Is there an easy way to transform those lines which are 
> defining an area into a real area so I could build a raster map with 
> these area showing up? I've tried v.digit and selecting an centroid. 
> However, for some area with holes the holes are still defined as areas 
> (if I import the lines as area boundaries) or the lines are not 
> defined as boundaries so I've got a centroid outside an area (is there 
> a way to change the line into a boundary other than v.type, using 
> v.type transform the lines as boundaries for 2 areas, which is not my 
> case).
>
> I'm using Grass 5.7.0
>
> Thanks in advance, best regards
>
> Yannick