Geoscience Reference
In-Depth Information
propose the term “unfolded time” when the time is made explicit by dates (analogy
with the “support” space) and that of “folded time” (analogy with the “active”
space) when time is taken into account via indicators summarizing the duration and
the events. The first case refers to Galton's “histories”, where time “carries” the
information about the system's status, the second refers to the temporal summaries
in a “chronicle” perspective. According to the question, one or the other approach
will be adopted in the applications. If recalling the example of the municipalities'
populations, it is therefore possible to work directly on the table of populations at
each date and to build demographic trajectories or to build indicators summarizing
the characteristics of change. This may be the variation in population over the
period. In this case, a differential of quantity between two dates is considered. This
can also be about a date or a period corresponding to an event which has some
meaning for the question: the date of the maximum population, the period during
which the average annual rate of growth has exceeded 1% per year, for example.
The summary indicator is a measure of time and can be processed as a quantitative
or ordinal variable. This second type of formalism is very often used because it
allows formalizing temporalities
a priori
.
Recalling the example of the geographical information matrix, Berry proposes a
table of data where time is “unfolded” and the space is of the “support” kind. The
formalization of an “active space” and a “folded time” complements this approach.
3.1.3.
From entities' dynamics to that of organizations: what is it that changes and
relative to what frame of reference?
Data formalization depends of course on the question that is raised, and on the
hypotheses available. Being interested in spatial dynamics, it is important to identify
the
level
to which the question precisely refers. Two families of questions can be
distinguished:
- The questions about
change in spatial organization
: the observed spatial
entities then correspond to a means of observation and are simply representative of
the observation granularity that is adopted, either this entity has a meaning for the
study (municipality, archaeological settlement, shop, etc.) or not (pixel,
measurement points). The interest is focused on the description and identification of
changes at the level of the whole set of entities considered. It may be the evolution
of the spatial organization which is targeted: what is for example the evolution of the
poverty configuration in this region? What change in land use has been caused by
the demographical dynamics of this city? It could also be the hierarchical
organization that is in focus, since it is often associated with these spatial
recompositions: what hierarchization recorded the settlement system between the 1st
and the 2nd Century for example?
