Wow this is a hell of a comprehensive answer :) Thank you very much... My bad, I didn't even think about checking the validity of the geometries here. I will correct them and make further tests
Cheers Stéphane On 28 Jul 2017 9:39 p.m., "Giovanni Manghi" <[email protected]> wrote: > Hi, > > > > Hi all > > > > I have made a few tests of GDAL 2.2.0 on Ubuntu 16.04 with QGIS 2.14.14 > and > > have found out that most geoprocessing tools implying 2 layers (clip, > > difference, intersection, etc.) wrongly give empty geometries when the > data > > is in CRS EPSG:7694 (*Kyrg06-3*, newly added CRS to GDAL in 2.2.0). Same > > behavior with QGIS 2.18.11 with GDAL 1.11.3 > > > > For example, when using the Tool *Vector - Geoprocessing tools - > Difference* > > the difference between 2 layers gives an empty geometry. Using the same > > tool on the same data with the CRS 32643 (*WGS84 UTM43N*) gives correct > > results. > > > > I have communicated on the Ubuntugis mailing list and got the following > > feedback from Even Rouault: > > > > *I've run ogrinfo -al shp > log.txt on your dataset with GDAL 2.2 and > GDAL > > 2.1 and get almost the same results. The only difference is that GDAL 2.2 > > now reports the SRS of layers kyrgyzstan_UTM43N and rayons_UTM43N with an > > explicit EPSG:32643 code, which is an intended change of GDAL 2.2, and I > > wouldn't think that would cause issues to QGIS. So my feeling is that the > > issue is more with the processing tool itself, or a subtle issue in the > > integration of QGIS&GDAL.* > > > > Test dataset (in both CRS) here: http://www.henriod.info/share/shp.zip > > > > Is it something to be reported as a QGIS bug? Can you reproduce this > > behavior? > > > I made some test and here following a few notes: > > > 1) the geoprocressing tools in the "vector" menu are the native QGIS > ones, and I don't thinkthey make use of GDAL/OGR to make the > operations, on the other hand in the Processing toolbox you find also > a few ones (I have in mind since a long to add more) really based on > GDAL/OGR. > > > 2) I noticed that in your layers in EPSG:7694 there are geometries > errors that are not present in the EPSG:32643, and here lies the > problem of the wrong results you see, it does not depend on the CRS of > the inputs. > > > 3) I fixed the inputs geometry errors with my favorite tool, the > liblwgeom plugin for the Processing toolbox and its "MakeValid" tool > (equivalent to PostGIS's ST_MakeValid) and after that the operation > returned the expected results > > > 4) The geoprocessing OGR based tools are more verbose in their log and > so was easy to spot the geometry error messages > > > 5) the OGR based "clip by vector" tool returned also an output in > EPSG:7694 while the equivalent QGIS tool returned an output with 4326 > assigned CRS, but if you change it manually the result is there and in > the right place. > > > > hope this helps > > -- G -- > _______________________________________________ > QGIS-Developer mailing list > [email protected] > List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-developer
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