Geographic Information Systems as an Integrating Technology:
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1. Information Technologies in Geography
GIS is one of many information technologies that have transformed the
geographers conduct research and contribute to society. In the past two
decades, these information technologies have had tremendous effects on
research techniques specific to geography, as well as on the
ways in which scientists and scholars communicate and collaborate.
General Communication, Research, and Publication Technologies
- Cartography and Computer-Assisted Drafting: Computers
same advantages to cartographers that word-processing software offers
Automated techniques are now the rule rather than the exception in
- Photogrammetry and Remote Sensing: Aerial
technique for cartographic production and geographic analysis, is now
by the use of "remotely sensed" information gathered by satellites in
space. Information technologies have made both sorts of information far
more readily available and far easier to use.
- Spatial Statistics: Statistical analysis and modeling of
patterns and processes have long relied on computer technology.
in information technology have made these techniques more widely
and have allowed models to expand in complexity and scale to provide
accurate depictions of real-world processes.
- Geographic Information Systems (GIS): These systems
to collate and analyze information far more readily than is possible
traditional research techniques. As will be noted below, GIS can be
as an integrating technology insofar as it draws upon and extends
that geographers have long used to analyze natural and social systems.
- Communication and Collaboration: Electronic mail,
and computer bulletin boards make it far easier for colleagues to
ideas and share ideas, locally, nationally, and internationally.
techniques make it possible to hold interactive classes and workshops
at distant locations.
- Access to Library and Research Materials and Sources:
to both primary and secondary research resources is expanding rapidly.
From their offices, scholars can now get information held by libraries,
government agencies, and research institutions all over the world.
- Publication and Dissemination: Information technologies
substantially the cost of publishing and distributing information as
as reducing the time required to circulate the latest news and research
2. The Course of Technological
These advances in the application of information technologies in
began several decades ago and will continue to expand their effects
the foreseeable future. Scholars who have studied the spread of
innovations in society sometimes divide the process into four phases:
In geography, many innovations in the application of information
began in the late 1950s, 1960s and early 1970s. Methods of
mathematical and statistical modeling were developed and the first
sensing data became available. Researchers began also to envision the
of geographic information systems. The mid-1970s to early 1990s was a
of contagion. The first commercially available software for GIS became
available in the late 1970s and spurred many experiments, as did the
of the first microcomputers in the early 1980s. This was an exciting
in which the development of powerful software coupled with the
of inexpensive computers permitted many researchers to test new ideas
applications for the first time. In the early 1990s, or perhaps just a
bit earlier, many innovations entered the coordination phase even as
experimentation continued at a fast pace. The strengths and weaknesses
of many information technologies were by then apparent, and researchers
began to work together to cultivate the most promising applications on
a large scale. Arguably, the complete integration of information
in geography has yet to be achieved except perhaps in a few relatively
specialized research areas. Complete integration across the discipline
may, in fact, be many years away.
- Initiation: An innovation first becomes available.
- Contagion: Far-ranging experimentation follows to see
can be adapted to meet a wide variety of research and commercial needs.
Some, but not necessarily all of these experiments will work.
- Coordination: The most promising applications of the
gradually gain acceptance and are developed collaboratively. The
of experimentation helps to distribute the potentially high costs of
development and implementation.
- Integration: A innovation is accepted and integrated
3. GIS as an Integrating Technology
In the context of these innovations, geographic information systems
served an important role as an integrating technology. Rather than
completely new, GIS have evolved by linking a number of discrete
into a whole that is greater than the sum of its parts. GIS have
as very powerful technologies because they allow geographers to
their data and methods in ways that support traditional forms of
analysis, such as map overlay analysis as well as new types of analysis
and modeling that are beyond the capability of manual methods. With GIS
it is possible to map, model, query, and analyze large quantities of
all held together within a single database.
The importance of GIS as an integrating technology is also
in its pedigree. The development of GIS has relied on innovations made
in many different disciplines: Geography, Cartography, Photogrammetry,
Remote Sensing, Surveying, Geodesy, Civil Engineering, Statistics,
Science, Operations Research, Artificial Intelligence, Demography, and
many other branches of the social sciences, natural sciences, and
have all contributed. Indeed, some of the most interesting applications
of GIS technology discussed below draw upon this interdisciplinary
4. Geographic Information Systems: A
GIS is a special-purpose digital database in which a common spatial
system is the primary means of reference. Comprehensive GIS require a
Three observations should be made about this
First, GIS are related to other database applications, but
with an important difference. All information in a GIS is linked to a
reference. Other databases may contain locational information (such as
street addresses, or zip codes), but a GIS database uses geo-references
as the primary means of storing and accessing information.
- Data input, from maps, aerial photos, satellites, surveys, and
- Data storage, retrieval, and query
- Data transformation, analysis, and modeling, including spatial
- Data reporting, such as maps, reports, and plans
Second, GIS integrates technology. Whereas other technologies
be used only to analyze aerial photographs and satellite images, to
statistical models, or to draft maps, these capabilities are all
together within a comprehensive GIS.
Third, GIS, with its array of functions, should be viewed as a
rather than as merely software or hardware. GIS are for making
The way in which data is entered, stored, and analyzed within a GIS
mirror the way information will be used for a specific research or
task. To see GIS as merely a software or hardware system is to miss the
crucial role it can play in a comprehensive decision-making process.
5. Other Definitions
Many people offer definitions of GIS. In the range of definitions
below, different emphases are placed on various aspects of GIS. Some
the true power of GIS, its ability to integrate information and to help
in making decisions, but all include the essential features of spatial
references and data analysis.
- A definition quoted in William
Introduction to Urban Geographic Information Systems. (New York: Oxford
University Press, 1991), page 27, from some GIS/LIS '88 proceedings:
- ". . . The purpose of a traditional GIS is first and foremost
Therefore, capabilities may have limited data capture and cartographic
output. Capabilities of analyses typically support decision making for
specific projects and/or limited geographic areas. The map data-base
(accuracy, continuity, completeness, etc) are typically appropriate for
small-scale map output. Vector and raster data interfaces may be
However, topology is usually the sole underlying data structure for
- C. Dana Tomlin's definition, from
Information Systems and Cartographic Modeling (Englewood Cliffs, NJ:
"A geographic information system is a facility for preparing,
and interpreting facts that pertain to the surface of the earth. This
a broad definition . . . a considerably narrower definition, however,
more often employed. In common parlance, a geographic information
or GIS is a configuration of computer hardware and software
designed for the acquisition, maintenance, and use of cartographic
- From Jeffrey Star and John Estes, in
Information Systems: An Introduction (Englewood Cliffs, NJ:
1990), page 2-3:
"A geographic information system (GIS) is an information system that is
designed to work with data referenced by spatial or geographic
In other words, a GIS is both a database system with specific
for spatially-reference data, as well [as] a set of operations for
with data . . . In a sense, a GIS may be thought of as a higher-order
- And from Understanding GIS: The ARC/INFO
(Redlands, CA: Environmental System Research Institute, 1990), page 1.2:
A GIS is "an organized collection of computer hardware, software,
data, and personnel designed to efficiently capture, store, update,
analyze, and display all forms of geographically referenced
6. Related Terms: Acronyms,
One reason why it can be difficult to agree on a single definition for
GIS is that various kinds of GIS exist, each made for different
and for different types of decision making. A variety of names have
applied to different types of GIS to distinguish their functions and
One of the more common specialized systems, for instance, is usually
to as an AM/FM system. AM/FM is designed specifically for
management. It is defined further below.
In addition, some systems that are similar in both function
name to GIS, nevertheless are not really geographic information systems
as defined above. Broadly, these similar systems do not share GIS's
to perform complex analysis. CAD systems, for example, are sometimes
with GIS. Not long ago, a major distinction existed between GIS and
but the their differences are beginning to disappear. CAD systems, used
mainly for the precise drafting required by engineers and architects,
capable of producing maps though not designed for that purpose.
CAD originally lacked coordinate systems and did not provide for map
Nor were CAD systems linked to data bases, an essential feature of GIS.
These features have been added to recent CAD systems, but geographic
systems still offer a richer array of geographic functions.
The use of so many acronyms, synonyms, and terms with related
meaning can cause some confusion. Consider a few of the most widely
- AGIS (Automated Geographic Information System)
- AM/FM (Automated Mapping and Facilities
Automated mapping by itself allows storage and manipulation of map
AM/FM systems add the ability to link stores of information about the
mapped. However, AM/FM is not used for spatial analysis, and it lacks
topological data structures of GIS.
- CAD (Computer-Assisted Drafting): These
were designed for drafting and design. They handle spatial data as
rather than as information. While they can produce high-quality maps,
they are less able to perform complex spatial analyses.
- CAM (Computer-Assisted Mapping, or Manufacturing)
- Computerized GIS
- Environmental Information System
- GIS (Geographic Information System)
- Geographically Referenced Information System
- Geo-Information System
- Image-Based Information System
- LIS (Land Information System)
- Land Management System
- Land Record System
- Land Resources Information System
- Multipurpose Cadastre:
- Multipurpose Geographic Data System
- Multipurpose Land Record System
- Natural Resources Inventory System
- Natural Resources Management Information System
- Planning Information System
- Resource Information System
- Spatial Data Handling System
- Spatial Database
- Spatial Information System
7. The GIS View of the World
GIS provide powerful tools for addressing geographical and
issues. Consider the schematic diagram below. Imagine that the GIS
us to arrange information about a given region or city as a set of maps
with each map displaying information about one characteristic of the
In the case below, a set of maps that will be helpful for urban
planning have been gathered. Each of these separate thematic maps is
to as a layer, coverage, or level. And each layer has been
overlaid on the others so that every location is precisely matched to
corresponding locations on all the other maps. The bottom layer of this
diagram is the most important, for it represents the grid of a
reference system (such as latitude and longitude) to which all the maps
have been precisely registered.
Once these maps have been registered carefully within a common
reference system, information displayed on the different layers can be
compared and analyzed in combination. Transit routes can be compared to
the location of shopping malls, population density to centers of
In addition. single locations or areas can be separated from
locations, as in the diagram below, by simply cutting all the layers of
the desired location from the larger map. Whether for one location or
entire region, GIS offers a means of searching for spatial patterns and
Not all analyses will require using all of the map layers
In some cases, a researcher will use information selectively to
relationships between specific layers. Furthermore, information from
or more layers might be combined and then transformed into a new layer
for use in subsequent analyses. This process of combining and
information from different layers is sometimes called map "algebra"
as it involves adding and subtracting information. If, for example, we
wanted to consider the effects of widening a road, we could begin with
the road layer, widen a road to its new width to produce a new map, and
overlay this new map on layers representing land use.
8. The Appeal and Potential
The great appeal of GIS stems from their ability to integrate great
of information about the environment and to provide a powerful
of analytical tools to explore this data. The example above displayed
a few map layers pertaining to urban transportation planning. The
included would be very different if the application involved modeling
habitat of an endangered species or the environmental consequences of
from a hazardous materials site.
Imagine the potential of a system in which dozens or hundreds
of maps layers are arrayed to display information about transportation
networks, hydrography, population characteristics, economic activity,
jurisdictions, and other characteristics of the natural and social
Such a system would be valuable in a wide range of situations--for
planning, environmental resource management, hazards management,
planning, or transportation forecasting, and so on. The ability to
information in layers, and then combine it with other layers of
is the reason why GIS hold such great potential as research and
9. Application Areas
GIS are now used extensively in government, business, and research for
a wide range of applications including environmental resource analysis,
landuse planning, locational analysis, tax appraisal, utility and
planning, real estate analysis, marketing and demographic analysis,
studies, and archaeological analysis.
One of the first major areas of application was in
resources management, including management of
One of the largest areas of application has been in facilities
management. Uses for GIS in this area have included
- wildlife habitat,
- wild and scenic rivers,
- recreation resources,
- agricultural lands,
Local, state, and federal governments have found GIS
useful in land management. GIS has been commonly applied in
- locating underground pipes and cables,
- balancing loads in electrical networks,
- planning facility maintenance,
- tracking energy use.
More recent and innovative uses of GIS have used
based on street-networks. GIS has been found to be particularly
- zoning and subdivision planning,
- land acquisition,
- environmental impact policy,
- water quality management,
- maintenance of ownership.
- address matching,
- location analysis or site selection,
- development of evacuation plans.
10. Many Software Systems Support GIS
These days, dozens of software systems offer GIS decision-making
The range and number available sometimes make it difficult to discern
differences among systems and the strengths and limitations of each.
important point to remember is that there are as many different types
GIS software systems as there are decision-making processes. Particular
GIS software systems are often specialized to fit certain types of
making. That is, they are customized to meet needs specific to
forecasting, transportation planning, environmental resource analysis,
urban planning, and so on. These systems may respond well to individual
problems, but they are also limiting. Special- purpose GIS designed for
airport planning and maintenance, for instance, will not be well suited
to demographic modeling.
Other software systems are not so specialized. The Intergraph
MGE/MGA system or ArcGIS (produced by the Environmental Systems
Institute) have become well-known because they
can be used in a wide number of applications. These general purpose
also offer features that can be customized to meet various individual
Other systems such as MapInfo attempt
to provide functions that will be of value in one or more of the broad
application domains, for instance in demographic analysis or marketing
research. Yet quite apart from these more general systems, there are
of very specialized software systems that are best suited to one task,
one application, or even to just one part of a broader decision- making
process, for example for storing maintenance records of a highway
or for planning the expansion of an electric distribution network.
Chapter 1 in Bolstad, Paul. 2005. GIS Fundamentals: A First Text on
Geographic Information Systems, 2nd. ed. White Bear Lake,
MN: Eider Press.
Chapter 1 in Chang, Kang-tsung. 2006. Introduction to Geographic Information
Systems, 3rd. ed. Boston: McGraw Hill.
Chapter 1 in Clarke, Keith C. 2003. Getting Started with Geographic
Information Systems, 4th ed. Upper Saddle River, NJ:
DeMers, Michael N. 2005. Fundamentals
of Geographic Information Systems, 3rd ed. Wiley.
Chapter 1 in Lo, C.P. and Albert K.W. Yeung. 2002. Concepts and Techniques of Geographic
Information Systems. Upper Saddle River, NJ: Prentice Hall.
Chapter 1 in Longley, Paul A., Michael F. Goodchild, David J. Maguire,
and David W. Rhind. 2005. Geographic
Informaiton Systems and Science, 2nd ed. Hoboken, NJ:
Last revised 2009.1.11. KEF.