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

I'm not sure the distinction is all that helpful. We have two basic coordinate systems that are sufficient to identify places in the real world: civic (street) addresses and long/lat. Both can represent areas large and small, from a single room to a continent. It's obviously sometimes more difficult to map a current ___location to civic ___location, but not always. (For example, indoor ___location is often naturally civic.) On the other hand, descriptions such as "Starbucks in Chicago" are not terribly useful, given their ambiguity.

Thus, it comes down to 
- a region with a unambiguous coordinate system
- a set of attributes or links to those, possibly with a time validity indication

That's the "database record" or "unit of information exchange". Everything else can then be built on top of that.

Henning

On Nov 19, 2010, at 5:17 AM, Rob Manson wrote:

> 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 22:29:01 UTC