Thanks you very much Frank for the clarification. You confirm what I understood.
Best regards, Bruno On 11 February 2010 16:54, Frank Warmerdam <[email protected]> wrote: > Bruno Binet wrote: >> >> Hi list, >> >> I'm currently trying to use the wcs gdal driver to extract data from a >> wcs service (mapserver), using a specfic projection, extent and >> resolution. >> I managed to extract the all dataset in the original projection, and >> format (geotiff). >> But I would like to be able to specify a value for the format, the >> extent, the projection, and the resolution for the data to be >> extracted. >> >> Given the docs: http://www.gdal.org/frmt_wcs.html we can specify a >> preferred format for extraction with the PreferredFormat element, but >> what about projection, extent, and resolution? >> Do we have to download the entire dataset and use gdal capabilities to >> extract and reproject a subset of the downloaded data? >> It would be great if it could be handled directly by mapserver. > > Bruno, > > I have skimmed the WCS driver implementation and it does not appear > to be convenient to request data in a projection other than the default. > Basically the driver really wants to establish an image size and it does > this from the GridCRS/BoundingBox (1.1) or GridEnvelope (1.0) and this > information is generally (always?) only available for the default coordinate > system. > > It might be possible for you to manually massage all these values in > the CoverageOffering/CoverageDescription in the GDAL WCS control file > to "fake it out" as if another coordinate system was the default. However, > I've never tried that and it might be fairly hard to get right. > > As things are currently setup, it is really intended that GDAL "knows" the > true native coordinate system, grid size and georeferencing and accesses > on that basis. > > Best regards, > -- > ---------------------------------------+-------------------------------------- > I set the clouds in motion - turn up | Frank Warmerdam, > [email protected] > light and sound - activate the windows | http://pobox.com/~warmerdam > and watch the world go round - Rush | Geospatial Programmer for Rent > > -- Bruno Binet Camptocamp France SAS Savoie Technolac, BP 352 73377 Le Bourget du Lac, Cedex Mail : [email protected] http://www.camptocamp.com _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
