Hi all,
I submitted an issue (https://github.com/qgis/QGIS/issues/45460) on the issue
tracker which is about QGIS not respecting the WMTS capabilities tilematrixset.
@gioman On Github suggested to write to the mailing list. Considering it is a
usability issue the developers mailing list seemed appropriate.
I do not think the current behaviour of QGIS is necessarily a bug, it might
work as intended. But it does not match my expectation of how it ideally
should work.
So the issue I ran into is the following:
I have a WMTS which only serves tiles for specific zoomlevels. So in the WMTS
capabilities document we have a tilematrixset that starts from zoomlevel 05
(zoomlevels/tilematrices 00 - 04 are omitted), see the github issue for the
full capabilities document to reproduce:
<TileMatrixSet>
<ows:Identifier>EPSG:28992</ows:Identifier>
<ows:SupportedCRS>urn:ogc:def:crs:EPSG::28992</ows:SupportedCRS>
<TileMatrix>
<ows:Identifier>05</ows:Identifier>
<ScaleDenominator>384000.0</ScaleDenominator>
<TopLeftCorner>-285401.92 903401.92</TopLeftCorner>
<TileWidth>256</TileWidth>
<TileHeight>256</TileHeight>
<MatrixWidth>32</MatrixWidth>
<MatrixHeight>32</MatrixHeight>
</TileMatrix>
<TileMatrix>
<ows:Identifier>06</ows:Identifier>
When adding this WMTS to the map in QGIS, QGIS zooms to the bounding box
advertised in the capabilities (which corresponds to the extent of the
Netherlands, and z0 in the Dutch national tiling scheme) and starts immediately
loading tiles from the first available zoom level.
While I would expect QGIS to respect the service capabilities by default and
only show tiles starting from the scale of the first available zoomlevel (which
in this case is z05 which corresponds to a scale of 1:384000).
https://imgur.com/a/d31pEgU
My expectation is somewhat biased, since as a servicerpovider I would like to
be in control of how our services are rendered in QGIS. The current situation
does not allow for this, therefore I would like to propose the following :
QGIS by default respects the visibility of the WMTS layer as defined by the
available tilematrixsets in the cap doc (I suppose this should be the case for
all tiled resources, that make use of tilematrixsets). There are options on
these layers to override this behaviour for both
- Lowerbound zoomlevels, configure from what zoomlevel tiles will be
"underzoomed"
- Upperbound zoomlevels, configure till what zoomlevel tilles will be
"overzoomed"
So I am curious what the community thinks, looking forward to the discussion.
Met vriendelijke groet,
Anton Bakker
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