[postgis-users] problems cleaning geometry - other options?

[Kevin Neufeld]

Have you tried updating the geometry with a new polygonized polygon 
constructed from the linework?

UPDATE swbd
SET wkb_geometry = ST_BuildArea(ST_Boundary(wkb_geometry))
WHERE cell = 145018 AND wb = 353;

Cheers,
-- Kevin

William Kyngesburye wrote:
> I'm trying to fix some polygons-with-holes imported from shapefiles 
> where the main polygon is not the first in the list, one of the hole 
> polygons is, making them invalid.
>
> These are 3D multipolygons - imported from the SRTM SWBD shapefiles 
> (with GDAL). (file w162n55n if anyone wants to try)
>
> The cleanGeometry funtion at:
>
> http://postgis.refractions.net/support/wiki/index.php?CleanPolygons
>
> isn't working, I get an error:
>
> =>select astext(cleangeometry(wkb_geometry)) from swbd where cell = 
> 145018 and wb = 353;
> NOTICE:  Hole lies outside shell at or near point -161.201 55.9992 0
> CONTEXT:  PL/pgSQL function "cleangeometry" line 15 at IF
> ERROR:  Dimensions mismatch in lwcurve
> CONTEXT:  PL/pgSQL function "cleangeometry" line 19 at assignment
>
> I tried forcing the geometry to 2D (st_force_2d()) and I get a 
> different error:
>
> NOTICE:  Hole lies outside shell at or near point -161.201 55.9992
> CONTEXT:  PL/pgSQL function "cleangeometry" line 15 at IF
> ERROR:  Exception in LWGEOM2GEOS: curved geometry not supported.
> CONTEXT:  PL/pgSQL function "cleangeometry" line 19 at assignment
>
> These shapefiles don't have curved geometry (I'm not sure it's 
> supported in shapefiles).
>
>
> I wonder if there is a simpler operation that could reorder 
> sub-polygons to put the one that contains all the others first?  And 
> would it be faster or slower?
>
> -----
> William Kyngesburye <kyngchaos*at*kyngchaos*dot*com>
> http://www.kyngchaos.com/
>
> "History is an illusion caused by the passage of time, and time is an 
> illusion caused by the passage of history."
>
> - Hitchhiker's Guide to the Galaxy
>
>
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