[GRASS-user] Points in a vector-map

[stn]

2010/7/1 Daniel Victoria <daniel.victoria at gmail.com>

> Or how about converting the polygons to raster and then run v.what.rast to
> add a collumn with the polycon categorie value? Or even better, v.what.vect?
>
> Or did I misunderstand the question?
>

Hi Daniel, hi Markus,

v.what.vector was the solution. Thank you.

I had been looking in completely the wrong place.

Previously I had successfully overlayed two vector maps and got all the
intersecting polygons with all the attributes of both maps. Also somewhere I
read that points are no longer treated as sites but also as vectors.

I concluded that points (imported with v.in.ascii) with attributes could
also be overlayed with a vector map, resulting in a new map with the points
having the attributes of the original points and all the attributes of the
polygon in which they fall. That does not work (why not?). v.overlay simply
returns the original polygons with existing but empty columns for the
attributes of the points. It does not report any kind of error in the
process.

So I tried to find a way to get v.overlay to work with points and never
considered other solutions.

Thanks again,
stn


>
> Daniel
>
> On Wed, Jun 30, 2010 at 6:31 PM, Markus Neteler <neteler at osgeo.org> wrote:
> > On Tue, Jun 29, 2010 at 9:25 AM, stn <stneumann at web.de> wrote:
> >> Hi,
> >>
> >> how can I identify which point lies in which polygon?
> >>
> >> The points are in an ascii-table, each with latitude, longitude and some
> >> other attributes like name, altitude and id-number.
> >> The vector-map is a map with political boundaries found in the
> vmap0-dataset
> >> at http://www.gdf-hannover.de/gis.php?id=5
> >
> > I don't know an elegant solution to this but you may
> > create the list of polygon categories with v.categories and print method,
> > then loop over the polygons to run v.extract + v.select on each
> > extracted polygon.
> >
> > Likely there are better solutions!
> >
> > Markus
> > _______________________________________________
> > grass-user mailing list
> > grass-user at lists.osgeo.org
> > http://lists.osgeo.org/mailman/listinfo/grass-user
> >
>
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