Re: SpatialThing and feature (again)

Andreas,

It may not be worth delving too deeply into this... 

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 is a similar property in GeoRSS, the point(pos) property, but this doesn’t try to create one feature-geometry amalgam. It’s simply a shortcut for a longer expression that identifies some resource as a _Feature with a “where" object property connecting to a Point geometry resource.

It might be most accurate to say that your example of using W3C Basic Geo to represent feature and geometry in the “style” of geosparql is actually the longhand of what people are trying to do when they do use geo:lat and geo:long, identifying a resource as a real world feature and giving it a closely allied point geometry.

—Josh

> On Apr 19, 2017, at 11:54 AM, Andreas Harth <harth@kit.edu> wrote:
> 
> Hi,
> 
> On 04/19/17 13:29, Joshua Lieberman wrote:
>> My understanding based on the limited documentation is that w3cgeo:SpatialThing covers both features and models such as geometries, so
> 
> that's my understanding too.  With the W3C WGS84 vocabulary you can write:
> 
> @prefix geo: <http://www.w3.org/2003/01/geo/wgs84_pos#> .
> @prefix : <#> .
> 
> :bob a geo:SpatialThing ; geo:lat "52.5196143" ; geo:long "13.4065603" .
> 
> So the resource with the URI :bob is both the "feature" and the "geometry".
> 
> In other representations (NeoGeo, GeoSPARQL), you would identify two separate
> resources:
> 
> @prefix geo: <http://www.w3.org/2003/01/geo/wgs84_pos#> .
> @prefix : <#> .
> 
> :bob a :Feature ; :geometry _:bnode .
> _:bnode a :Geometry , geo:Point ; geo:lat "52.5196143" ; geo:long "13.4065603" .
> 
> The URI :bob now represents the "feature" resource, and the blank node _:bnode
> represents the "geometry" resource.
> 
> I wouldn't know how to write OWL axioms to map the two modeling choices though.
> 
> Best regards,
> Andreas.
> 
>

Received on Wednesday, 19 April 2017 16:39:47 UTC