Conceptual Aspects: How Landmarks Can Be Described in Data Models - Landmarks: GIScience for Intelligent Services - page 126

Fig. 4.2 A switch in spatial granularity from stations to exits (or other elements) of stations. Map
copyright OpenStreetMap contributors, used under CC BY-SA 2.0

4.3 Landmarks in Geographic Data Structures

Our conceptual model requires data models capable to represent the landmarkness
of entities of any spatial granularity while representing this landmarkness in a
context-dependent way. In this section we will review existing data models for their
compliance, and discuss shortfalls in particular cases.

4.3.1 POI Data: Substitutes for Landmarks

Popular web mapping services, car navigation services or mobile location-based
services have internal data structures for storing points of interests (POI), and
accordingly also standards for the description and exchange of POIs exist . 6 We
have discussed already the fundamental differences between landmarks and POIs,
but here we come back to POI since they appear to be used in lack of the more
appropriately suited landmarks in service-generated place and route descriptions.
POIs are stored as traditional Geographic Information System layers containing
categories of geographic objects such as places of interest, businesses, transit
stations, mountains, parks and golf courses. This arbitrary mixture of categories,
by the way, are just the default layers taken from a prominent search engine's
webmapping application. These layers can also be expanded by further categories,

6 http://www.w3.org/2010/POI/ , http://openpoi.ogcnetwork.net/ , last visited 3/1/2014.