[GRASS-user] center line with v.generalize ?

[John C. Tull]

Another possibility, perhaps, would be to export the raster result of  
v.to.rast and do some editing in an image application, like the Gimp.  
You can try to isolate the river from the other raster information and  
save that, then re-import to grass, r.to.vect, etc.

There may be a way to work on an exported version of the vector in  
something like Inkscape. I've not tried any of this myself, so perhaps  
someone else has some comments on how or whether this will work.

John


On Jan 24, 2008, at 6:10 AM, Gabriele N. wrote:
> Maris Nartiss-2 wrote:
>>
>> Just a quick idea - if vector map contains only rivers, You could try
>> out v.to.rast and then r.thin till You get something similar to river
>> and then convert back to vectors with r.to.vect.
>>
>> Report, if it works.
>>
>> Maris.
>>
>>
> I have already tried with r.thin etc. .. but sometimes I need a  
> little too
> pixels (because the rivers is very narrow and contorted) to avoid  
> errors of
> approximation.
> The problem is that choosing a region with high resolution happens '  
> out of
> memory error '.
>
> Thanks