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#107: CF Data Model 1.7 -----------------------------+---------------------------------------------- Reporter: markh | Owner: [email protected] Type: task | Status: new Priority: medium | Milestone: Component: cf-conventions | Version: Resolution: | Keywords: -----------------------------+---------------------------------------------- Comment (by jonblower): I haven't followed this conversation in detail so hopefully I'm not repeating something. In general, I think it's a good idea to separate the concept of a transform from the concept of a coordinate reference system. I think CF should allow the serialization of CRSs, but not necessarily transforms. My view is coloured by how the Java library Geotoolkit addresses this, which I think works well. A transform is just a function that does not need to know anything about georeferencing - it just takes input values and produces output values. It can be derived from two CRSs (e.g. [http://www.geotoolkit.org/apidocs/org/geotoolkit/referencing/CRS.html#findMathTransform%28org.opengis.referencing.crs.CoordinateReferenceSystem,%20org.opengis.referencing.crs.CoordinateReferenceSystem%29 like this]) or by other means. The point is that a transform between two CRSs may not always exist in a readily-serializable mathematical form. Different applications may be happy with different levels of precision in transforms (e.g. sometimes the datum shift is ignored). In short: I would suggest recording the CRS in CF-NetCDF files, but letting applications find the transformation between CRSs. In fact, I think the examples above do describe a CRS, not a transform. (The [http://www.geoapi.org/snapshot/pending/org/opengis/referencing/operation/MathTransformFactory.html Javadoc for MathTransformFactory] has some more info.) -- Ticket URL: <https://cf-pcmdi.llnl.gov/trac/ticket/107#comment:22> CF Metadata <http://cf-pcmdi.llnl.gov/> CF Metadata This message came from the CF Trac system. To unsubscribe, without unsubscribing to the regular cf-metadata list, send a message to "[email protected]" with "unsubscribe cf-metadata" in the body of your message.
