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Hi Wenli: Thanks very much for your summary. Two questions: 1) does the core define any GetCoverage response? GML? GeoTIFF? 2) What limits are placed on what a community like Galeon can do when we define "our" extension? Regards, John Wenli Yang wrote:
Hi John et al, You Asked: Can anyone who knows WCS 1.2 summarize 1) whats in the core, and 2) what is allowed in the extensions? The core/extension discussions are documented in the following page/document: http://portal.opengeospatial.org/twiki/bin/view/WCSrwg/DivideSpecificationIntoBasePlusExtensions http://portal.opengeospatial.org/files/?artifact_id=22874&version=1 Unfortunately one needs to be an OGC member to read them. I try to summerized the key capabilities of core and extension bellow. Core capabilities: a) support 2D spatial/temporal domain, essentially the two (near) horizontal spatial dimensions, which are most commonly lat/lon coordinates but can be any other projected coordinates; b) support one 2D range field (i.e., one variable with 2 dimensions); c) do not have to support subset of range field, i.e., do not have to support subset of non-spatial/temporal axes of a variable, which may be >2D array; and d) Support nearest neighbor interpolation. Extensions: a) Support additional spatial/temporal dimensions other than two (near) horizontal ones, such as a variable having three dimensions X, Y, and Z; b) Support more than one range field (variable); c) Support vector range fields, i.e., variables having one or more non-spatial/temporal axes, such as a variable having a "wavelength" axis. NOTE: in OGC terminology, "dimension" is use for spatial/temporal axes or domain while non-spatial/temporal axes are called "axes" in the range side.d) Support subset along range axes.BTW, for format profile, I think that any "WCS extension" profile should not try to disallow anything allowed in any widely used self-described format, such as CF-netCDF. The extension can include additional information considered necessary for OGC/WCS community to better understand the base-format already widely used but might be lacking certain information for the WCS community. A "WCS extension" of CF-NetCDF3 must be a valid CF-NetCDF3, just as a CF-NetCDF3 file itself is a valid netCDF file. I have not carefully reviewed the draft extension Ben and Stefano edited but I think that the extension does not try to change anything required in the "standard" CF-NetCDF3 and thus any file encoded by such extension is fully understandable by any tool that understand "standard" CF-netCDF3. By making WCS-extension, we are make available of the metaocean data available by the WCS community. Similarly, with such extension, users in the metaocean community may request data origina lly encoded in other formats, such as GeoTiff, in other communities. Of course, this is based on the assumption that WCS servers are available. Regards, Wenli
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