[QGIS-Developer] QGIS server issue: bounding box issues

[Bernhard Ströbl]

Hi Andreas,

remember ticket #9160 [1], probably the solution found there could be 
used for QGIS-Server?

Bernhard

[1] https://issues.qgis.org/issues/9160

Am 09.05.2019 um 11:28 schrieb Andreas Neumann:
> Hi QGIS (server) devs,
> 
> We came across issues around calculating bounding boxes in QGIS server.
> 
> 1. Layers with only one point feature:
> 
> If a layer contains only one single point feature, QGIS server 
> calculates a bounding box where the minx equals maxx and miny equals 
> maxy, so resulting in a bounding box without a width and height. Sounds 
> logical to QGIS server developers, but combined with the fact that QGIS 
> server doesn't take into account rendered symbol sizes (another issue we 
> have, see issue nr 2), it means that no WMS client will ever see this 
> one single symbol rendered, which can't be the solution here ...
> 
> 2. Layer bounding boxes do not take into account rendered symbol sizes:
> 
> Please have a look at 
> http://www.carto.net/neumann/temp/qgis_server_bounding_box_issue.png - 
> The green rectangle and the green arrows are not part of the QGIS server 
> rendering, but they are added as an annotation to the rendered QGIS 
> server graphics, to highlight the issues.
> 
> Here we have the issue that QGIS server only uses the "raw" geometry of 
> point symbols without taking into account rendered symbol sizes. Now, I 
> do understand that calculating symbol sizes is scale dependent and there 
> is no single solution to that, but again, I think the current behavior 
> of QGIS server (simply cutting off symbols at layer bounding boxes) is 
> not a good and nice behavior. At least, I think the author of the WMS 
> service should have a chance to define an extra margin to be added to 
> the bounding boxes of the raw geometries of the point layer, either as a 
> "per project" or "per layer" QGIS server configuration.
> 
> @Andrea: I wonder what Geoserver does in such cases?
> 
> Any thoughts how to solve these issues? The current behavior of QGIS 
> server is not satisfactory to me, for both cases.
> 
> Thanks for your replies,
> 
> Andreas
> 
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-- 
Bernhard Ströbl
Anwendungsbetreuer GIS

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