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Re: Do we need to reference all three sets of spatial relations from GeoSPARQL in BP14?

From: Ed Parsons <eparsons@google.com>
Date: Tue, 14 Mar 2017 14:03:37 +0000
Message-ID: <CAHrFjckESi+JBW1wi3uTi15RH6ma=gut8ad67jVR+aO1d1F2QQ@mail.gmail.com>
To: Jeremy Tandy <jeremy.tandy@gmail.com>, SDW WG Public List <public-sdw-wg@w3.org>
I tend to agree with 1) stronger guidance on the commonly used "simple"
relationships and given this 2) not mentioning the others...

Ed


On Tue, 14 Mar 2017 at 09:45 Jeremy Tandy <jeremy.tandy@gmail.com> wrote:

> Hi-
>
> BP14 [1] is now updated (and probably too large and unwieldy in its
> current form - we plan to discuss refactoring in Delft during the general
> BP doc restructuring discussion).
>
> However, one quick question might be resolvable before Delft.
>
> In "Possible Approach to Implementation" BP14 talks about the types of
> links that might be used. Section "2. Spatial relationships" discusses
> topological relationships. It states:
>
> > [GeoSPARQL] defines three families of topological relationships (simple
> features, Egenhofer and RCC8) all of which are based on the DE-9IM
> <https://en.wikipedia.org/wiki/DE-9IM> pattern, which specifies the
> spatial dimension of the intersections of the interiors, boundaries and
> exteriors of two geometric objects that may be 2-dimensional (e.g. area),
> 1-dimensional (e.g. linear) or 0-dimensional (e.g. point).
>
> ... and ...
>
> > Details of the Simple Features, Egenhofer and RCC8 (Region Connection
> Calculus <https://en.wikipedia.org/wiki/Region_connection_calculus>)
> topological relations families are provided in [GeoSPARQL] section 7
> Topology Vocabulary Extension.
>
> BP14 identifies that the simple features relationship family is the most
> commonly used. The [exam] questions for you are:
> 1/ should we be stronger with the guidance on using simple features
> relationships over those from the other families?
> 2/ do we even need to mention the other two families? (to my untrained
> brain, they're just confusing!)
>
> Thanks in advance.
>
> Jeremy
>
> [1]: http://w3c.github.io/sdw/bp/#entity-level-links
>
-- 


*Ed Parsons *FRGS
Geospatial Technologist, Google

+44 7825 382263 @edparsons
www.edparsons.com
Received on Tuesday, 14 March 2017 14:04:20 UTC

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