(*) This work was partially supported by a grant Gu 293/8-1 from the Deutsche Forschungsgemeinschaft
(DFG), project “Datenbanken für bewegte Objekte” (Databases for Moving Objects).
Modeling and Querying Moving Objects in Networks*
Ralf Hartmut Güting
Victor Teixeira de Almeida
LG Datenbanksysteme für neue Anwendungen
FernUniversität Hagen, D-58084 Hagen, Germany
: Moving Objects Databases have become an important 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
. However, in many applications people or vehicles move along transportation net-
works. It makes a lot of sense to model the network 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 for static and moving network positions and regions.
In a highway network, example entities 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 seamlessly into the ADT framework to achieve a rela-
tively simple, consistent and powerful overall model and query language for constrained and
The field of
moving objects databases
has received a lot of research interest in recent years. This tech-
nology allows one to model in a database the movements of entities and to ask queries about such
movements. In some cases only time-dependent locations need to be managed, leading to the
abstraction, in other cases also the time-dependent shape or extent is of interest and we speak of
. Examples of moving points are cars, aircraft, ships, mobile phone users, terrorists, or
polar bears. Examples of moving regions are hurricanes, oil spills, forest fires, armies, tribes of people
in history, or the spread of vegetation or of an illness.
Some of the interest is spurred by current trends in consumer electronics. Wireless networking enabled
and position-aware (i.e. GPS equipped) devices such as PDAs, on-board units in vehicles, or even
mobile phones have become relatively cheap and are predicted to be in widespread use in the near
future. This will lead to many new kinds of applications such as location-based services. At the same
time a huge volume of movement information (sometimes called trajectories) will become available
and need to be managed and analyzed in database systems.