Forum: WebMapViewer Forum

WCS download: Resolution parameter

Dear WebMapViewer Team,

may I issue a feature request or maybe a correction of inconsistency.

Using the coverage download feature in the SOSI project we see that the resolution parameter doesn't take the respective CRS unit into account. In our case we have a national projection with unit meters and a resolution of 20. In the coverage download tab the 20m resolution is displayed together with EPSG:4326 selected which makes no sense since EPSG:4326 expects the resolution to be in degree. I propose to either select the correct CRS by default or to recalculate the resolution parameter.

Our WCS service is available at following URL:
http://www.eox.at/sosi-ows?service=WCS&request=DescribeCoverage&coverage=SOSI-SS2006-A&version=1.0.0

Because the access is restricted on IP addresses I attach the DescribeCoverage response.

Many thanks,
Stephan


Re: WCS download: Resolution parameter

Stephan,

This is a difficult one.
When the coverage download window is prepared, the WebMapViewer uses the following logic:
- Coordinate Reference System is the one that is currently active on the map- and that the BBOX that comes from the map extent or Area Of interest is expressed in.
- resolution and image size are taken from the gml:RectifiedGrid within the describeCoverage information (offsetvector and gridEnvelope respectively).

We could perhaps propose as default download CRS the nativeCRS (If it is declared in the DescribeCoverage response).
Issues with this approach are that this nativeCRS element is apparently not mandated and that we then need to reproject the Bounding Box from the map CRS to the Native CRS.

Would this proposed approach solve your issue?


Re: Re: WCS download: Resolution parameter

Thanks for your response.

Using the nativeCRS as the default download CRS would be OK for us.

You could use the "crs" and "response_crs" parameters to leave the bouding box reprojection to the service and looking at our logfiles you already do this:

/sosi-ows-tmp?bbox=12.94226,47.72287,13.11235,47.87091&coverage=SOSI-SS2006-A&crs=EPSG:4326&format=GTIFF&interpolation=nearest+neighbor&request=GetCoverage&response_crs=EPSG:31287&resX=20.0&resY=20.0&service=WCS&version=1.0.0 /sosi-ows-tmp?bbox=12.94226,47.72287,13.11235,47.87091&coverage=SOSI-SS2006-A&crs=EPSG:4326&format=GTIFF&interpolation=nearest+neighbor&request=GetCoverage&response_crs=EPSG:4326&resX=3.0E-4&resY=3.0E-4&service=WCS&version=1.0.0


Best regards,
Stephan




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