1.4.1. Map Aspects

(Berendt et al. 1998) describe a typology of map types in terms of the aspects that they represent pictorially. Such aspects include everything that is depicted on a map, for example the geographic entities that are drawn and labelled, and the spatial relationships that amongst these. Their typology includes:

• Topographic maps - these aim to show the primary geographic characteristics of a landscape as precisely as possible (e.g. shapes of land, water areas, elevations, etc.)
• Thematic maps - these draw on topographic maps but describe qualitative information attached to a topographic basis (e.g. demographic information)
• General purpose city maps - These relax some of the constraints for precision in order to better emphasise labels and symbols for orientation in an urban environment.
• Schematic maps - these omit most of the topographic information to describe sequences and conjunctions of networks
• Sketch maps - these provide highly specialise ad hoc purposes omiting all but a few characteristics of the environment to depict the essential situational information relating to specific places.

Human factors

The important thing to recognise about this typology is that the aspects shown by a map relate to how the map is used, and so to human factors. Topographic maps need to be generic, so they make as few assumptions as possible about the map's use. City maps support orientation of people in a city. Here, the factors that are important are landmarks and street names since these are what the map user will look out for in trying to find their way around. When people travel on networks their movement is highly constrained. The way that they encounter space is by travelling along paths and changing between these at nodes. Hence, they do not need to know much about the space outside of the network. In providing maps to people navigating such networks much of the geometric information about the network can be relaxed. Only the topology of the network needs to be absolutely preserved. In each case, the point of abstract specific aspects is to reduce the amount of effort required to consult and follow the map, making the map use more efficient within the particular situation.

In this unit we will concern ourselves with schematic maps for transport and navigation and the types of aspects that these select. To give an example (Berendt et al. 1998) look at maps of transport networks. They list the aspects of the geographic entities these choose to represent, for example:

• Exact locations - the positions of stations within a city should be preserved as far as possible.
• Orientation between stations - the approximate orientation between stations in terms of cardinal directions should be maintained.
• Distance between stations - rough, as the crow flies distances between stations should be representative.
• Locations of start and end points - The ends of lines should coincide with with terminal stations