RE: Best Practice for encoding spatial coverage

Frans -
You really don't have to make this up afresh.
ISO 19107 defines a property 'envelope' for any geometry, with a value of type GM_Envelope, which has a lower and upper corner, whose values are points.
ISO 19123 defines a property 'domain extent' for any coverage, with a value of type EX_Extent, which is a bit more complex (defined in ISO 19115).
There is no standard property for the corresponding thing for a generic feature, but 'bounding box' is a common name.

Simon

Caveat lector - Sent from a tablet using TouchDown

________________________________
From: Frans Knibbe
Sent: Wednesday, 17 June 2015 9:53:42 AM
To: SDW WG Public List
Subject: Best Practice for encoding spatial coverage

Hello all,

Is it OK to try to venture in to the domain of best practices already? I wonder if we can try our hands at the following issue:

I have just had a talk with a web developer on the best way of making the extent of a spatial data set known, in a Linked Data context. It is useful to know the spatial extent of a data set because that way a map can be zoomed in on the right patch of Earth.

I think an obvious predicate for making the extent known is dcterms:spatial<http://dublincore.org/documents/dcmi-terms/#terms-spatial> (Spatial Coverage). That should point to a dcterms:Location<http://dublincore.org/documents/2012/06/14/dcmi-terms/?v=terms#terms-Location>, which can have a geometry. So an option would be to encode the extent as a WKT polygon, according to GeoSPARQL semantics. But that would not be the most webdeveloper-friendly way of making the extent known.  The usual way of setting a map extent involves knowing the minimum and maximum values for X and Y. So a question is: what would be the best way to publish the minimum and maximum X and Y? There are usable vocabularies for publishing point coordinates, so one could think of recommending to publish two points (lower left corner and upper right corner). Perhaps there are standard vocabularies available that define the concepts of 'minimum' and 'maximum' and 'x' and 'y'?

I should note that this issue relates to the Spatial metadata requirement<http://w3c.github.io/sdw/UseCases/SDWUseCasesAndRequirements.html#SpatialMetadata>.


Greetings,
Frans



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