What
is GIS?
 GIS at Penn State
Find out about research, courses, departments, resources, and people
at Penn State who use GIS
Other GIS related sites
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What GIS is
Geographic Information Systems (GIS) refer to programs that are able to
assemble, analyze and display geographic data.
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Typically, a GIS is used to relate different types of geographic data.
Polygons (eg. counties), lines (eg. rivers or utility lines), and points
(eg. population centers) can be identified by certain attributes unique
to each type of data.
This information can then be geographically identified and related.
One can determine, for instance, which polygon, based on area,
contains which utility lines, based on cost or delivery rate, near
the greatest
population centers.
Words like "near", "beside", "close to" and "within" all have mathematical
expressions in GIS that allow statistics to be applied over space, and
related between different kinds of data. |
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GIS is often used to analyze different spatial elements of our enviornment.
It is used by many different types of researchers.
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Businessmen use GIS to determine where in a city would be the best location
for a store, depending on the income and spending habits of the nearby
residents, as well as the physical characteristics of available lots.
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Agronomists use GIS to determine where to grow crops, depending on where
soil and land characteristics best match what particular crops prefer.
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Architects use GIS to determine where the best place for a house would
be on a plot of land, depending on slope class, soil characteristics and
distances to utility lines.
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Ecologists use GIS to determine what parts of a wetland have changed the
most over time, and combine that with the physical characteristics of the
area to determine which areas are most vulnerable.
What GIS is Not
GIS is not digital mapping. There are much more flexible graphics packages
that are available for developing a good map, such as Freehand or Illustrator.
Although most GIS programs will allow you to do mapping, it is not their
primary purpose. The resulting maps are usually of only moderate quality
and can be output in a limited number of formats.
Many people are confused about when they might need a GIS, and when
they can use a database program with less complex geographic routines,
such as Excel. Consider, for instance, that you might be studying the counties
of Pennsylvania and you had a variety of statistics for each county. If
you simply wanted to compare the data for each county, then you could use
a spreadsheet program. Given that you had records within your database,
it would be sufficient to tell you:
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which county has the highest population
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which county produces the most apples
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which county uses the most water
A GIS is necessary when you want to introduce geographic relationships
between objects in your database. For instance, a GIS can help you determine"
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which county within 300 miles of Pittsburgh has the lowest population
density
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which county on the border of between Pennsylvania and New York
produced the most pears
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which county along the Susquehanna River uses the least water
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