Geographic Information Systems
Definition: A Geographic Information System (GIS) is a collection of computer hardware, software and
geographic data used to analyse and display geographically referenced information.
Modern GIS maps are created using
Computer Aided Design (CAD) software to digitally render
geographical maps, onto which can be superimposed any spatially located variables (i.e.
rainfall, demographic data, etc.). GIS maps are used to create a visual representation of
raw data (attributes) to allow for more efficient analysis and
better decision making.
There are many GIS software applications available, ranging from open-source software
such as GRASS to proprietary applications created by such organisations as AutoDesk and
ESRI. There are also many specialist GIS applications developed for particular industries
(such as General Electric’s Smallworld, developed for use in GIS mapping of public utilities).
History of GIS
We have long used maps as a method of exploring the earth and locating natural resources.
In fact, the origins of GIS are rooted as far back as 35,000 years ago, when early man drew
cave paintings of the animals they hunted along with crude maps depicting migration trails.
While the cave paintings only vaguely resemble today’s advanced geographic information systems
they contain the same basic data as modern systems: geographic data linked with spatially
dependent attribute information.
The more sophisticated modern GIS can be tracked to John Snow’s 1854 map of the distribution
of incidences of cholera in 19th century London. While it is only a fairly basic 2-dimensional
rendering, Snow’s map is a useful tool to demonstrate the data analysis possibilities of GIS.
When viewed in isolation, a list of cholera cases suggests nothing as to the origin of the
outbreak. When that same data is translated into a GIS map the data takes on new meaning,
allowing the analyst to track down the outbreak to an infected water pump in the centre of a
cluster, giving the authorities the opportunity to curtail the outbreak and save lives.
Applications of GIS
Quite simply, GIS provides a method by which geographically dependent data can be displayed
in an easily understandable visual format to simplify the process of decision making. The
possible applications of such a tool would stretch to several volumes, but here are a few
examples of the possible uses:
* Earthquake Mapping
GIS is often used to map tectonic activity in earthquake prone regions for purposes of both
public safety and commercial interests.
Commercially, tectonic activity would be of great interest for the decision making process of
insurance companies in setting earthquake insurance premiums. Clearly, premiums will be much
higher in tectonically active areas such as the West Coast of the United States than in relatively
stable regions such as the Mid-West. To enable insurance brokers to determine premiums it is
necessary to utilise GIS software in mapping past tectonic activity in order to make a ‘best guess’
about future earthquake events.
Tectonic mapping through GIS is also used as a public safety measure by the United States
Geological Survey (USGS). These GIS maps are essential for creating and updating building
codes. They can also be extremely useful for the purposes of studying past earthquake events
in order to improve and perfect prediction techniques with a view to creating an early warning
system which would predict earthquakes and allow emergency response organisations such as FEMA
to react more quickly to natural disasters.
* Market Research
Rather less urgent - but no less important to industry - is the fact that GIS can be used to
make decisions regarding the provision of products and services. For instance, enterprises
can use GIS to analyse demographic data in an effort to locate the regions in which their
products can be expected to succeed (high-income regions for luxury items, for example). This
sort of analysis can be extremely useful in apportioning a limited advertising budget, allowing
the funds to be effectively channelled towards regions densely populated by the target demographic.
* Demographics, Health Research and Census Data
The range of data collected by governments about their citizens can be truly enormous. In their
raw form these data are largely useless to all but the most committed of researchers. When translated
into an easily understandable visual format by GIS software, however, census data can be of great
use in the shaping of public policy. Data regarding such subjects as health and education levels
can be used to better apportion government spending in these areas, leading (ideally) to more efficient
use of government funds, increased life expectancy, the creation of jobs and an upturn in economic
growth, along with a whole host of subsidiary social benefits. Additionally, GIS can aid health workers
in such fields as cancer research.
Free GIS software
There are several open source and other GSI software and GSI tools available.
There is this category
in gsiwiki. There's also
- The Free GIS Project
- Geomatica, scripts, tools,
extensions and more
- MapWindow (open source)
- Tatuk GIS viewer
- ArcExplorer GIS data
ArcReader & MapExplorer)
- MapMaker Gratis
- Brava Reader
- ERDAS Viewfinder
and other collections (1)
(4) of free