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See comments inline. Ron
Just one note, quickly added: Wright, Bruce wrote:1. Coverages and features are different...WFS and WCS evolved as two distinct services to meet different requirements for accessing data and metadata.this is past and presence, IMHO.2. A coverage is a feature...features and coverages are different 'cross-sections' through the information - Simon Cox presents this nicely by considering the information as tabular, with a row represents a feature (a series of individual property values) and a column representing a coverage (different values of the same property) - and the WFS and WCS should be harmonised.hm, that seems like adding a third, radically new concept to unify the two others. Why not simply say "a coverage is a feature which enjoys special treatment, as laid down in the WCS".3. A feature is a coverage...coverages are already effectively being encoded in GML for some WFS requests that need to return the variation of a set of parameters over space/time (normally small data volumes); again, this suggests that the WFS and WCS should be harmonised.
[RTL] In the ISO model, Coverages are Features and this approach was followed in GML since Version 3.0. A number of early WFS implementations provided raster coverages - usually as results of Observations - this discussion seems to have been going on for quite a number of years (~ 10).
well, I have nothing against GML as one _additional_ data format (and a proof that something is possible). All the mapping people I have talked to, however, want to first webify their vector material and then their rasters - current practice, alas, has made WFS the first-born son ;-)4. Coverage is a property of a feature... WCS is a convenience interface, which should eventually replaced by an enhanced WFS, which adds a GetCoverage request (or an OPeNDAP request!)
[RTL] It makes perfect sense to have coverage valued properties of a feature. For example, a photo-log of a road or simply the surface texture of the road could be represented as a coverage.
oops, that sounds complex - just a property (aka attribute) of a feature? We might adopt #2 and come to the same conclusion.Personally, I think these are all true to some extent (not sure 3. above is a good thing though!). However, which viewpoint you take determines how you develop and implement these web services going forward (e.g. my explicit 'conclusion' on 4. above!).
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