By Rolf A. de By
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Maps and databases can be considered static models. At any point in time, they represent a single state of affairs. Usually, developments or changes in the real world are not easily recognized in these models. 2. The real world and representations of it models address precisely this issue. They emphasize changes that have taken place, are taking place or may take place. Dynamic models are inherently more complicated than static models, and usually require much more computation to obtain an intuitive presentation of the underlying processes.
We call it such because the representation will have certain characteristics in common with the real world. , the model, instead of the real world. The advantage of this is that we can ‘play around’ with the model and look at different scenarios, for instance, to answer ‘what if’ questions. We can change the data in the model, and see what are the effects of the changes. Models—as representations—come in many different flavours. In the GIS environment, the most familiar model is that of a map. A map is a miniature representation of some part of the real world.
Increasingly, maps lose their role as data storage. This role is taken over by (spatial) databases. What remains is the visualization function of maps. 2. 3 Databases A database is a repository capable of storing large amounts of data. It comes with a number of useful functions: 1. , it allows concurrent use, 2. , it supports storage optimization, 3. , it supports data integrity, 4. , it has a query facility, 5. , it offers query optimization. Databases can store almost any sort of data. 1. A database may have many such tables, each of which stores data of a certain kind.
