Re: [wcsplus] [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/UnidataObsConvention.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



On 10/31/07, Gerry Creager <gerry.creager@xxxxxxxx> wrote:
Ben,

Under #4 below, what's being done, to your knowledge, to facilitate
extension of CF-netCDF to support, in some standardized manner or
convention, unstructured/irregular grids?  This continues to be an issue
for the Coastal community and is something I'd love to see addressed.

Thanks, Gerry