[GRASS-user] Number of centroids outside area: difficulty with cleaning
markus.metz.giswork at gmail.com
Sun Apr 14 04:06:02 PDT 2013
On Sun, Apr 14, 2013 at 11:02 AM, RichardC <richtcooper at hotmail.com> wrote:
> I'm trying to remove a 'Number of centroids outside area' after
> re-projecting a file.
> I've tried v.clean with various tools. including breaklines/boundaries,
> break polygons, snap lines/boundaries.
> The intial imported shapefile did not display any errors, but the following
> errors appeared on re-projecting the latter file:
> Building topology for vector map <as_bas_shp>...
> Registering primitives...
> 44546 primitives registered
> 1680359 vertices registered
> Building areas...
> 13602 areas built
> 2828 isles built
> Attaching islands...
> Attaching centroids...
> Number of nodes: 33748
> Number of primitives: 44546
> Number of points: 0
> Number of lines: 0
> Number of boundaries: 30931
> Number of centroids: 13615
> Number of areas: 13602
> Number of isles: 2828
> *Number of centroids outside area: 13
> Number of duplicate centroids: 108
> Number of areas without centroid: 108*
> I can remove the duplicate centroids with v.clean (using bpol) but not the
> centroids outside area.
> What would be the easiest way to remove, or at least to identify (filter
> for) and manually assess?
The reason for these problems is one step earlier. Try to densify the
vector boundaries with v.split, optionally followed by
v.build.polylines before reprojecting it. See  for an example of
the effect on reprojection.
> I've also tried outputting the errors using the error= command, but no
> geometries are visible in the latter.
> View this message in context: http://osgeo-org.1560.x6.nabble.com/Number-of-centroids-outside-area-difficulty-with-cleaning-tp5046717.html
> Sent from the Grass - Users mailing list archive at Nabble.com.
> grass-user mailing list
> grass-user at lists.osgeo.org
More information about the grass-user