Ah, 
I do not think there is anything alternative.
I will be careful if you solve this problem.
However thanks
Gabriele
On 24.01.2008 14:03, Gabriele N. wrote:
> I would locate the midline of the river.
> So I would like to transform the polygon with the middle line.
>Ah now I get it. Unfortunately v.generalize doesn't support merging
(yet). Also I don't have time to work on that at the moment. Daniel
would you have time to implement this?--Wolf
--
<:3 )---- Wolf Bergenheim ----( 8:>
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.
2008/1/24, Gabriele Nolè <gis.gn@libero.it>:
Ah,I do not think there is anything alternative.
I will be careful if you solve this problem.
However thanksGabriele
> On 24.01.2008 14:03, Gabriele N. wrote:
> > I would locate the midline of the river.
> > So I would like to transform the polygon with the middle line.
> >
>
> Ah now I get it. Unfortunately v.generalize doesn't support merging
> (yet). Also I don't have time to work on that at the moment. Daniel
> would you have time to implement this?
>
> --Wolf
>
> --
>
> <:3 )---- Wolf Bergenheim ----( 8:>
>
>_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user
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.
2008/1/24, Gabriele Nolè <gis.gn@libero.it>:
Ah,I do not think there is anything alternative.
I will be careful if you solve this problem.
However thanksGabriele
> On 24.01.2008 14:03, Gabriele N. wrote:
> > I would locate the midline of the river.
> > So I would like to transform the polygon with the middle line.
> >
>
> Ah now I get it. Unfortunately v.generalize doesn't support merging
> (yet). Also I don't have time to work on that at the moment. Daniel
> would you have time to implement this?
>
> --Wolf
>
> --
>
> <:3 )---- Wolf Bergenheim ----( 8:>
>
>_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user
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
--
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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