GIS Files 3: Adding real-world information

3.1: The attributes of map features (1)

What are attributes?

The maps shown in GIS are intelligent – the features know their own identity. How?

In chapters 1 and 2 the ways in which geographical information can be loaded into a computer and displayed in a GIS have been described. We now move on to show how this information can be used. The term attribute describes any piece of information about an object that can be stored in addition to its geographic properties. For instance, a road may have a number, a name, a maximum width, a speed limit and so on. GIS can work with this descriptive attribute information to create intelligence way in advance of what can be achieved by placing text on a paper map.

With GIS you are no longer restricted by how many text descriptions can be fitted into the available space to convey information about the objects in an area. Tabular information can be stored about each of the objects just as in a database, so allowing an almost infinite array of attributes to be recorded. All GIS have simple tools that allow the interrogation of the features. Hence, by using your mouse to click on an object, a full set of attributes can be displayed without that information having to be on screen all the time. The object of interest can be identified by the visual map graphic and then that object can tell you its own attributes. Which is very clever stuff...

Move your mouse over the graphic to see the attributes that are associated with the house and the road.

< 3: Introduction | 3.1: The attributes of map features (2) >