[Qgis-developer] QgsGeometry, Geos and SFCGAL

[G. Allegri]

Thanks Sebastiaan for raising this point. It's clear that if (SF)CGAL was
somehow introduced inside the core it would need maintanance.

Nyall, I agree with you. CGAL shouldn't overlap GEOS, even if its
robustness (infinite precision) can make the difference.
The real benefits would arise if/when QGIS will want to widen its SQL/MM
geometries. TINs, polyhedral surfaces, or simply 3D predicates considering
the z coordinate in 2.5D geoms.
I fear GEOS will hardly expand to 3D, therefore CGAL could be the right
candidate to fill the missing parts.

Giovanni

Il 12 mar 2017 00:07, "Sebastiaan Couwenberg" <sebastic at xs4all.nl> ha
scritto:

> On 03/11/2017 04:26 AM, Nyall Dawson wrote:
> > Instead, a better approach is if we selectively change certain
> > operations to use a different backend only after we carefully evaluate
> > the results for each individual operation concerned. E.g. if we found
> > that SFCGAL resulted in intersections which are equally reliable as
> > GEOS, and faster in the majority of geometries, then we'd change
> > QgsGeometry::intersection to ALWAYS use SFCGAL.
>
> SFCGAL is not very actively developed, in its current shape is not the
> best choice to build upon. It either needs more active participation
> from the community, or better funding. Since the initial funding dried
> up, the activity in the project slowed to a crawl.
>
> I'm considering removing the SFCGAL support in the PostGIS Debian
> package if the situation doesn't improve. For the same reasons I'd be
> reluctant to enable its support in QGIS if that were to arrive.
>
> Kind Regards,
>
> Bas
>
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