[QGIS-Developer] QGIS not respecting WMTS cap tilematrixset

[Bakker, Anton]

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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