[Gdal-dev] OGR Performance Intersection, Union

[Frank Warmerdam]

Jean Michel PIERRET wrote:
> Hi,
>     I have a problem with the performance of OGR (Intersection, Union, ...),
> it seem to be slower than the library GPC (Generic Polygon Clipper) which i
> used before.     
> 
> Is it normal ?
> Do you have solutions or answers ?

Jean-michel,

I don't use GPC though I have heard good things about it.  Operations like
Intersection and Union in OGR are implemented by turning all geometries into
GEOS geometries, and then invoking GEOS functions.  The translation adds
some overhead, and I believe that some operations in GEOS are slower than they
may strictly need to be.   It is unclear whether this is an optimization
opportunity or just different tradeoffs being made on performance vs.
robustness.

In short, I think the issue lays in GEOS but I have no useful suggestions.

Best regards,
-- 
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