GIS Files 2: Geographical data

2.5: Looking at multiple layers (2)

Identifying change over time

Another benefit of mixing and matching different layers is that by combining mapping for the same area surveyed at different times, you can identify any changes. The example below shows the changes that have occurred as the coast has been significantly eroded over time. The green line is the current position of the cliff.

These are just simple examples of how a different message can be portrayed within a GIS by showing a mixture of feature layers. The most sophisticated GIS users are likely to be working with hundreds of layers, enabling them to create any kind of map display for a particular geographical location.

Now things start to get more exciting – GIS not only revolutionises the usefulness of map information, by allowing it to be shown in many different combinations, it also takes us beyond the realm of the flat, planar view of the landscape. The next section looks at 3-D mapping using GIS: Section 2.6 – The third dimension.

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