[QGIS-Developer] GetFeatureInfo: sensitivity on rendered geometry vs original geometry.

[René-Luc Dhont]

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
>
>
> _______________________________________________
> QGIS-Developer mailing list
> QGIS-Developer at lists.osgeo.org
> List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer
> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-developer

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/qgis-developer/attachments/20190412/a7ce05a4/attachment.html>