Geographic Information Systems: An Introduction, 3rd Edition

5.3 Representation of Time

Cognitive science has shown that the collection of historical data is essential to understand reality and to the acquisition of knowledge in general. Time is therefore a factor that concerns us deeply. It was studied by ancient Greek philosophers such as Plato and Aristotle, and it plays an important role in Einstein's theory of relativity.

Most things change with time, and the same applies to geographical data. Consider, for example, property data. New properties are continuously under development because of the division of existing properties; therefore, new geometry occurs. However, most changes are related to title ownership, with the resulting changes in attribute values. An example of an area in which extreme changes occur is the transport sector, with vehicles continuously changing position and where frequent on- and off-loading of goods change the attribute values that are linked to a vehicle.

In Chapter 3, we classified geographical objects into continuous and discrete phenomena, pointing out that there are phenomena in the transition between the two main classes. In the same way, we can classify events according to their frequency (Peuqet 1999):

• Continuous changes
• Frequent changes
• Sporadic changes
• Unique, one-time changes

Moreover, some events are cyclical (repeated at fixed time intervals) and others are chance happenings. Classification can also be influenced by the resolution of the time reference system. There is, for example, a big difference ...