Re: Action 10 - What Is A POI? - "Place-Oriented Information"?

Hi Dan,

hrm...surely "Place Oriented Information" is a more confused/confusing
term.  I agree with the differentiation that Gary highlighted between
Location and Place.  And I agree with what I think you're trying to get
at about the separation between "the territory" and the "aspects" of
"the map".

But I think it's pretty clear that the group has included all types of
"things" that can be represented by POIs including objects that move in
space and time (e.g. people, cars, etc.).  Blurring the concept of Place
with things like people and cars just doesn't make sense.

That map/territory distinction is really useful though.  POIs are just
meta data/records that link arbitrary things to specific Locations
(possibly within a specific window in time).  The Location is a real
thing (represented in some coordinate system).  The arbitrary thing may
or may not be real (e.g. a Place, a person, a car or even a reported
incident or an opportunity).  But the POI (in this #poiwg context) is
just a way of linking these.

Because it's such a convenient concept people may often confuse it with
or collapse it down to the thing it signifies...but in our context this
abstract separation is key.

In our AR applications we are generally presenting POIs to users...but
not because they actually care about the POI itself...but the "thing"
that it re-presents.


roBman


On Fri, 2010-11-19 at 10:43 +0100, Dan Brickley wrote:
> On Wed, Nov 10, 2010 at 10:11 AM,  <gary.gale@nokia.com> wrote:
> > Based on what's been discussed on the public mailing list, I've drawn
> > together a definition and description of what constitutes a POI. This will
> > no doubt be cause for much discussion and debate but we need a good starting
> > point to drive and frame the discussion ...
> > Best
> > G
> >
> > What Is A POI?
> > Wikipedia defines a POI as a Point Of Interest ... a "specific point
> > location that someone may find useful or interesting". But for the purposes
> > of this Working Group, we need a more subtle and complex definition.
> > A POI is part of a loosely coupled and inter-related geographical terms,
> > comprised of (in generalised order of scope and granularity) Locations, POIs
> > and Places.
> > Location
> > A Location is a geographical construct; a physical fixed point on the
> > surface of the Earth. It could also be used to describe a fixed point on the
> > surface of another celestial body but for the purposes of this Working
> > Group, we'll restrict the scope to terrestrial geographies. A Location is
> > described by a centroid (a longitude and latitude in a widely adopted
> > system, such as WGS-84) and an extent, either a Minimum Bounding Rectangle
> > or a vector set. A Location is temporally persistent, it does not generally
> > change over time.
> > POI
> > A POI is a human construct, describing what can be found at a Location. As
> > such a POI typically has a fine level of spatial granularity. A POI has the
> > following attributes ...
> > 1. A name
> > 2. A current Location (see the commentary below on the loose coupling of POI
> > and Location)
> > 3. A category and/or type
> > 4. A unique identifier
> > 5. A URI
> > 6. An address
> > 7. Contact information
> > A POI has a loose coupling with a Location; in other words, a POI can move.
> 
> I like the idea of breaking out Location, and Place, and these kinds
> of fields seem the right kind of thing. But I'm not yet comfortable
> with POI itself. It's a slippery notion!
> 
> Perhaps the key distinction here isn't quite between 'geographical'
> and 'human' constructs, but between terms that directly name aspects
> of the world, versus terms that name kinds of information about that
> world. The former might range from very geographical, objective,
> physical things to more human constructs such as neighbourhood. The
> latter makes explicit a level of indirection, and allows the
> representation to be talked about explicitly. I think this is why the
> concept of POI is somehow slippery when we try to pin it down.
> 
> For me, POI is much more in the latter case. "Count questions" (How
> many Xs...?) can help flesh out the difference.
> 
> We can sensibly ask:
> 
> * How many streets, churches, fire hydrants, mountain tops, traffic
> blockages, classical music concerts on next saturday, vegan
> restaurants; canals or houseboats are there in [some defined notion
> of] Amsterdam right now?
> 
> Each of these definitions is slippery in a different way, and
> different agencies, groups etc might define them differently. Yet the
> questions remain primarily about the world, albeit expressed using
> imperfect, debatable terminology that might need clarifying.
> 
> If we assume some working consensus of specified definitions (active
> churches in the x,y and z faiths; fire hydrants serviced by the civic
> authority and known to be recently tested; traffic blockages reported
> in the last hour and believed to be still affecting drivers but not
> bikes;  etc etc.), each of these questions has factual answers. Now we
> would get different answers depending on who we ask, which database we
> query, how much money or time we spend asking, what our policy is
> towards risk and noise in the data etc., or the exact notion we're
> querying for. But the basic scenario is factual questions about the
> world, answered in loose or precise form depending on context. Note
> that as we get more precise ("reported in the last hour (and not
> reported as fixed subsequently)"), characteristics of information and
> communication start to sneak into the scenario. This is a good thing -
> it means we have useful work to do!
> 
> If we ask instead:
> 
> * how many POIs are there in [some defined notion of] Amsterdam right now
> 
> I don't believe that really has a direct factual answer, without one
> crucial qualifier: we need to say which collection of information
> we're talking about. How many traffic blockage POIs came back in our
> last database lookup? How many Fire Hydrant POIs were described in the
> appendix to the 2010 hydrant QA report? How many upcoming classical
> concert POIs were attached to that that last email newsletter I
> received, or embedded in the concert hall's iCalendar or RSS/Atom
> feed? How many POIs were stored on the DVD I've just bought entitled
> 'Mountaintops of the Western Netherlands?". That's a different
> numerical question to the question of how many mountains are there in
> the Netherlands, although the answers are likely to be related. And in
> this last case, zero-ish.
> 
> The same worldly questions and themes crop up in both stories, but
> when we talk about POIs we're emphasising the information about the
> world as an artifact of direct interest, and in our case technical
> standardisation; rather than a transparent means-to-an-end, where the
> end is 'information about the world'.
> 
> By making this indirection explicit, that POIs are informational
> entities, I think this eases one of our biggest conceptual problems:
> how we deal with different levels of detail. From the example on
> weds's call talking about a building, and Gary's desk in the building,
> and even some item on that desk of Gary's in that room in that
> building in that street. And for the AR guys, for professional GIS,
> architecture and city planners alike, these distinctions matter. These
> are all identifiable worldly entities, potentially of interest,
> potentially described in a variety of standard computer formats. It
> makes sense to ask factual questions like 'how many rooms in the
> building', but not 'how many POIs'; we can ask 'how many POIs
> describing things in that room are there in this particular dataset?'
> or 'give me POIs at the granularity of DesktopObject for this area'.
> 
> This is all a longwinded way of suggesting that "POIs" are better
> thought of as aspects of the *map* rather than the *territory*.
> However the usual expansion of POI as "Point of Interest" hides this,
> and makes us think of POIs as objective characteristics of the world
> around us, countable, comparable, etc. without being set in the
> context of some description, dataset or map.
> 
> If we think of POI as "Place-Oriented Information" it makes their
> information-dependency much more explicit. I suspect this will help us
> think through mashup-oriented issues like "ok, we have one restaurant
> but 5 POIs in our system that relate to it; one's a photo, two are
> reviews, one comes from a health inspector's report and another is a
> 3d building plan". The "POIs" (also pieces of information...) all
> relate to the same spatial zone, but they carve it up quite
> differently; some treat it (the photos) as an area that reflects
> light, some as a service or organization/business that can be
> reviewed, paid money, sued, and one as a building occupying physical
> space (perhaps with others also inside it).
> 
> We want a POI standard that allows all these kinds of information
> about "the restaurant" to be brought together to serve end-user
> scenarios, and to make life easier on the technologists who'll
> facilitate this. But we also don't want our POI standard to be
> fiendishly rich, modelling fine-grained distinctions explicitly such
> as "business" versus "building" within the W3C spec. I expect to see
> systems that do draw those distinctions to be able to answer "how many
> businesses?" "how many buildings?", "how many businesses in this
> building?" kinds of question. I hope they'll be able to answer them in
> part from indexing W3C POI descriptions and other extension data or
> linked files (CityGML etc). But the more I think about it, the more I
> reckon we should reserve POI as a technical term for talking about
> those underlying data items used to answer questions, display maps and
> AR views and so on, rather than talk as if POIs are actually out there
> in the world. The actual points of interest are of course out there in
> the world; pieces of place-oriented information live in our computers,
> phones, files and data networks.
> 
> cheers,
> 
> Dan
> 
>

Received on Friday, 19 November 2010 10:18:36 UTC