Database Reference
In-Depth Information
1
Trajectories and Their
Representations
Stefano Spaccapietra, Christine Parent, and Laura Spinsanti
1.1 Introduction
For a long time, applications have been using data about the positions of the
moving objects they are interested in. For example, city planning applications,
in particular in the transportation and traffic management domains, have been
observing and monitoring traffic flows to capture their characteristics, namely
their importance and localization, with the aim to build better models for traffic
regulation and to identify solutions for future development of the existing road
network. Sociologists have also been examining the movement of cars equipped
with GPS, focusing on individual cars rather than traffic flows, to understand the
habits of their drivers. In the logistics domain, applications have been monitor-
ing the localization of the parcels during their transportation from their source
locations to their destinations. These applications use the data both to be able to
locate a parcel at any time and to optimize the performance of the transporta-
tion and distribution strategy. Similar concerns rule the management of data
tracking airline passengers and their luggage. Ecologists have been observing
animals and, whenever possible, tracking them via transmitters and satellites,
mainly to understand animals' individual and group behaviors. Nowadays many
enterprises are looking to extract information about their potential consumers
out of the tracks left by their smartphones, electronic tablets, or access to social
networks such as Flickr and Foursquare that record the geographic position of
their users.
Traditionally, data about movement have been captured using static facilities,
for example, sensors producing traffic flow measures or detecting an animal's
presence. Data acquisition facilities changed drastically with the availability of
embedded positioning devices (e.g., GPS). Traffic data, for example, can now
be captured as the sequences of positioning signals transmitted by the cars' GPS
all along their itineraries.
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