Re: Area of spatial objects

Thanks for the responses everyone. I will proceed as follows:



*         I will invent an Area class

o    sameAs to http://qudt.org/vocab/quantity#Area

o    published properly (conneg, PID URI etc.)

o    will deprecate in favour of QUDT if/when its v2 is better published

*         I will invent a hasArea property

o    range restricted to Area class from above

o    I want to associate area with a Feature, not a Geometry (in reply to Frans' suggestion to chain Feature -> Geometry -> Area) as I believe area is/should be stand-alone, and not dependent on a Geometry but may usage note suggest this, rather than domain restrict it

*         I will represent differences in area types ("normal" v. Albers) using provenance

o    Thanks Jo Abhayaratna for the prompt

o    So perhaps something like this:



<feature_x>

    ex:hasArea [

        # inferred to be of type new Area class

        qudt:numericValue "12345678"^^xsd:decimal ;

        qudt:unit qudt:SquareMeter ;

        prov:wasGeneratedBy [

               # inferred to be a prov:Activity ;

               prov:used <http://example.com/area-method/normal> ; # a prov:Plan

        ] ;



   ] ;

    ex:hasArea [

        # inferred to be of type new Area class

        qudt:numericValue "12345678"^^xsd:decimal ;

        qudt:unit qudt:SquareMeter ;

        prov:wasGeneratedBy [

               # inferred to be a prov:Activity ;

               prov:used <http://example.com/area-method/albers> ; # a prov:Plan

        ] ;

   ] ;

] ;



I may implement a shortcut for the new Area class prov:wasGeneratedBy prov:Activity prov:used prov:Plan chain, perhaps:



ex:hasArea [

        ...

        ex:wasCalculatedUsingMethod <http://example.com/area-method/albers> ;

] ;



Before doing this I will look for pre-existing shortcuts properties in PROV, SSN etc. that link a prov:Entity to a prov:Plan via an prov:Activity



*         I will submit the implemented classes, properties & axioms to GeoSPARQL for their next version

o    Thanks Joshua Lieberman for the prompt

*         I will reply back to this list when results are published



Any further suggestions welcome!



Thanks,



Nick





> On 10/26/18 12:19 AM, Simon.Cox@csiro.au<mailto:Simon.Cox@csiro.au?Subject=Re%3A%20Area%20of%20spatial%20objects&In-Reply-To=%3Ccdbb0740-56d0-d7dc-a356-661dff132738%40ucsb.edu%3E&References=%3Ccdbb0740-56d0-d7dc-a356-661dff132738%40ucsb.edu%3E> wrote:

>>

>> Yes, it is the SI unit, but units are not inherent in the definition

>> of the quantity-kind `area`.

>>

>> Binding units of measure into the quantity-type definition is a

>> convenient shortcut in some application contexts, but this conflates

>> two concepts so the result is no longer a quantity-kind, but is a

>> "scaled-quantity-kind".

>>

>> There are other units of measure used for area.

>>

>

> Very well said and an important distinction. The square meter is the

> basis for the scalar, not the property itself.