Geography Reference
In-Depth Information
15.4.4 The Black Death display in the space-time cube
(stations at work)
This example deviates from the basic time-geography approach. It is an experiment to see if
the exploratory environment can also be used in epidemiological research. The Black Death
is used as a case study. This has recently been discussed in quite some detail by (Christakos
et al.
, 2005). In this case study the objects of study are not moving humans but the Black
Death epidemic that struck Europe in mediaeval times. Available data includes locations
[see map in Figure 15.5(a)] for which there is a start and an end date of the epidemic and the
number of deaths known or estimated. In the space-time cube terminology the locations
are considered stations with attributes. The cube in Figure 15.5(c) displays them with their
attribute values. This results in stations that vary in thickness depending on the number
of deaths, and they appear only between the start and end dates of the epidemic at that
particular location. The cloud of stations gives an impression of how the epidemic spread
through Europe. Since the epidemic started in southern Europe and moved northwards,
the locations in northern Europe are found in the upper half of the cube. If one looks
at the cube from above, one can create a station-animation by moving the base map along
the time axis.
The upper graph in Figure 15.5 contains all locations in alphabetical order with the
starting date of the Black Death as an attribute. It is possible to sort the graph based
on this starting date. The resulting sort order as seen in the lower graph can be used
to create a space-time path. This would result in a path through the cube, giving an
impression of the temporal spread of the epidemic [see Figure 15.5(f)]. Of course one
has to realize that this is not necessarily the real spread of the disease across Europe.
Similarly, one could swap the station's attributes in the graph to, for instance, the num-
ber of deaths, and generate a path starting with the lowest to the highest number of
deaths. Such a path might not have real meaning and would result in a chaotic path
going back and forth in time. However, let us not forget that new ideas come from un-
orthodox actions. Another such action would be to display the terrain model in the cube
to see if the terrain had some influence on the spread of the disease. Back in that time
the means of transport were much simpler and slower. A real interpretation of the view
would be the task of an epidemiologist, but orthodox views on their data can also be of
benefit.
15.4.5 Rotary Clubs in the Netherlands
(splitting space-time paths)
Figure 15.6 shows the location and development of the Rotary Clubs in the Netherlands.
The map shows their location (dots) and the spread (lines). In the cube the clubs are
represented by stations. Stations appear when the clubs started. The horizontal lines in the
cube link new clubs with their parents. The cube's base map can be moved along the time
axis. It is possible to animate the movement along the time axis and see the clubs appear
in both the cube and the map. The stations could be coloured according to specific club
attributes.
Search WWH ::
Custom Search