[gdal-dev] setting a spatial filter on a postgis layer gives wrong results

[jratike80]

Hi,

It should be already possible to make accurate filtering from PostGIS by
executing SQL with ST_Intersects.

-Jukka Rahkonen-


Even Rouault-2 wrote
> On vendredi 5 juillet 2019 10:12:41 CEST Landry Breuil wrote:
>> Hi,
>> 
>> initially saw this with gdal 2.2.3 on debian, and confirmed the
>> behaviour is the same with gdal 3.0 on openbsd.
>> 
>> I'm doing a spatial join between an union of geometries filtered from a
>> geopackage and a tileindex layer stored in postgis, and the spatial
>> filter set on the postgis layer behaves weird, the provided result is as
>> if the bbox of the spatial filter/geometry was used, instead of the
>> filter itself.
> 
> This indeed exactly this. The PG driver implements spatial filtering only 
> based on the envelope of the filter geometry, whereas the MEM driver uses
> the 
> full geometry
> 
> Quoting
> https://gdal.org/api/
> ogrlayer_cpp.html#_CPPv4N8OGRLayer16SetSpatialFilterEP11OGRGeometry
> """
> Currently this test is may be inaccurately implemented, but it is
> guaranteed 
> that all features whose envelope (as returned by
> OGRGeometry::getEnvelope()) 
> overlaps the envelope of the spatial filter will be returned. This can
> result 
> in more shapes being returned that should strictly be the case.
> """
> 
> I guess the PG driver should be fixed. This is probably just an historical 
> artifact.
> 
> Even
> 
> -- 
> Spatialys - Geospatial professional services
> http://www.spatialys.com
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