[gdal-dev] WMTS "No zoom level found"

[Vautour, André (INT)]

> -----Original Message-----
> From: gdal-dev [mailto:gdal-dev-bounces at lists.osgeo.org] On Behalf Of
> hugfr
> Sent: Friday, May 5, 2017 12:10
> To: gdal-dev at lists.osgeo.org
> Subject: [gdal-dev] WMTS "No zoom level found"
> 
> Hello,
> 
> I try to create an xml file suitable for gdal wmts but I got this error "no zoom
> level found" (when I try a gdalinfo) and I don't understand where does the
> problem come from. I found this post about zoom level management :
> http://osgeo-org.1560.x6.nabble.com/WMTS-Need-TileLevel-option-
> Servers-responding-with-bad-capabilities-td5298089.html
> 
> I tried the xml with gdalinfo and it runs perfectly. I compared with mine and I
> didn't noticed major differences. I also took a comparative look at servers
> capabilities which seems similars. The main difference lays in the TileMatrix
> content.
> 
> Here is "mine":
> <TileMatrixSetLimits>
> <TileMatrixLimits>
> <TileMatrix>10</TileMatrix>
> <MinTileRow>340</MinTileRow>
> <MaxTileRow>400</MaxTileRow>
> <MinTileCol>493</MinTileCol>
> <MaxTileCol>546</MaxTileCol>
> </TileMatrixLimits>
> 
> Here is the one from
> https://basemap.nationalmap.gov/arcgis/rest/services/USGSShadedReliefO
> nly/MapServer/WMTS/1.0.0/WMTSCapabilities.xml
> :
> <TileMatrix>
> <ows:Identifier>10</ows:Identifier>
> <ScaleDenominator>545978.7734656851</ScaleDenominator>
> <TopLeftCorner>-2.0037508342787E7 2.0037508342787E7</TopLeftCorner>
> <TileWidth>256</TileWidth> <TileHeight>256</TileHeight>
> <MatrixWidth>1025</MatrixWidth> <MatrixHeight>1285</MatrixHeight>
> </TileMatrix>

You are comparing apples to oranges. TileMatrixSetLimits/TileMatrixLimits and TileMatrixSet/TileMatrix are not the same thing. The TileMatrix describes a given tile level of the TileMatrixSet. The TileMatrixLimits tell you which part of the TileMatrixSet actually contains data. For instance, the TileMatrixSet might cover the entire world, yet the actually data is only in New Zealand.

> 
> Does that mean "my" WMTS server can't be accessed using the gdal WMTS
> driver or did I miss something ? As far as I understand "my" wmts server is
> only accessible using TILEROW and TILECOL arguments, not a BBox, isn't it ?

WMTS uses zoom level (TileMatrix identifier), x (col), y (row) to access tiles. How that relates to a BBox is calculated from the TileMatrix of the given zoom level.

André

> 
> Below, I have also copied the content of my xml file.
> 
> Regards,
> Hug
> 
> 
> <GDAL_WMTS>
> 
> <GetCapabilitiesUrl>http://wxs.ign.fr/KEY/geoportail/wmts?SERVICE=WMTS
> &REQUEST=GetCapabilities</GetCapabilitiesUrl>
>   <Layer>GEOGRAPHICALGRIDSYSTEMS.MAPS.SCAN-
> EXPRESS.STANDARD</Layer>
> 
>   <TileMatrixSet>PM</TileMatrixSet>
>   <TileMatrix>15</TileMatrix>
>   <ZoomLevel>15</ZoomLevel>
>   <Format>image/jpeg</Format>
>   <DataWindow>
>           <UpperLeftX>666947.416653756</UpperLeftX>
>           <UpperLeftY>5666660.80226639</UpperLeftY>
>           <LowerRightX>674402.416653756</LowerRightX>
>           <LowerRightY>5658330.40226639</LowerRightY>
>   </DataWindow>
>   <BandsCount>4</BandsCount>
>   <Cache />
>   <UnsafeSSL>true</UnsafeSSL>
>   <ZeroBlockHttpCodes>404</ZeroBlockHttpCodes>
>   <ZeroBlockOnServerException>true</ZeroBlockOnServerException>
>   </GDAL_WMTS>
> 
> 
> 
> 
> --
> View this message in context: http://osgeo-org.1560.x6.nabble.com/WMTS-
> No-zoom-level-found-tp5319529.html
> Sent from the GDAL - Dev mailing list archive at Nabble.com.
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