Geography Reference
In-Depth Information
Timeless maps are problematic because they portray the world in an 'eternal present'
and eliminate the concept of process. Langran (1992, p. 22) suggests that historically car-
tographers actively avoided dealing with time by mapping mostly static things with static
maps 'thereby shifting the burden of dealing with the temporal phenomena to the map user'.
Being constrained by static display technology (e.g. paper), the majority of Western maps
traditionally have emphasized space over time and, thus, are more often used to represent
states rather than processes. However, with the rise of geographic visualization (for experts)
and highly interactive web maps (for the public), representing time has become routine
in cartography. An active group of researchers have called for - and begun to develop -
empirically validated theories and practices upon which to create a robust understanding
of 'temporal cartography'.
4.2 Types of time
One of the primary reasons for making animated maps is to show spatial processes. As
Dorling and Openshaw (1992, p. 643) note:
It is self-evident that two-dimensional still images are a very good way (if not
the only way) of showing two-dimensional still information. However, when the
underlying patterns (and processes) start to change dynamically, these images
rapidly begin to fail to show the changes taking place.
Time and change, however, are broad concepts and, just as there are different types of
attribute data (e.g. categorical data, numerical data), there are different types of time. More
importantly, much as there are different graphic 'rules' for different kinds of spatial data
(e.g. sequential colour schemes match with numerical data series, qualitative colour schemes
with categorical data), there is reason to believe that different types of time require different
graphic approaches, although further work is needed in this area to elucidate what these
might be.
One of the first geographers to move beyond simple linear concepts of time was Isard
(1970), who characterized four types of time: universe time which is absolute and linear,
cyclic time such as diurnal patterns, ordinal time which records the relative ordering of
events, and time as distance in which the spatial dimension is used to represent time. Frank
(1994) identifies three basic kinds of time: linear, cyclic and branching. Linear time depends
upon the scale of measurement. Linear time measured at the ordinal scale is the sequence of
events, whereas linear time measured numerically is duration. Duration can be continuous
or discontinuous. Cyclic time expresses the idea of repetition or recurrence in the sequence
of events that can occur in either a regular or irregular manner. Branching time is used to
describe future possibilities. The further into the future one goes, the greater the number
of possible temporal paths. In complementary work, Haggett (1990) describes four types
of temporal change in geography: constants, trends, cycles and shifts. Constants (i.e. no
change) and trends (i.e. linear change) are long-term changes. Cycles describe recurring
patterns and shifts describe sudden changes (not necessarily recurring).
While there is no agreed upon list of the 'basic' kinds of geographic time, there are
commonalities within these frameworks: Isard, Frank and Haggert all include the concepts
of
linear time
and
cyclic time
in their respective typologies. These are perhaps the 'core' ideas
of time in geography and, as we discuss below, are reflected in widespread use of both cyclic
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