Re: DAML-Spatial Primitives

From: Adam Pease (
Date: 03/10/03

  • Next message: Pete Haglich: "Re: DAML-Spatial Primitives"
    At 12:56 PM 3/10/2003 -0500, Pete Haglich wrote:
    >The "locus" vs "location" was a throwaway ancedote about a particular 
    >customer, I didn't mean for people to read too much into it.
    Ok, sorry if I read too much into this.
    >As far as the nature of a city being a point vs being a region, I think it 
    >goes a bit deeper than what you suggest and it depends on the granularity 
    >of the discourse.  For example, for travel itineraries, cities are often 
    >treated as points.
    Interesting.  If I type a city into Yahoo and ask for directions, it 
    chooses a default address within the city.  When I get a travel itinerary, 
    it's to a specific airport associated with a city.  This still seems like 
    an interface issue.  The objective reality is that a city is a region.  One 
    may abstract it to a vague point in discourse or GUI, but that doesn't 
    change the facts of what a city is.  If one builds that abstraction into 
    the ontology itself, that dramatically limits one's ability to reuse the 
    ontology in a different content, or integrate with a GIS or other 
    repositories of date, which are the purported benefits of using ontologies 
    to begin with.
    >However, there are other cases where the "two dimensional properties" of a 
    >city are important.  In our use of spatial ontology we have found it 
    >useful to accomodate both viewpoints.  I should note, though, that in our 
    >use of DAML we don't have something like a "TerritoryFn" which might map 
    >an idealized city point to the territory within the city limits.
    >On Monday, Mar 10, 2003, at 12:42 US/Eastern, Adam Pease wrote:
    >>   That sounds like a lexicon issue, rather than an ontology issue.  If a 
    >> human user wants to use a particular term, that's an issue for the 
    >> interface.  A lot of problems occur when one tries to adjust an 
    >> ontology, which must support inference, to conform to a human's 
    >> linguistic conventions.  We've found that it's straightforward to keep 
    >> the two distinct, and have a lexicon file that maps to terms in an 
    >> ontology.  That also makes it easier to use the same ontology for users 
    >> who speak different languages, as well as those who use different 
    >> lingo.  The issue of vagueness in language is related.  A city is a 
    >> region, which may have a centroid point that is represented on a map.  A 
    >> user may wish to be vague about that, but that's a language issue, not 
    >> an ontology issue.
    >>At 11:06 AM 3/10/2003 -0500, Pete Haglich wrote:
    >>>We have adopted that in our current spatial ontologies, using the term 
    >>>"locus" because "location" had connotations to our customer.
    >>>The notion of "locus" has child subclasses of Point Locus, Linear Locus, 
    >>>Area Locus, and Volume Locus.
    >>>We find that the blurring of distinction between point and area is 
    >>>sometimes useful when discussing things like cities.  For some purposes 
    >>>they are usefully modeled as points, in other cases, it is more 
    >>>appropriate to reference the associated territory within the city limits.
    >>>On Friday, Mar 7, 2003, at 14:55 US/Eastern, Austin Tate wrote:
    >>>>The idea being that a neutral word like location which does not restrict
    >>>>the meaning to be only one of a "point" or "area" or "volume" and leaves
    >>>>nature of the "location" open can be useful to allow relationships to be
    >>>>stated to give real meaning.
    >>>Pete Haglich, ISX Corporation
    >>>Virginia Beach, VA
    >>>Mobile (757) 572-5913
    >Pete Haglich, ISX Corporation
    >Virginia Beach, VA
    >Mobile (757) 572-5913

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