Geography Reference
In-Depth Information
2.3.4 Spatial context and neighbourhood
One of the great benefits of georeferencing is the access it provides to other information about
places. Insights are often to be gained by looking at information in geographic context, since
context can often suggest explanations or additional hypotheses. Context can be interpreted
in two distinct ways in the context of Google Earth, and indeed any geographic information
technology. Horizontal context concerns neighbouring features, and the degree to which
they may explain events or conditions. Vertical context concerns the role of features on
other layers, and the possibility that events or conditions at some location are attributable
to other events or conditions at the same location. Both vertical and horizontal context are
readily apparent in Google Earth. The mashup of sites associated with the novels of Jane
Austen (http://bbs.keyhole.com/ubb/showflat.php/Cat/0/Number/411188/an/0/page/0) is
an excellent example of using Google Earth to provide geographic context to a body of
literature and its author.
2.3.5 Scale
Scale has two distinct meanings in a geographic context: the extent of an area of interest, and
the degree of detail or resolution of its representation. A large-scale study might refer to one
covering a large area of the Earth, or to one that examines some area at coarse resolution. To
confuse things further, scale in a mapping context has often meant the ratio of the distance
between two points on the map to the distance between the same pair of points on the
Earth's surface, known as the representative fraction (RF). In this context a 'large' ratio or
scale indicates a map with a fine rather than coarse level of detail.
Google Earth handles scale through its zoom function, allowing the user to slide from
coarse to fine and back again. The resolution of the screen defines the fineness or coarse-
ness of the image, and limits the amount of data that must be sent over the Internet to
create it. Distance on the Earth can be determined using the measuring tool, and the con-
cept of representative fraction, which is meaningful only for paper maps, is effectively
abandoned.
The resolution of base imagery varies markedly over the Earth, from less than a metre
in some urban areas to tens of metres elsewhere (Figure 2.3). Resolution is a function of
the instrument used to acquire the imagery, which in Google Earth is created by stitching
together data from a large number of sources, including Earth-orbiting satellites and aircraft.
2.4 The social perspective
Google Earth presents social scientists both with a powerful tool for displaying the results of
research, and with a topic worthy of study in its own right. This section addresses some of
the issues that arise in that latter context. Like many other forms of geographic information
technology, Google Earth at first sight appears neutral in its impacts, and it is hard to imagine
its developers expressing much concern over the subtle ways in which it might influence
the world. At a somewhat deeper level, however, such technologies raise interesting and in
some cases disturbing questions.
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