wrong WMTS GetTile requests for some WMTS servers

[keewis]

I'm trying to add tiles from this WMTS link to the terria instance at nationalmap.gov.au (share link)

While this allows me to see the list of available layers, adding a layer to the map does not actually display anything, and I see tile requests like

https://wmts.marine.copernicus.eu/teroWmts/NWSHELF_ANALYSISFORECAST_PHY_004_013/cmems_mod_nws_phy_anfc_0.027deg-3D_PT1H-m_202309?tilematrix=3&layer=NWSHELF_ANALYSISFORECAST_PHY_004_013/cmems_mod_nws_phy_anfc_0.027deg-3D_PT1H-m_202309/thetao&style=cmap:thermal&tilerow=2&tilecol=4&tilematrixset=EPSG:3857&format=image/png&service=WMTS&version=1.0.0&request=GetTile

failing with status code 400.

This server is a bit special in that in the response to GetCapabilities it requests using https://wmts.marine.copernicus.eu/teroWmts as the WMTS service endpoint for GetTile:

https://wmts.marine.copernicus.eu/teroWmts?tilematrix=3&layer=NWSHELF_ANALYSISFORECAST_PHY_004_013/cmems_mod_nws_phy_anfc_0.027deg-3D_PT1H-m_202309/thetao&style=cmap:thermal&tilerow=2&tilecol=4&tilematrixset=EPSG:3857&format=image/png&service=WMTS&version=1.0.0&request=GetTile

works as expected. However, this seems to be supported by the WMTS standard, as libraries like GDAL or owslib produce the right requests (I didn't read the standard text, though, so I may be wrong on that).

Would it be possible to fix that? I unfortunately don't know enough about JavaScript / TypeScript to open a PR myself.

cc @rsignell-usgs, @mdsumner

demonstration using the owslib.wmts python library

from owslib.wmts import WebMapTileService

url = "https://wmts.marine.copernicus.eu/teroWmts/NWSHELF_ANALYSISFORECAST_PHY_004_013/cmems_mod_nws_phy_anfc_0.027deg-3D_PT1H-m_202309?service=WMTS&request=GetCapabilities"

wmts = WebMapTileService(url)
response = wmts.gettile(
    layer="NWSHELF_ANALYSISFORECAST_PHY_004_013/cmems_mod_nws_phy_anfc_0.027deg-3D_PT1H-m_202309/thetao",
    tilematrixset="EPSG:3857",
    tilematrix="5",
    row=9,
    column=14,
    format="image/png",
)
print(response.geturl())
with open("test.png", mode="wb") as f:
    f.write(response.read())