[qgis-qwc2] Issue publishing Arctic project in EPSG:3996 with QWC2 (CRS not defined & anti-meridian splitting)

[Sandro Mani]

Hi


You can register custom projections in the config.json -> projections block.


Hope this helps

Sandro



On 24.12.25 04:39, 김용운 빙하지권연구본부 via qgis-qwc2 wrote:
>
>
>
> Hello,
>
> I am working on publishing a QGIS project to QWC2 in order to share 
> Arctic Ocean datasets in a web environment.
>
> Because my datasets are located in the Arctic, I normally use 
> EPSG:3996 (WGS 84 / Polar Stereographic) as the project CRS in QGIS. 
> In desktop QGIS, this CRS works correctly and produces the expected 
> visualization (Figure 1).
>
> However, when publishing the project to QWC2, the theme fails to load 
> and QWC2 reports that “the projection EPSG:3996 is not defined” 
> (Figure 2). Due to this limitation, I changed the project CRS to 
> EPSG:3857 so that the project can be loaded in QWC2.
>
> With this workaround, I encounter serious rendering issues for 
> datasets crossing the 180° meridian (anti-meridian):
> - line and track features are split and rendered at both edges of the map,
> - and in some CRS combinations the geometries appear heavily distorted 
> (Figures 3 and 5).
>
> For reference, these are the main configurations I tested:
> - Desired QGIS desktop view:
>   Project CRS = EPSG:3996, Layer CRS = EPSG:4326 (Figure 1)
> - QWC2 workaround configuration:
>   Project CRS = EPSG:3857, Layer CRS = EPSG:3996 (Figure 3)
>
> I tried multiple CRS combinations, but this setup provided the closest 
> overall alignment in QWC2, although the anti-meridian splitting 
> problem remains. I also tested several approaches suggested in 
> documentation and online resources (e.g. tile-based basemaps, geometry 
> correction), but none resolved the underlying issue.
>
> Since many of my Arctic datasets cross the 180° meridian, this problem 
> affects a large portion of the data and prevents producing a visually 
> continuous map.
>
> Could you please advise on:
> - whether EPSG:3996 can be properly supported in QWC2, or
> - the recommended workflow for publishing Arctic (polar) data in QWC2 
> without visual discontinuities at the anti-meridian?
>
> Any guidance regarding CRS configuration, QGIS Server / QWC2 settings, 
> or preprocessing strategies would be greatly appreciated.
>
> Thank you very much for your help.
>
> Best regards,
>
>
>
> _______________________________________________
> qgis-qwc2 mailing list
> qgis-qwc2 at lists.osgeo.org
> https://lists.osgeo.org/mailman/listinfo/qgis-qwc2
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/qgis-qwc2/attachments/20251224/42c48d5a/attachment.htm>