A generic data model for moving objects
The current data models for managing moving objects can be classified by environments such as road network or indoor. Road network is for moving objects like cars, taxis, and indoor is for humans moving inside a building. However, each model addresses only one specific case. To represent the complete movement for a moving object, especially a human who can move inside a building, walk on the pavement outside, drive the car on the road, and use the public vehicles (bus or train), more than one model are needed. In this paper, we propose a generic data model for representing moving objects that encapsulates multiple environments so that the database system only needs one model to manage all the data. Abstractly, the method is to let the space where an object moves be covered by a set of so-called infrastructures and to represent the location data by referencing to these infrastructures. Each infrastructure provides an environment for moving as well as its available places. It consists of a set of infrastructure objects. For example, road network is a kind of infrastructure and indoor environment is also a kind of infrastructure where the roads, streets and rooms are infrastructure objects. Besides, transportation modes (e.g., Car, Bus, Walk) are seamlessly integrated into the model to enrich moving objects with semantic data, making the representation more expressive than only focusing on location data. Because for humans’ movement, it is necessary to know both where and how. In addition, our model represents the location in a multiresolution way where both imprecise and precise data is managed. With the generic model, a complete trajectory covering multiple environments can be represented. The newmodel is carefully integrated with the type system and the framework of operators provided in earlier work for free space and for road networks. In this way, a powerful set of generic query operations is inherited and available for querying, together with extensions dealing with the new infrastructures and transportation modes. We demonstrate these capabilities by formulating a set of sophisticated queries across all infrastructures.
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