Re: [galeon] WCS CF-netCDF profile document

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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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