|
Quatation from Web Coverage Service Interface Standard - CRS Extension
> Requirement 21 crs-gridded-coverage/getCoverage-rangeSet:
> The range values of the response to a successful GetCoverage request containing an
> outputCrs parameter shall be determined according to the following conceptual
> evaluation model: Take the bounding box of the request’s subsetting parameter (or the full
> coverage bounding box if no subsetting was specified in the request); re-project this
> bounding box to the output CRS provided; generate the result image extent as the smallest
> bounding box around the reprojected subsetting box; fill this new image extent with pixel
> values re-projected from the coverage’s Native CRS to the output CRS in a way that, for each
> axis, the smallest distance between any two reprojected grid points is used as offset
> (including all interpolation and resampling necessary) unless specified otherwise by further
> request parameters.
I understand that “fill this new image extent with pixel values” means that if the coverage source has data available then the output image should be full without no-data pixels. This does not seem to be the case with Geoserver 2.14-Snapshot. It seems that the subsetting envelope is converted into native CRS, the subset of coverage is clipped while in the native CRS, and finally the clipped image is warped into OutputCRS. This leads to nodata areas in the output.
Test request:
http://localhost:8080/geoserver/wcs?service=WCS&version=2.0.1&request=GetCoverage&CoverageID=nurc__Img_Sample&format=image/geotiff&SUBSET=E(-859802,1648495)&SUBSET=N(2361997,4509563)&subsettingcrs=http://www.opengis.net/def/crs/EPSG/0/32612&OutputCRS=http://www.opengis.net/def/crs/EPSG/0/32612
|
