Re: A proposal for two additional properties for LOCN

Le 16 sept. 2014 à 16:42, Frans Knibbe | Geodan <frans.knibbe@geodan.nl> a écrit :

> Suppose we want to have something called spatial resolution. We want it to have a numerical value (e.g. "1.405"^^xsd:decimal) and a unit (e.g. http://qudt.org/vocab/unit#Meter). The unit can not be fixed, because we want to allow other appropriate units, like feet or radians. However, inappropriate units (like kilogram or volt) should not be allowed. 
> 
> I think the fact that we want to have a compound expression for spatial resolution (value + unit) means that a class needs to be introduced, locn:SpatialResolution for instance. Now I wonder if there is a nice class in QUDT of which this class could be a subclass, something from which follows that the spatial resolution has a number and a specififcation of a unit.
Maybe this class can help?! qudt:QuantityValue ? Better to look at this namespace http://qudt.org/1.1/schema/OSG_quantity-(v1.1).ttl  
> If we only consider cartesian spatial reference systems, it could be http://qudt.org/vocab/quantity#Length. But then it would not be possible to express the spatial resolution as a number of degrees or radians. 
> 
> Could or should we make use of a combination of  http://qudt.org/schema/qudt#LengthUnit and http://qudt.org/schema/qudt#AngleUnit?

Hi Frans,
Let see I’ve understood your thoughts ;)
We can use a restriction on the property that links ex:resource to a locn:SpatialResolution. 
I call it locn:hasResolution below, and I put restrictions in the range to only take into account quantity values that are length and angle units. We can maybe also use owl:unionOf in the restriction ? 

############### start here in Turtle##########
PREFIX qudt: <http://qudt.org/1.1/schema/OSG_quantity-(v1.1).ttl> .

locn:hasResolution a owl:ObjectProperty;
	rdfs:label "link to a spatial Resolution"@en;
	rdfs:domain locn:SpatialResolution;
	rdfs:range [a  owl:Class ;
		owl:intersectionOf
			(qudt:QuantityValue
             [ a owl:Restriction;
			  owl:allValuesFrom qudt:AngleUnit, qudt:LengthUnit;  ## (*)
			  owl:onProperty qudt:unit
				]
			 )
				 ];
           . 
 ######### end here the sample #################
(*) Maybe it is not allowed to use different classes with owl:allValuesFrom. I need to check it out.

WDYT ?

Cheers,
Ghislain