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Hello again, I'm forwarding the message below to the galeon email list; the original message bounced because only members of the list can post to the list. It appears that discussions of topics related to the OGC GALEON Interoperability Experiment have generated interest with several individuals who are not on the galeon email list. My current approach is to forward those messages to the list and subscribe the sender to the list. Of course, I will remove anyone from the list who so desires. I've also created a set of web pages related to WCS GALEON (Web Coverage Service Geo-interface to Atmosphere, Land, Earth, Ocean NetCDF). http://www.unidata.ucar.edu/projects/THREDDS/GALEON/Home.html where we are posting background and status information about GALEON. -- Ben Domenico Unidata Deputy Director GALEON Initiator
---------- Forwarded message ---------- From: Simon.Cox@xxxxxxxx Yes. Perhaps the most important differences between the GML/ISO concept of "coverage" and netCDF and allies are: 1. netCDF etc support rather generalised mappings between arrays. Thus the "domain" of the data (the independent variable, if you like) is not really contrained. In contrast, a geospatial coverage is a specialisation in which the domain must be spatio-temporal, i.e. between 1 and 4 dimensions. As Ron points out, JP2K is even more restricted in this sense - it only supports 2D domains. 2. There is explicit support for registering the domain of a geospatial coverage to real-world locations - the most well-known is where the domain is a rectified grid, but other geometries may be used which are tied to a spatial reference system. 3. As Ron points out, an "Observation" is the act of collecting some values associated with a target. The "result" of an observation is essentially parallel to the "range" in a coverage. The "target" of an observation is parallel to the "domain". The Observation viewpoint focusses on the observation event, and is primarily a means to access metadata associated with property values - how they were obtained, when, by whone, etc. This is of interest when trying to assess data reliability, and for data insertion. Futher down the chain, Observation/result values will often be collated into "coverages" in preparation for some analysis, anomaly or feature-detection, etc. But it is very much the case that the structure of a "coverage" when expressed as a map of the range over the domain is the same as the structure of a an observation which maps a result to a target. See https://www.seegrid.csiro.au/twiki/bin/view/Xmml/ObservationsAndMeasurements for some detail. Simon
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