Re: SpatialThing and feature (again)

Hi Joshua,

On 04/19/17 18:38, Joshua Lieberman wrote:
> It may not be worth delving too deeply into this...

I think you are right as long as one doesn't try to map vocabularies
and data that assume the Feature/Geometry distinction to those that
assume a Feature/Geometry amalgam.

> W3C Basic Geo defines SpatialThing and then subclasses it to Point
> carrying the lat and long properties. No one defines their own
> SpatialThings, they simply add geo:lat and geo:long properties to
> some resource X to turn it into “also a Point”, in other words “also
> a geometry”. This implies for most users but does not actually assert
> that resource X is both a feature and a geometry. One could form a
> subclass of geo:SpatialThing that was actually disjoint with
> geo:Point or other geometry,  which would then align more-or-less
> with iso geosparql:Feature, hence the assertion that some
> geo:SpatialThings are geosparql:Features. This is largely
> hypothetical.

There are a lot of instances of geo:SpatialThing out there on the web.
If you assume that people integrate data and add reasoning there's
a good chance one ends up with inconsistencies very quickly.  Here's
how.

Because a w3cgeo:SpatialThing has lat/lon, some people might equate
a w3cgeo:SpatialThing with a geosparql:Geometry.

Because the w3cgeo:SpatialThing is an instance of foaf:Person, some
other people find it natural to equate the w3cgeo:SpatialThing
with a geosparql:Feature.

Based on data from different source we now have an inconsistency,
because the w3cgeo:SpatialThing is an instance of both geosparql:Feature
and geosparql:Geometry, which are defined as disjoint.

We just might need to acknowledge that there is no good solution for
mapping RDF data that assumes the Feature/Geometry distinction to
RDF data that assumes a Feature/Geometry amalgam.

Cheers,
Andreas.

Received on Thursday, 20 April 2017 09:52:14 UTC