Re: SpatialThing and feature (again)

Thanks all. I can amend the BP doc to clarify as per Simon's proposal.
Jeremy
On Tue, 25 Apr 2017 at 12:54, Matthew Perry <matthew.perry@oracle.com>
wrote:

> That looks correct to me as well.
>
> Thanks,
> Matt
>
> On 4/25/2017 12:29 AM, Joshua Lieberman wrote:
>
> Yes, I think.
>
> On Apr 25, 2017, at 12:19 AM, <Simon.Cox@csiro.au> <Simon.Cox@csiro.au>
> wrote:
>
> Ø  ... and reaffirm that _we_ see Feature (SpatialThing) as disjoint from
> geometry, but that this might be at odds with some people's
> interpretations. As Josh says: "we can’t really say there is a mapping from
> W3C Basic Geo to/from anything based on 19109."
>
> We need to be very clear here:
>
> geosparql:SpatialObject         includes both features and geometries –
> they are disjoint subclasses
> w3cgeo:SpatialThing               is superclass of w3cgeo:Point, but (OWA)
> potentially also has a class of features as another subclass (disjoint from
> Point) – so this could all be OK and consistent (but we mustn’t credit
> w3cgeo as having been the result of much deep thought).
>
> So where does bp:SpatialThing fit in? Looks to me like the key thing is to
> point out that it is **not** the same as w3cgeo:SpatialThing, because the
> latter includes geometries. But it **is** the same as geosparql:Feature,
> which is disjoint from Geometry.
>
> Simon
>
> *From:* Clemens Portele [mailto:portele@interactive-instruments.de
> <portele@interactive-instruments.de>]
> *Sent:* Tuesday, 25 April, 2017 01:27
> *To:* Jeremy Tandy <jeremy.tandy@gmail.com>
> *Cc:* Josh Lieberman <jlieberman@tumblingwalls.com>; Cox, Simon (L&W,
> Clayton) <Simon.Cox@csiro.au>; Rob Atkinson <rob@metalinkage.com.au>;
> Andreas Harth <harth@kit.edu>; public-sdw-wg@w3.org
> *Subject:* Re: SpatialThing and feature (again)
>
> Hi Jeremy,
>
> I think we should add a green note in chapter 5 to explain how the
> "anything with spatial extent" definition is consistent with features like
> a "home loan" in a spatial dataset as it is not obvious.
>
> Clemens
>
>
>
> On 21. Apr 2017, at 17:33, Jeremy Tandy <jeremy.tandy@gmail.com> wrote:
>
> Hi all-
>
> I've spent more than a few minutes parsing through the email chain.
>
> 1/ Clemens' summary (from mid way though) suggests that (a) ISO 19109
> Feature is [also] a geosparql:Feature, (b) these may or may not have
> attached geometry properties
> 2/ Andrea suggests that "only [those] ISO 19109 Features [with spatial
> extent] are Spatial Things according to the BP definition" - but Josh
> suggests we're using "spatial extent" as a shorthand for "real-world
> phenomena", and that "making the connection [between abstraction and
> real-world thing] formal and explicit is not necessary for Web purposes"
>
> So I'm seeing that there's no inconsistency to explain away.
>
> Please confirm that I've read this OK. Apologies if I've missed the point!
>
> And, talking of Points ... I see that there is potential for confusion
> regarding the "Feature/Geometry amalgam".
>
> We could insert a "green note" into the BP document identifying the
> potential for inconsistency - as defined in Andreas' example:
>
> > 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.
>
> ... and reaffirm that _we_ see Feature (SpatialThing) as disjoint from
> geometry, but that this might be at odds with some people's
> interpretations. As Josh says: "we can’t really say there is a mapping from
> W3C Basic Geo to/from anything based on 19109."
>
> Am I summarising correctly?
>
> Thanks, Jeremy
>
>
> On Fri, 21 Apr 2017 at 15:33 Joshua Lieberman <
> jlieberman@tumblingwalls.com> wrote:
>
> Ah, I had thought that the domains of geo:lat and geo:lon were geo:Point,
> since that is what is generally referred to in narrative. If a resource
> carrying the lat/lon properties implies that it is a SpatialThing, not only
> the Point subclass, adding the properties doesn’t resolve any feature /
> geometry ambiguity. Your equivalences are certainly possible, but geosparql
> doesn’t / shouldn’t support adding direct positions to features, so
> entailing something with geo:lat and geo:lon as geosparql:SpatialObject
> rather than geosparql:Geometry doesn’t really work. And if we can’t derive
> that use of geo:lat and geo:lon imply both a feature and a geometry, than
> Andrea is correct that we can’t really say there is a mapping from W3C
> Basic Geo to/from anything based on 19109. That may be unfortunate.
>
> —Josh
>
>
> On Apr 20, 2017, at 8:38 PM, simon.cox@csiro.au wrote:
>
>
> Hold on a moment folk – does this problem really exist?
>
> I’m looking at http://www.w3.org/2003/01/geo/wgs84_pos#
> <http://www.w3.org/2003/01/geo/wgs84_pos> which is the RDF/XML
> serialization of W3C Basic Geo.
> Here’s the key axioms.
>
> geo:lat   rdfs:domain geo:SpatialThing .
> geo:long rdfs:domain geo:SpatialThing .
> geo:Point rdfs:subClassOf geo:SpatialThing .
>
>
>
> And from http://schemas.opengis.net/geosparql/1.0/geosparql_vocab_all.rdf
> since
>
> geosparql:Geometry rdfs:subClassOf geosparql:SpatialObject .
>
> then it looks to me like
>
> geo:SpatialThing owl:equivalentClass geosparql:SpatialObject .
> geo:Point rdfs:subClassOf geosparql:Geometry .
>
> and there is no inconsistency. Appearance of geo:lat and geo:long
> properties only entails that it is a geosparql:SpatialObject, so can be
> either a Feature or a Geometry.
>
> Am I missing something?
>
> Simon
>
> *From:* Rob Atkinson [mailto:rob@metalinkage.com.au
> <rob@metalinkage.com.au>]
> *Sent:* Thursday, 20 April, 2017 06:24
> *To:* Joshua Lieberman <jlieberman@tumblingwalls.com>; Andreas Harth <
> harth@kit.edu>
> *Cc:* public-sdw-wg@w3.org
> *Subject:* Re: SpatialThing and feature (again)
>
>
> This could also be resolved by thinking of geo:long as a property that can
> entail a geometry property of the feature - maybe its even a geometry
> property in the same way that a 2D point is a partial representation of a
> 3D location?
>
> Rob
>
> On Thu, 20 Apr 2017 at 02:38 Joshua Lieberman <
> jlieberman@tumblingwalls.com> wrote:
>
> 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#
> <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#
> <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.
> >
> >
>
>
>
>