Modeling and querying moving objects in networks
Moving Objects Databases have become an im portant research issue in recent years. For modeling and querying moving objects, there exists a comprehensive framework of abstract data types to describe objects moving freely in the 2D plane, providing data types such as moving point or moving region . However, in many applications people or vehicles move along transportation net- works. It makes a lot of sense to model the netw ork explicitly and to describe movements relative to the network rather than unconstrained space, because then it is much easier to formulate in queries relationships between moving objects and the network. Moreover, such models can be better sup- ported in indexing and query processing. In this paper, we extend the ADT approach by modeling networks explicitly and providing data types fo r static and moving network positions and regions. In a highway network, example en tities corresponding to these data types are motels, construction areas, cars, and traffic jams. The network model is not too simplistic; it allows one to distinguish simple roads and divided highways and to describe the possible traversals of junctions precisely. The new types and operations are integrated seamle ssly into the ADT framework to achieve a rela- tively simple, consistent and powerful overall model and query language for constrained and unconstrained movement.
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