Geoscience Reference
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In this model, the focus is, therefore, above all spatial: changes are only
envisaged relatively to the geometry (shape), and the temporal dimension is
regarded as a dimension that allows identifying/controlling the definition of the
entities. Furthermore, the model is not adapted to an “object” approach.
From this pioneering attempt, a number of works have succeeded, some
constituting conceptual formalizations, others leading to operational developments.
We retrace the major steps because they constitute a set of interesting elements of
reflection. Each development indeed, allowed experimenting with a point of view
and going further into the conceptual and computer representation of a spatio-
temporal phenomenon. The developments have focused simultaneously on the
formalization of change and that of the temporal dimension of a phenomenon, and
this in a formal framework incorporating the duality of “object” and “field”
representation [PEU 88]. Thus in 1994, Peuquet proposed to extend the formal dual
framework associating the “location-based” and “object-based” to the “time-based”
temporal dimension. This framework places the triad framework at the forefront
enabling the identification of
what, where and when
[PEU 94]. Furthermore, this
framework formalizes the fact that our knowledge about phenomena is built through
the prism of three subcognitive systems that operate in different ways, but cannot
operate independently of each other. By allowing the positioning of a phenomenon
according to the spatial and temporal dimensions, this framework allows in
particular introducing the notion of event and representing it relatively to these
dimensions. Conceived that way, a system must be able to record all types of
changes. This framework has constituted a base for contemporary developments and
the following ones. Time is introduced in it with the same status as space. A
phenomenon can be conceptualized according to these 3Ds that find a simple
correspondence in the empirical domain and guide the structuring of the information
according to the three components: theme/time/space (Figure 1.8) [PEU 94,
YUA 99, MEN 00].
Other developments have committed themselves to express change, to define
primitives relatively to each of the three components. Therefore, change may refer to
the existence of the object (appearance/disappearance), to its spatial properties
(localization/form) or to its thematic properties (qualitative or quantitative). These
last two changes are often linked: the type of culture of a plot can change without
modifying its shape, but a change of shape usually causes a change in the quantity
produced, for example.
This is, for example, the case of the model proposed by Cheylan [CHE 95]: the
object is defined by its identity, its spatial extension and its thematic attributes. The
monitoring of its evolution needs, therefore, to integrate the change relative to each
of these three aspects: the movement for the spatial part (the movement is here
referred to in the sense of change in shape and/or localization), the genealogy for the
