Geography Reference
In-Depth Information
Geographical Information Systems (GIS)
GIS science is a major modern skill of the discipline of geography.
It has developed with increasing diversity into various forms
of sophisticated mapping combined with quantitative spatial
analysis. GIS data comprise digital representations of phenomena
found on the Earth's surface. These may be landforms, fi eld
boundaries, vegetation types, buildings, or a host of other features
that can be referenced to geographical coordinates. Once this
data has been collected, GIS software, such as MAPINFO,
allows a range of analyses and interpretations. GIS science
has a well-defi ned and developing set of scientifi c principles,
practices, and theories, and the methodology has proved to have
very considerable application. Global sales of GIS facilities and
services exceed $7 billion and fi nd markets throughout public
services such as local government and the police and in many
private sector areas such as fi nancial services and retailing. GIS
applications are problem centred and address long-standing
research questions in geography such as urban growth and
land-use change as well as newer challenges such as crime
profi ling, where many police forces routinely add a location code
to criminal events such as burglaries or homicides as a fi rst step
towards forms of GIS analysis. The example shown in Figure 24 is
from human geography and demonstrates the way in which GIS
can present data in different ways. This map of the countries of
the world shows the varying distribution of wealth, based upon
the Gross National Product (GDP). The territorial extent of each
nation state is distorted to refl ect its relative prosperity. Countries
such as the United States and most European states have a greatly
exaggerated size whereas countries in Africa and Latin America
are minimized.
GIS is one half of a duality of which Earth Observation (EO), an
alternative term for satellite remote sensing, is the other partner.
EO comprises a set of instruments or sensors, their carriers,
aircraft or satellites, and the data processing techniques that
