[GRASS-dev] v.in.ogr: islands not recognized

Wed Feb 11 12:47:05 PST 2015

On Wed, Feb 11, 2015 at 9:34 PM, Markus Neteler <neteler at osgeo.org> wrote:
> HI,
>
> I tried to import the NUTS3 map(s) from EU which leads to some obscur
> warnings (see below). While most can be solved with a "mild" snapping,
> still four islands are reported as an error. They are Andorra, etc and
> apparently really valid. The error message though suggests that the
> import was not successful. Could this be fixed?

This might have been fixed already in trunk, please test!

Markus M

>
> # Download NUTS3 2010, 3M and 10M
> # http://ec.europa.eu/eurostat/web/gisco/geodata/reference-data/administrative-units-statistical-units
>
> # create new location from SHP file
> grass70 -c NUTS_BN_03M_2010.shp ~/grassdata/eu_etrs89
> g.proj -w
>
> # import NUTS3 polygons (performs topology check)
> v.in.ogr input=NUTS_RG_03M_2010.shp output=NUTS_RG_03M_00
> ...
> Cleaning polygons
> -----------------------------------------------------
> Breaking polygons...
> ...
> -----------------------------------------------------
> Building areas...
> WARNING: Area of size = 0.0 ignored
> WARNING: Area of size = 0.0 ignored
> WARNING: Area of size = 0.0 ignored
> WARNING: Area of size = 0.0 ignored
> ...
> WARNING: Area of size = 0.0 ignored
> WARNING: Area of size = 0.0 ignored
>  100%
> 16926 areas built
> 1325 isles built
> Number of nodes: 113763
> Number of primitives: 355557
> Number of points: 0
> Number of lines: 0
> Number of boundaries: 355557
> Number of centroids: 0
> Number of areas: 16926
> Number of isles: 1325
> WARNING: Number of incorrect boundaries: 157
> -----------------------------------------------------
> Removing bridges...
>  100%
> -----------------------------------------------------
> Registering primitives...
> 48083 primitives registered
> 343316 vertices registered
> Building areas...
> WARNING: Area of size = 0.0 ignored
> WARNING: Area of size = 0.0 ignored
> WARNING: Area of size = 0.0 ignored
> ...
> WARNING: Area of size = 0.0 ignored
> WARNING: Area of size = 0.0 ignored
>  100%
> 16925 areas built
> 1335 isles built
> Attaching islands...
>  100%
> Number of nodes: 32451
> Number of primitives: 48083
> Number of points: 0
> Number of lines: 0
> Number of boundaries: 48083
> Number of centroids: 0
> Number of areas: 16925
> Number of isles: 1335
> WARNING: Number of incorrect boundaries: 36
> WARNING: Vect_get_point_in_poly_isl(): collapsed area
> WARNING: Unable to calculate area centroid
> WARNING: Vect_get_point_in_poly_isl(): collapsed area
> WARNING: Unable to calculate area centroid
> WARNING: Vect_get_point_in_poly_isl(): collapsed area
> WARNING: Unable to calculate area centroid
> WARNING: Vect_get_point_in_poly_isl(): collapsed area
> ...
> WARNING: Unable to calculate area centroid
> WARNING: Vect_get_point_in_poly_isl(): collapsed area
> WARNING: Unable to calculate area centroid
> -----------------------------------------------------
> Finding centroids for OGR layer <NUTS_RG_03M_2010>...
>  100%
> -----------------------------------------------------
> Writing centroids...
>  100%
> WARNING: 9912 areas represent more (overlapping) features, because polygons
>          overlap in input layer(s). Such areas are linked to more than 1
>          row in attribute table. The number of features for those areas is
>          stored as category in layer 2
> -----------------------------------------------------
> 7007 input polygons
> Total area: 5.75852E+12 (16925 areas)
> Overlapping area: 5.74784E+12 (9912 areas)
> Area without category: 5.32057E+08 (19 areas)
> -----------------------------------------------------
> Copying features...
>  100%
> Building topology for vector map <NUTS_RG_03M_2010 at PERMANENT>...
> Registering primitives...
> 59076 primitives registered
> 354309 vertices registered
> Building areas...
> WARNING: Area of size = 0.0 ignored
> WARNING: Area of size = 0.0 ignored
> WARNING: Area of size = 0.0 ignored
> ...
> WARNING: Area of size = 0.0 ignored
> WARNING: Area of size = 0.0 ignored
>  100%
> 16925 areas built
> 1335 isles built
> Attaching islands...
>  100%
> Attaching centroids...
>  100%
> Number of nodes: 32451
> Number of primitives: 59076
> Number of points: 0
> Number of lines: 0
> Number of boundaries: 48083
> Number of centroids: 10993
> Number of areas: 16925
> Number of isles: 1335
> WARNING: Number of incorrect boundaries: 36
> -----------------------------------------------------
> WARNING: Errors were encountered during the import
> Estimated range of snapping threshold: [1e-13, 1e-05]
> Try to import again, snapping with at least 1e-13: 'snap=1e-13'
>
> # --> the "WARNING: Vect_get_point_in_poly_isl(): collapsed area"
> looks like a debug message to an average user.
>
>
>
> # NEW ATTEMPT WITH SNAPPING
> GRASS 7.0.0svn (eu_etrs89): > v.in.ogr input=NUTS_RG_03M_2010.shp
> output=NUTS_RG_03M_2010 snap=1e-8 --o
> ...
> Writing centroids...
>  100%
> WARNING: 2748 areas represent more (overlapping) features, because polygons
>          overlap in input layer(s). Such areas are linked to more than 1
>          row in attribute table. The number of features for those areas is
>          stored as category in layer 2
> -----------------------------------------------------
> 7007 input polygons
> Total area: 5.75852E+12 (2759 areas)
> Overlapping area: 5.74784E+12 (2748 areas)
> Area without category: 5.32057E+08 (4 areas)
> -----------------------------------------------------
> Copying features...
>  100%
> Building topology for vector map <NUTS_RG_03M_2010 at PERMANENT>...
> Registering primitives...
> 8419 primitives registered
> 217332 vertices registered
> Building areas...
>  100%
> 2759 areas built
> 1315 isles built
> Attaching islands...
>  100%
> Attaching centroids...
>  100%
> Number of nodes: 4220
> Number of primitives: 8419
> Number of points: 0
> Number of lines: 0
> Number of boundaries: 5664
> Number of centroids: 2755
> Number of areas: 2759
> Number of isles: 1315
> -----------------------------------------------------
> WARNING: Errors were encountered during the import
> Estimated range of snapping threshold: [1e-13, 1e-05]
> Try to import again, snapping with 1e-07: 'snap=1e-07'
>
> v.build NUTS_RG_03M_2010 error=NUTS_RG_03M_2010_errors
> ...
> Number of nodes: 4
> Number of primitives: 4
> Number of points: 0
> Number of lines: 0
> Number of boundaries: 4
> Number of centroids: 0
> Number of areas: 4
> Number of isles: 4
>
> The "WARNING: Errors were encountered during the import" is scary
> while it seems to be valid islands (Andorra, San Marino, two islands
> near Rome).
>
> thanks
> Markus
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