Hi Le jeu. 17 sept. 2020 à 11:31, Andreas Neumann <a.neum...@carto.net> a écrit :
> Hi Régis, > > Indeed interesting. > > Is there evidence that it will also be faster than previous versions? If > yes - for certain operations or generally faster? > Well not yet, and this will depend a lot on the type of features, vertex density and so on. I we trust some unit tests, and compare with ESRI on big datasets (France 4G antennas intersect with municipalities), we could expect something between twice and four times faster. That's a hope a that point not a measured fact. > We had issues in the past with the "Geometry checks" that you could define > on a layer (Layer Properties --> Digitizing settings) - tests about > overlays and gaps. It was always slow and not so reliable. Once you tried > to fix one error you would get even more errors through the fix and then > you would end up with even more errors when trying to fix the error ... > Hopefully, this will work better then ... > I think this should help indeep. Bye > Greetings, > > Andreas > > On 2020-09-17 09:33, Régis Haubourg wrote: > > Hi there, > I'm forwarding a call [0] from Paul Ramsey and the JTS-GEOS teams. > I've been following this closely for 3 years now and we have been > providing testing and test datasets to try to help here. > > > > In short, GEOS provides most of the geometry computations tools to PostGIS > QGIS & al. The intersection, difference etc.. (overlay operations) suffered > from using full numeric precision and lacked snapping and rounding > operations. > > Thus our libraries were slow, and prone to topology errors due to those > numeric precision issues. Most of us have seen intersections or union > operations failing from time to time. > > The new overlay operation implements snap rounding operations (which is > implemented in ESRI tools for instance) and will provide fast and robust > operations. > > Now it is available in the 3.9 branch of GEOS. > > As QGIS uses GEOS extensively in editing, displaying and algorithms, we > have to take a look seriously at the positive impacts and potential > regressions. > > Paul warns that they spotted no regression in Z handling, which probably > means the test coverage is very low in GEOS CI, and we might expect > regressions on the Z handling here, especially for snapping I bet. > > Anyhow this is GREAT news for the OSGEO community because this was one > major glass ceiling for us. We sometimes had no choice than switching to > GRASS topological operation to do some very basic operations. Hopefully > these times are gone :) > > And combined with subdividing features, we should gain a massive order of > magnitude in speed for overlay. > > Time to test this big win! > > Best regards > > Régis > > [0] > https://lists.osgeo.org/pipermail/geos-devel/2020-September/009670.html > > _______________________________________________ > QGIS-Developer mailing list > QGIS-Developer@lists.osgeo.org > List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-developer > > >
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