- From: Frans (Geodan) <frans.knibbe@geodan.nl>
- Date: Fri, 20 Feb 2015 13:23:07 +0100
- To: public-sdw-wg@w3.org
- Message-ID: <54E7272B.7090204@geodan.nl>
Some comments inline...
On 2015-02-19 17:25, Karl Grossner wrote:
> "All these things are debatable, but rather than debate them it would
> be good to have agreed upon semantics." Ah, but hard to see how
> agreement is reached with or without debate!
Oops, it was certainly not my intention to speak out against debate. I
think I wanted to say that it would be good for the debate to have some
solid and useful results, rather than have an open ending. In this case,
it would be good to end up with agreed upon definitions of our basic
concepts.
>
> I have swum these murky waters for a little while, even wrote papers
> titled "Event Objects for Spatial History" then "Event Objects for
> Placial History."
>
> The problem is that place and location are used interchangeably as
> answers to 'where?' and their common definitions are circular. I have
> found it easiest to think of spatial data as formal descriptions of
> locations (on or near the earth surface for our immediate purposes) --
> discrete portions of space described by geometry. Place suggests an
> occurrence, and place attributes ("placial data") are many. They are
> normally referred to by toponyms. The geometry (spatiotemporal
> context?) of places famously change over time (even disappear and
> re-appear, e.g. Poland), are non-existent (Atlantis), unknown or
> uncertain (ancient places referred to in texts), vague (Central
> London), disputed (Tibet), dynamic (the deck of a ship), and so on.
> Other attributes of Place are entirely experiential and subjective
> (the NYC of my youth vs. your experience of it; Ed's example of where
> "my keys" are). These constitute a host of unsolved
> representation/computation problems.
I like the idea of using 'where' in a definition of 'location' or
'spatial entity'. At least it can help to avoid circular definitions.
Something like: "a location (spatial thing) is something than can be
given as an answer to a 'where?' question"... But that is not good
enough, because something like the distribution of annual rainfall is a
spatial thing in my book, but since it is not located somewhere (it is
everywhere, a continuous phenomenon), it can not be an answer to a where
question.
As for the experiential and subjective nature of spatial data, I think
adopting the AAA-principle of the semantic web (Anyone can say Anything
about Anything) can be helpful. If a data publisher asks the question
"Are my data spatial?", the return question could be "Do you want them
to be?"
>
> I'm guessing the "spatial data" in the list was meant to refer to all
> of that, and is common usage -- although I prefer "spatiotemporal," or
> even better, "geographic."
The main difference that I perceive between 'spatial' and ''geographic'
is that geography is tied to earth, or the earth's surface, because of
the 'geo' prefix. At some point such a restriction may have to be made,
but I think it can better be applied to a lower level concept like
'geometry' (because geometry is expressed in a terrestrial coordinate
reference system).
> I don't understand what is meant by "spatial context" in this
> conversation but think it does no harm to add it as criteria for
> considering use cases. I also think we will arrive at a working
> extensional definition of spatial data by considering all the use
> cases people consider as concerning spatial data or spatial context.
Or we could try to use the existing definitions in use in the body of
OGC standards. After all, a lot of time and thinking by spatially minded
people went into them.
Greetings,
Frans
>
> best,
> Karl
>
>
> ------------------
> Karl Grossner, PhD
> Digital Humanities Research Developer
> Center for Interdisciplinary Digital Research (CIDR)
> Stanford University Libraries
> Stanford,CA US
> www.kgeographer.org
>
>
> ------------------------------------------------------------------------
>
> I think that the question whether data are spatial data largely
> depends on the data publisher. The designation “Greater London”
> could be published as a text label, in which case it is not
> spatial data. It could also be published as a toponym, in which it
> is spatial data.
>
> This discussion seems to point at an important requirement for our
> work, which may or may not be derived from use cases, but still is
> important: We need clear and universal semantics.
>
> What makes a thing spatial? Does it have to have geometry? Does it
> have to have three dimensions? Does it need to be a terrestial
> object? Does it need to be non-fictional? All these things are
> debatable, but rather than debate them it would be good to have
> agreed upon semantics.
>
> At the moment, there are some definitions out there on the
> semantic web. For example, the Location Core Vocabulary
> <http://www.w3.org/ns/locn> defines the concept 'location'.
> Unfortunately the definition is self-referencing: “any location,
> irrespective of size or other restriction”. In other words, it is
> very open to interpretation. Is “Paris” a location (knowing that
> there are multiple locations with that name)? Is Atlantis
> (fictional) a location? Is Olympus Mons (on Mars) a location?
>
> GeoSPARQL <%28http://www.opengis.net/ont/geosparql> has
> definitions for the concept 'SpatialObject': “..everything that
> can have a spatial representation” (unfortunately the 'spatial
> representation' part is undefined) and 'Feature': “..equivalent to
> GFI_Feature defined in ISO 19156:2011”. Unfortunately GFI_Feature
> as defined in ISO 19156:2011 is not a web resource and ISO
> 19156:2011 is not an open standard (because you have to pay for
> it). But it's a start...
>
> Greetings,
> Frans
>
>
> On 2015-02-19 11 <callto:2015-02-19%2011>:50, Ed Parsons wrote:
>
> This is a great discussion and I think it is central to the
> potentially difficult overlap between the two community
> perspectives.
>
> I'm sure Josh will chip in but I do think we need to recognise
> that we need to include spatial information for which it is
> not possible to define a geometry or have linked to as an
> attribute - This I think is what Josh means by context, I am
> writing this email from a location within "Central London"
> although there is not a canonical geometry that represents the
> shape of central London.
>
> This is an example of what Mike Goodchild calls a Platial
> Problem !
>
> This must be in scope, does the current wording around spatial
> information accommodate it ?
>
> Ed
>
>
> On Thu Feb 19 2015 at 10:26:55 Andrea Perego
> <andrea.perego@jrc.ec.europa.eu
> <mailto:andrea.perego@jrc.ec.europa.eu>> wrote:
>
> Andreas's mail gives me the opportunity to explain the
> objection I
> raised during the call [1] about the proposal of adding
> "spatial
> context" into scope question #1 [2].
>
> My main concern is that the use of "spatial context" in
> the scoping
> question may be confusing, and probably unnecessary.
>
> In my understanding, spatial context is specified through
> spatial data
> - i.e., it denotes one of their possible uses. So,
> "spatial data"
> should be inclusive enough - it would cover spatial data
> as a whole,
> irrespective of their use.
>
> Thanks!
>
> Andrea
>
> ----
> [1]http://www.w3.org/2015/02/18-sdw-minutes.html
> [2]http://www.w3.org/2015/spatial/wiki/Scope_questions_and_Requirements
>
> On Wed, Feb 18, 2015 at 10:10 PM, Andreas Harth
> <harth@kit.edu <mailto:harth@kit.edu>> wrote:
> > Hi,
> >
> > the issue I had with the term "spatial context" is that
> I did not know
> > what the "context" part was supposed to mean.
> >
> > If I understood Josh correctly, he mentioned that a
> geometry,
> > a place description or a spatial feature should be
> referenceable
> > in data.
> >
> > If "spatial context" does mean that, I'm fine with the
> phrasing of
> > the scoping question.
> >
> > Cheers,
> > Andreas.
> >
>
>
>
> --
> Andrea Perego, Ph.D.
> Scientific / Technical Project Officer
> European Commission DG JRC
> Institute for Environment & Sustainability
> Unit H06 - Digital Earth & Reference Data
> Via E. Fermi, 2749 - TP 262
> 21027 Ispra VA, Italy
>
> https://ec.europa.eu/jrc/
>
> ----
> The views expressed are purely those of the writer and may
> not in any circumstances be regarded as stating an official
> position of the European Commission.
>
>
>
>
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Received on Friday, 20 February 2015 12:23:40 UTC