[gdal-dev] WCS GetCoverage with AxisOrder swap

Ari Jolma ari.jolma at gmail.com
Wed Nov 8 13:01:34 PST 2017


Even Rouault kirjoitti 08.11.2017 klo 17:31:

> On mercredi 8 novembre 2017 15:50:48 CET Piero Campalani wrote:
>
>
> > This order is what can be referred to in the GridFunction: +1 --> first
>
> > GRID axis, +2 --> second GRID axis, etc.
>

Ok, this tells me that the axisOrder attribute in sequenceRule 
determines how to consider the GridEnvelope and the order of the 
offsetVectors in the Grid element.

>
>  And thus MapServer output at
>
> http://194.66.252.155/cgi-bin/BGS_EMODnet_bathymetry/ows?SERVICE=WCS&REQUEST=DescribeCoverage&version=2.0.1&coverageid=BGS_EMODNET_CentralMed-MCol
>
> could probably be correct, but it would be better for 
> RectifiedGrid.axisLabels to be changed to "long lat" to better
>
> reflect what is done.
>

At least it fixes the driver for MapServer in this case (no hack options 
needed) since it does not define the axisOrder.

> And GeoServer output at 
> https://msp.smartsea.fmi.fi/geoserver/wcs?SERVICE=WCS&REQUEST=DescribeCoverage&VERSION=2.0.1&COVERAGEID=smartsea__eusm2016-EPSG2393
>
> would either need to remove the GridFunction (ala MapServer) or keep 
> it and invert the order in which its offsetVector appear (ala Rasdaman)
>

Invert the offsetVector order *and* invert the axis in GridEnvelope 
(otherwise the size is wrong).

> And for WCS subsetting, when you write something like 
> SUBSET=AXIS_NAME(min,max),
>
> where AXIS_NAME should come from ? From the RectifiedGrid.axisLabels I 
> guess ?
>
> (to be opposed to CoverageDescription.boundedBy.Envelope at axisLabels)
>
> Then in Ari's test with GeoServer
>
> https://msp.smartsea.fmi.fi/geoserver/wcs?SERVICE=WCS&REQUEST=DescribeCoverage&VERSION=2.0.1&COVERAGEID=smartsea__eusm2016-EPSG2393, 
> in theory "i" and "j" should be the axis requested ?
>

That does not work -- it's good that they are different since that shows 
it is not ok (invalid axis label error). Maybe the logic is related to 
the axis names? It's hard to tell since I don't find the logic in the 
GeoServer source code.

Ari

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