[GRASS-user] Vectorise a raster file

[Jachym Cepicky]

Hi,

On Sat, May 13, 2006 at 03:18:59PM +0200, Yves Jacolin wrote:
> Hi,
> I created a raster with the visiblity function, and I wanted to vectorise it. 
> I used v.to.vect but the result it is not good because there are holes in 

did you mean 
    
    r.to.vect ?

    r.null map=los null=0
    r.mapcalc los="if(los)"
    r.to.vect in=los out=los feature=area
    v.out.ogr in=los dsn=los olayer=los type=area
    
     
> area that are fill by color (and have to be empty). I try to use mapcalc to 
> remove all bad area, i try to remove it by db.execute but, if I list value, I 
> have for all item value=1 but if I try to display the vector using this sql 
> statement : value=1, the vector is correctly displaying ! If I export it in 
> shp the vector is not correct !
> 
> To explain the problem, I try to calculate area where we can connect to a wifi 
> ADSL connection. using aerial datas and SRTM90 usign r.los function.
> If the elevation is upper than the aerial, signal is stoped ! So I have to get 
> holes in area (My location is somewhere in the French alpes).
> 
> If you have an idea ...
> 
> Y. 
>  
> Yves Jacolin
> -------------
> http://yjacolin.gloobe.org
> http://softlibre.gloobe.org
> 
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Jachym Cepicky
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