[Gdal-dev] exportToGEOS performance

[Frank Warmerdam]

On 10/6/05, Pirmin Kalberer <sp_ml at sourcepole.com> wrote:
> Hi,
>
> I'm using the GEOS polygonizer for the OGR Interlis driver. But the
> polygonization is quite slow because of the exportToGEOS call. The code looks
> like this:
>
>     geos::Geometry *poThisGeosGeom = poLines->exportToGEOS(); //slow
>     geos::Polygonizer* polygonizer = new geos::Polygonizer();
>     polygonizer->add(poThisGeosGeom);
>     vector<geos::Polygon*> *poOtherGeosGeom = polygonizer->getPolygons();
>
> We're talking about exporting 1677 OGRLineString's in about 1'20'' and
> polygonizing them within a few second.

Pirmin,

I was planning to rewrite exportToGEOS() to translate using WKB
format instead of WKT which I suspect will be significantly faster.
This will be part of an upgrade to use the GEOS C API in time for
the next release.  In the meantime, you might want to try modifying
your local copy to go via WKB instead of WKT.  I think when I
first looked at GEOS only the WKT conversion was supported.

Best regards,
--
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