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SPATIOTEMPORAL DATABASES

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Title: SPATIOTEMPORAL DATABASES


1
SPATIO-TEMPORAL DATABASES
  • Intro

2
  • Space by itself, and time by itself,
  • are doomed to fade away into mere shadows,
  • and only a kind union of the two will preserve an
    independent reality.
  • (Albert Einstein)

3
Spatial and Temporal Databases
  • In many activity areas, space and time are
    essential aspects. The applications have to
    process and query data that represents spatial
    and / or temporal characteristics of the managed
    objects.
  • For example
  • A GIS system (Geographic Information System)
    stores, analyzes and processes geographic data
  • Files in a library must contain the details of
    borrowed and returned books.
  • The objects that are managed by a GIS are spatial
    objects, and the information about the borrowed
    books from the library files is a temporal object
    (it has to be known for each book when was
    borrowed and when was returned).

4
Spatial and Temporal Databases
  • As a first step, research in spatial and temporal
    areas was realized independently.
  • Spatial databases have focused on modeling and
    querying geometries associated with objects, but
    keeping in the database the current status of
    spatial objects. Thus, spatial databases are
    static databases.
  • Temporal databases, however, expanded the
    information in databases so that the previous
    states of objects were kept along with the
    current state of the modeled reality.
  • The need to join spatial and temporal data in a
    single application arose as a natural fact.

5
Space Time
  • Space-Time similarities
  • They are containers for objects (they include
    objects) an object exists in space at a
    specific location and has a specific lifespan).
  • Both can be defined as metric or topological
    spaces.
  • As a structure, they can have discrete, dense or
    continuous domains.
  • The notions of absolute and relative exist in
    both areas.
  • Space-Time differences
  • In space, the motion can occur in any direction
    (random), but in time is a one-way movement.
  • The time is dynamic, it is continuously flowing,
    but the space is static (as a container).
  • Usually, time is unlimited, and space is
    considered limited (in data modeling).
  • The relationships lt or ? can be easily
    defined on a temporal axis, but not in a 2D or 3D
    space.
  • The space is physically limited to three
    dimensions, but the time has no such limitations
    (you can define many temporal axes).

6
Spatio-temporal Databases
  • The ST objects are met very often in real life
    (also domains where these objects are required
    to be managed)
  • history (migrations),
  • biology (monitoring the spread of flora and fauna
    in time),
  • volcanoes (the evolution of volcanic eruptions),
  • multimedia applications (the management of
    objects that appear and disappear in a
    presentations frames),
  • military operations,
  • weather systems,
  • transportation systems,
  • wireless networks etc.

7
  • The space-time continuum is the scene where all
    the physical events take place, where the
    evolution of all physical objects is recorded.
  • The evolution of objects in space is given by the
    evolution line, surface, or volume (also known as
    world-line for points, world-sheet for lines, and
    world-volume for regions, respectively).

8
  • Figure 1. Helix
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