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GeoInformatics-7-2009
article figure 2: landmarks along spring street in melbourne. between landmarks and points of interest. the prior must be selected based on perceptive and cognitive principles. the latter is rather a list of a recommender service. deciding which landmarks are most useful is really based on the uniqueness of the landmark, and this can be determined by three main things; the landmark's meaning, its visual salience and where the landmark is located, relative to the decision point on the route, said matt duckham, senior lecturer in geographic information science at the university of melbourne. while computers can work out how far it is to the next interaction, humans find it much easier to use instructions that refer to places with meaning and that we can easily identify. matt duckham and stephan winter from the department of geomatics at the university of melbourne developed for sensis a model for incorporating landmarks into routing instructions that does not depend on the visual or geometric characteristics of individual buildings and streetscapes. instead the model relies solely on information about the types of landmarks present in the environment, in addition to the road network and route geometry. the motivation for this approach is primarily practical: these information sources are much more commonly available and easily accessible, for example in the form of a geocoded directory service. this model was applied on sensis yellow pages business directory and directories of points of interests from city maps. a set of cognitively motivated rules ranks categories for their typical landmarkness, and then helps to pick up the most salient landmarks along a particular route. the second step considers also the struc- ture of the route, such that landmarks are chosen at locations where the traveler has to turn, or along long segments for confirmation. while more and more categories are added, and rules are tuned, routing by whereis.com has already access to 170,000 landmarks nationwide. let us study an example. figure 2 shows the ranked landmarks along one street segment that are currently available in whereis.com to produce routing directions. figure 3 shows route directions along this street segment. only two landmark candidates were selected and included in the directions, and both at strategically important locations along the route. stephan winter and matt duckham, department of geomatics, the university of melbourne, australia. michelle robinson, sensis pty ltd, australia figure 3: route directions with selected landmarks along spring street. latest news? visit www.geoinformatics.com 59 october/november 2009
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