Introduction:What Landmarks Are, and Why They Are Important - Landmarks: GIScience for Intelligent Services - page 6

Fig. 1.3 A ranked list of
landmarks
the context of geographic information [ 39 ] . They are standard elements in spatial
databases: A typical GIS contains database layers of (representations of) buildings
and roads, and gazetteers of geographic names contain representations of mountains.
According to prototype theory each of these categories will have typical examples
as well as less clearly assigned entities. When it comes to these boundary cases in
categorizations, people start to disagree or become uncertain. Is a single garage, a
shed, or a kennel still a building ? Is a laneway, a mall, or a trek still a road ? Is a hill
a mountain ? Is Uluru a hill or a mountain? These questions are important for map
makers and database administrators alike since they decide about the cleanliness of
their products. A producer does not want to have a product with information many
people disagree about. These questions also decide about the ability to compare
different map sources or databases. Map updating, for example, should not merge
datasets of varying semantics. It has even been shown that these classifications can
vary across languages and cultures [ 29 , 30 ] . Thus, there is no definite answer to the
question which object is a landmark and which is not. Landmarks are countable but
are not finite.
There are other reasons adding evidence to this conclusion. For example, the
world is constantly changing, and over time it can change whether a geographic
object is a landmark or not. The first skyscraper in Chicago was a landmark, at
least for some time, until it became one of many and others were more outstanding.
Accordingly, classifications of objects can be made only for a certain time. But even
at a snapshot in time we have already seen it is impossible to provide a complete
list. Now we know why. It is because of graded membership. Additionally this grade
of membership to the landmark category depends also on the context. For example,
a city looks very different by night than by day, and landmarks in night scenes
may be quite unimpressive in daylight. Or consider a café that became special for a
couple because it is the place where they first met. It is one of the locations in the
city they refer to when they explain other locations to each other. For the two of them
it has become a landmark they share even if this is one of many cafés in that street.
For others, especially those who never visited the café, it is not. The New York City
Apple Store (Fig. 1.4 a ) may have the meaning of a landmark for people of some