Database Reference
In-Depth Information
spatial event: An
event
having a specific position in space, which is not necessarily fixed
during the time of event's existence. An event may be considered as spatial or not depending
on the spatial scale of the analysis.
spatio-temporal position: A position of a moving object at a given instant, represented
by a tuple containing at least two data (instant, point), where point is a 2D (
x,y
)or3D
(
x,y,z
) spatial point. Other features may complement the tuple: spatio-temporal data such
as instant speed or stillness, direction, rotation, acceleration, or semantic annotations that
have been captured or inferred such as activity or transportation means.
time-dependent data type: A data type that represents data whose values change over
time. For example, the location of a moving object is represented by a time-dependent
point.
trajectory: A part of the movement of an object that is of interest for a given application
and is defined by a time interval that is included inside the lifespan of the object. The two
extreme spatio-temporal positions of the trajectory are referred to as its Begin and End
positions.
trajectory behavior: A trend characterizing some
trajectories
. From a data management
viewpoint, a trajectory behavior is a Boolean predicate on trajectories that can rely on
any characteristic of the trajectories (e.g.,
spatio-temporal positions
,
episodes
); contextual
data linked to the trajectories (e.g., attribute values of geo-objects linked to stop episodes);
and relationships to geo-objects, events, or other moving objects. Examples are the Loop
trajectory behavior and the Flock trajectory behavior. It is also referred to as trajectory
pattern
.
trajectory clustering: The process of
clustering
asetof
trajectories
into homogeneous
groups according to one or more properties characterizing them. These properties can be
spatial (e.g., begin point, end point, length), temporal (e.g., begin time, end time, duration),
or dynamic (e.g.,
spatio-temporal position
, direction, speed at some instants).
trajectory collective behavior: A
trajectory behavior
that bears on a set of trajectories,
that is, a Boolean predicate
p
(
S
)where
S
is a set of trajectories containing more than one
trajectory. An example is the Flock trajectory behavior.
trajectory compression: The task of reducing the size of the data stored for a
raw trajec-
tory
by removing as many
spatio-temporal positions
as possible without warping the trend
of the trajectory or distorting the data set.
trajectory data mining: A specific type of
data mining
process applied to a set of
trajec-
tories
. It is also referred to as mobility data mining.
trajectory data warehouse: A specific type of
data warehouse
that stores
trajectory
data.
trajectory database: A specific type of
database
that stores
trajectory
data. It is also
referred to as a moving object database.
trajectory individual behavior: A
trajectory behavior
that bears on a trajectory, that is, a
Boolean predicate
p
(
T
)where
T
represents a trajectory. An example is the Loop trajectory
behavior.
trajectory interpolation: Reconstruction of the most probable
spatio-temporal positions
of a moving object between two recorded spatio-temporal positions.
unit representation: A relational implementation of the
sliced representation
where a
time-dependent value is stored as a set of tuples, each tuple representing a slice.
vague spatial object: A spatial object whose extent is represented by the spatial extent of
the kernel part, which is certainly part of the object, and the extent of the conjecture part,
