Graph Drawing Techniques for Geographic Visualization

Geovisualizers often need to represent data that consists of items related together. Such data sets can be abstracted to a mathematical structure, the graph. A graph contains nodes and edges where the nodes represent the items or concepts of interest, and the edges connect two nodes together according to some associational scheme. Examples of graph data include: network topologies; maps, where nodes represent towns and edges represent roads; and social diagrams where people are the nodes and edges represent some relationship between people, for instance, that they are friends. A good layout allows users to more easily investigate the data when performing tasks such as following paths, seeing clusters of closely related nodes and discovering general structures in data. Laying out graphs by hand is time consuming, however there are a number of proven graph drawing methods which can be used to automatically visualize the data.