[GRASS-user] v.generalize failing on some geoms

Markus Metz markus.metz.giswork at gmail.com
Sat Feb 10 13:53:29 PST 2018


On Fri, Feb 9, 2018 at 6:19 PM, Paolo Cavallini <cavallini at faunalia.it>
wrote:
>
> Hi all,
> v.generalize is failing to simplify some of my geometries when in
> EPSG:3857. Same geoms in EPSG:3003 were simplified correctly.
> Incorrect borders were reported, unclear to me why.
> All the best, and thanks for any hint.

This seems to be a reprojection problem.

If you reprojected the vector data in GRASS with v.in.ogr + v.proj, this is
a problem of GRASS, granted that v.in.ogr did not complain about vector
topology.

If you reprojected non-topological polygons, this is a common problem when
reprojecting non-topological polygons. Please import these polygons first
into GRASS, then reproject within GRASS and run v.generalize on the
reprojected GRASS vector.

HTH,

Markus M
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