GIS Files 4: Putting it all in a system

4.4: Show me the way to go (1)

Network analysis

One of the most far-reaching applications of GIS is in network analysis. Network analysis is the mathematical processing of the geometry of a link/node layer, enabling the identification of all possible routes around that network, along with the distances and times involved. Put simply, this means that, using an accurate road data layer, the computer can identify possible routes between two locations and calculate the shortest.

OK, now we have definitions out of the way let's remember what we covered in section 2.7. Way back then, we discussed the concept of link-node topology and how important it is to have the data structured correctly (that is links joining at nodes with no gaps). In order to carry out network analysis you need a link-node data layer of line features representing a real-world network (for example, a road network); only then is it possible to model movement around that network.

The simplest example of network analysis is to choose two points on the network and ask the GIS to calculate the shortest path between them.

• A - B
• A - C
• A - D
• B - C
• B - D
• C - D

This basic concept can be used to help build navigation systems and to plan distribution services.

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