Re: Sub-properties for locn:geometry? (was: RE: ISA Core Location Vocabulary)

On 2014-01-10 13:00, John Goodwin wrote:
>
> Frans Knibbe wrote:
>
>
> As all the subproperties are geometries themselves, why not define 
> them as subclasses?
>
> The simple feature ontology does subclass geometry to polygons, points 
> etc. Are you suggesting having new classes for things like ‘centroid’ 
> (e.g. subclass of sf:Point) etc?
>
I don't really know... I was thinking that geometries like centroid or 
MBR are specialized geometries. They have additional constraints, like a 
centroid always being a point and a MBR always being a rectangle. So it 
that sense they are much like  simple feature geometry types like point 
or polygon or multiline. But they also have other meanings, like the MBR 
enclosing all geometry and the centroid being a 'center of mass'. So if 
there were RDF definitions for something like the Simple Features 
specification I guess it would make sense to view these new classes as 
subclasses of existing types. But in many current specifications, the 
geometry type is encoded together with the coordinates, NeoGeo being an 
exception. It can be confusing.

Given the idea that a geographical feature like a municipality can have 
many different geometries (for instance with different levels of 
detail), I think the idea is to associate things like centroid or MBR 
with the feature, not with a geometry of a feature. Will that work if 
something like a centroid is a property of a geometry?

Perhaps the LOCN vocabulary should include the notion of a geographical 
feature (something that can be modelled to have geometry), so 
specialised geometries like MBR can be defined as properties of that class?

Regards,
Frans