On Fri, Apr 12, 2019 at 3:53 PM René-Luc Dhont <[email protected]> wrote:
> Hi Andreas, > > I think QGIS Server has to use the rendered geometries to identify Feature. > Hi René, Yeah, I also though that's the only solution, what scares me is the performances cost, because we would need to render and check each layer individually. > Is it possible to get the point layer to polygon rendred layer ? > I don't follow you, can you explain what's in your mind? > > Regards, > René-Luc > > Le 12/04/2019 à 15:43, Andreas Neumann a écrit : > > Hi, > > I'd like to discuss an issue with GetFeatureInfo that we have with point > symbols. > > (Point) symbols can have different sizes (sometimes rather large), > different anchor points and sometimes even with offset away from the > original feature geometry. Often, the rendering of the point symbol differs > substantially from the original point geometry. > > Now, our issue is that GetFeatureInfo often fails miserably in such cases. > People try to click on the visible symbol, which doesn't correspond to the > original geometry. > > One such example WMS: > > https://services.geo.zg.ch/ows/Abfallsammelstellen > > The symbols are rather large, but the anchor point is at the bottom of the > symbol. Users now think that they can click anywhere on the symbol, but in > fact they can only click on the original geometry at the very bottom of the > symbol, taking into account the FI_POINT_TOLERANCE parameter. > > Things get even worse when one wants to identify points that are displayed > using the point displacement renderer. There, GetFeatureInfo is only > sensitive on the center point, and not at all at the rendered points at a > completely different position. > > Now my question: could we improve QGIS server that GetFeatureInfo responds > to the bounding boxes of the rendered geometries (as opposed to the raw > geometries), taking into account sizes, offsets, etc. > > Would this be technically possible? > > Would others also think that this is useful to have? > > Or would this even contradict OGC standards? > > Do other WMS servers implement such behaviors (Geoserver, UMN)? > > Thanks for the discussion, > > Andreas > > _______________________________________________ > QGIS-Developer mailing [email protected] > List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-developer > > > _______________________________________________ > 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 -- Alessandro Pasotti w3: www.itopen.it
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