Hi Ron & all,
conceptually I find myself comfortable with the idea of a coverage being
just a special case of a feature, while I also see the arguments for the
opposite view. Anyway, mathematicians like Ron can teach us how unified
concepts can be defined.
Practically I see that feature and coverage operations are substantially
different, and it makes sense to have different services on features and
coverages. WFS and WCS form two underpinning services, catalog services
a third one, somehow reflecting the long-standing triad
vector/raster/meta data.
Recently SWE has joined the arena, and I find it important and
interesting to make sure that SWE concepts are in sync with both feature
and coverage definitions (my superficial knowledge of the SWE world
makes me believe that sensor data see themselves sometimes to features
and sometimes to coverages, depending on data, purpose, and daylight
savings time).
_Ideally_ operations on similar data structures are compatible, at least
coherent (eg, sensor and coverage data subsetting). On the other hand I
consider it _essential_ that the structures are in sync across specs
(ie, coherent with whatever we put in OWS Common), otherwise I don't see
how we can achieve cross-standard interoperability: what if two
standards define and use "feature" differently, use "coverage"
differently...
cheers,
Peter
Ron Lake wrote:
Hi Ben:
I think this is also an argument that SOS, WFS and WCS be thought of
as variations of one another - I think of a coverage server as a kind
of WFS (even more so for SOS).
