Action 10 - What Is A POI?

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 ...



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.


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.


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. When this occurs, the loose coupling with the previous location is removed and, providing the POI continues to exist, it is then coupled with its new Location. This can happen when the human activity at the POI relocates, such as when your local coffee shop relocates to a new address. It's still your local coffee shop, it's now found at a different Location.

A POI has temporal boundaries; it starts when the human activity at that Location commences and ends when human activity ceases, such as when a company or organisation goes out of business.


A Place is also a human construct and typically has a coarse level of spatial granularity. Places are typically larger scale administrative constructs, either informally or formally defined. Countries, States, Counties, Districts, Neighbourhoods and postal codes or telephone area codes are all Places. Places are also informally or colloquially defined, such as the Home Counties in the United Kingdom and The Bay Area in the United States.

Places have spatial relationships; with parents, children, adjacencies and "contained by" semantics. Places also have the same attribute set as POIs, although with differing interpretations based on scale; for example, the address of a Place or its URI would refer to the address of the administrative or governing body of the Place.

A Place typically contains multiple POIs and can also be coterminous with a POI. In the former case, a Place, such as a city or a neighbourhood, will contain multiple POIs. In the latter case, a Place and a POI will occupy the same position and extent, such as in the case of Yellowstone National Park, which is both a Place and a POI.

Gary Gale
Director, Ovi Places Registry, Nokia Gate5 GmbH
Invalidenstr 117, 10115 Berlin, Germany
UK: +44.7508.000336 | DE: +49.1515.5150909<>

Received on Wednesday, 10 November 2010 09:12:06 UTC