Adjacent-relation-based map zooming method
Map zooming is one of the most important operations in map reading process, especially to small displays or mobile information devices used in Location-Based Services (LBS) field. But existing map zooming methods, i.e. static linear zooming, static stepped zooming and dynamic zooming, mainly depend on metric relation, which ignore the effects of uneven spatial objects distribution to zooming operation. It leads redundant zooming and panning operation, and makes it difficult to read map in mobile information devices. This paper proposes a k.5-order adjacent relation model based on Voronoi diagrams and uses it to control the change of map information in the zooming operation. The main steps to realize adjacent-relation-based zooming include: classifying information, selecting generators, calculating and prestoring adjacent relations, calculating user's adjacent relation, Zooming-out or zooming-in based on user's adjacent relation. An experiment has been done and shows the method is feasible and efficient to improve existing zooming operation. The method also can be extended to desktop map zooming operation.