1.4.3. Route maps
Route maps abstract aspects of road networks that relate to the way people encounter space while driving. There are two particular types of feature here, the paths of the network that are transited and the places where the driver needs to make decisions, such as turning. Unlike for the underground map, it is much harder when driving to identify a these features and make the correct decisions at turning points. Hence route maps need to include a set of aspects that make this clear to the driver.
Landmarks
One important feature that needs to be shown on route maps is landmarks. Along a path this tell the driver that they are on the right route and how far along the path they are and so how soon they will need to make a turning decision. At decision points they mark the point itself, e.g. "At the post office turn left.", and disambiguate between different possible choices of paths, making the turning instruction easier to understand, e.g. "Turn left under the bridge.".
Landmark corridors
(Elias 2002) has looked at how landmark information can be extracted from digital landscape models and presented as route corridors for drivers. The graphic below illustrates the processes she uses to generate the maps.
- Compute a route between the desired start and destination points of the map user.
- Identify landmarks within a buffer of this route (e.g. 20 metres).
- Simplify the shapes of the landmarks and the route for the final presenation. As you can see in the final map the generalisation of the shapes of landmark buildings is strongly dependent on the uniqueness of their outline. Buildings with characteristic shapes are retained so as to better communicate the visual aspects of the building to the driver.
LineDrive
(Agrawala et al. 2001) has produced a system called LineDrive that describes routes even more abstractly, as a sequences of lines. The image below shows and example of the output of LineDrive.
You can play with LineDrive yourself of the the MSN map site. Press the "Get Directions" button to define a route and be sure to check the "LineDrive" option for the map style. What types of aspects do these maps present?
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