Re: SpatialThing and feature (again)

Hi Andreas,

"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.”

I think you mean here foaf:Person is a subclass of w3cgeo:SpatialThing (as well as of foaf:Agent). That and a couple of other terms are derived (by Danbri) specifically as features, not geometries from w3cgeo:SpatialThing. If, however, one adds geo:lon and geo:lat to an instance of foaf:Person, one gets an entity that is both a Person feature and a w3cgeo:Point. I suspect that is actually necessary to do this implicit mapping into a feature and a geometry in order to make sense of the ways in which w3cgeo:SpatialThing is used. I agree that it wouldn’t make sense to map the other way, back to some feature-geometry amalgam.

—Josh

> 
> On Apr 20, 2017, at 5:51 AM, Andreas Harth <harth@kit.edu> wrote:
> 
> 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.
>