Hi Andreas,
I think QGIS Server has to use the rendered geometries to identify Feature.
Is it possible to get the point layer to polygon rendred layer ?
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
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