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Gerry, We also have the same problem with lack of support (in data models) for unstructured/irregular grids for our coastal models. ISO 19123 is big enough to handle them, but both the NetCDF and the GML communities don't have this in their implementations. Although GML is now in revision to handle irregular spacing in grids, it still doesn't handle unstructured grids. If anyone is putting a project together to address this, we'd be happy to support it. Keiran
-----Original Message----- From: galeon-bounces@xxxxxxxxxxxxxxxx [mailto:galeon-bounces@xxxxxxxxxxxxxxxx] On Behalf Of Ben Domenico Sent: 31 October 2007 20:54 To: Gerry Creager Cc: Unidata GALEON; WCS 1.0 Plus Subject: Re: [galeon] WCS 1.0 Plus philosophy and objectives Hi Gerry, As you are no doubt aware, that issue has to be addressed on multiple fronts. -- The ISO 19123 definitions are general enough to support such datasets as coverages. -- The WCS specifications have been more restrictive to the point where the grids must be regular in some (perhaps) projected coordinate system. -- The CF conventions community has, to this point, focused on the regular (or at least quasi regular) grids that are the output of numerical forecast models. So a multi-pronged approach must be taken if we are going to develop standard interfaces to the sort of unstructured/irregular grids the coastal community deals with. A somewhat different, but closely related data type, results from the collections of time series of observations at atmospheric, oceanographic, hydrological, and other observing stations. There is an initiative underway to either extend the CF conventions to include this type of datasets or to define a parallel set of conventions. http://www.unidata.ucar.edu/software/netcdf-java/formats/Unida taObsConvention.html These conventions can then be mapped to the ISO 19123 general data model and hopefully, in the end, included as a means of encoding the semantics of those datasets. A similar process can be used for the other major "scientfic data types" of the Common Data Model (CDM), e.g., trajectory, swath, radar radial. While we need a process that is general enough to work for all those data types, I don't see any way to make them all happen at once. For each type, we need to specify a mapping to ISO, conventions equivalent to CF, and then an encoding specification that will work in the WCS context. We're in pretty good shape for regular grids while the case of irregular grids still needs some work. If we can complete the process for the case of "station observations," I believe the others will follow more quickly by benefit of the hard lessons we are learning from the first two. One question I have for you and the other members of the coastal community is whether those unstructured/irregular grids are an example of one of the current CDM scientific data types http://www.unidata.ucar.edu/projects/THREDDS/CDM/CDM-TDS.htm or whether a new CDM data type is needed. -- Ben
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