Introduction to Geographic
Information Systems
Dr. Larry Teeter
What is a GIS?
One of a Set
Geospatial technologies are technologies for collecting and dealing with
geographic information. There are
three main types:
Global Positioning Systems
Remote Sensing
Geographic Information Systems
Defining GIS
• Different definitions of a GIS have evolved
in different areas and disciplines
• All GIS definitions recognize that spatial
data are unique because they are linked to
maps
• A GIS at least consists of a database, map
information, and a computer-based link
between them
Definition 1: Dueker’s Feature
Model
"A geographic information system is a special case
of information systems where the database
consists of observations on spatially distributed
features, activities or events, which are definable
in space as points, lines, or areas. A geographic
information system manipulates data about these
points, lines, and areas to retrieve data for ad hoc
queries and analyses" (Dueker, 1979, p 106).
Definition 2: A GIS is an
information system
"An information system that is designed to
work with data referenced by spatial or
geographic coordinates. In other words, a
GIS is both a database system with specific
capabilities for spatially-referenced data, as
well as a set of operations for working with
the data" (Star and Estes, 1990, p. 2).
Definition 3: Paul Bolstad’s
Definition
(author of class text)
“a computer-based system to aid in the
collection, maintenance, storage,
analysis, output, and distribution of
spatial data and information”
Definition 4: GIS is a
multi-billion dollar business.
“The growth of GIS has been a marketing
phenomenon of amazing breadth and depth
and will remain so for many years to come.
Clearly, GIS will integrate its way into our
everyday life to such an extent that it will
soon be impossible to imagine how we
functioned before”
We usually understand GIS to be computerfacilitated system
GIS is NOT only software/hardware
Also includes:
•Trained personnel
•Supporting Institution
•Protocols for use
Why Learn GIS?..... Because GIS is Everywhere
Why computerize manual methods?
•To bring together data from multiple sources (synthesis)
•Analytical power
•measure distance, density, area
•overlay and buffer
•adjacency and proximity
•vicinity (neighborhood)
•networks
•intervisibility
•Flexibility
•Output Quality
Why GIS?
• Resource
depletion/degradation
• Increased problem
complexity
• Demands by the body
politic
• Improved capabilities
• Increased competition
Why GIS?
• Expanded capabilities
- do the heretofore
impossible
• Improved efficiency reduce speed of
analysis 10-fold or
more
Why GIS?
Traffic Information
Monitoring and Mapping Sea Ice
in near Real Time
Why GIS?
Pavement quality
inventory and
monitoring
Why GIS?
Sustaining Lobster
Fisheries in Penobscot
Bay
Why is it important?
Fisheries stocks
dwindling, lobster an
economic mainstay
with sustainable
harvests
From Observations and Process
Knowledge to Prediction and Action
Where did GIS come from?
• GIS is built upon knowledge from
geography, cartography, computer science
and mathematics
• Geographic Information Science is a new
interdisciplinary field built out of the use
and theory of GIS
Basic Concepts of a GIS
- spatial data from different data sources are registered to
same scale to form data planes (layers)
- These data are used together (overlaid) to
produce a variety of derived information
- data layers resource manager might use:
land ownership
right of way
land use
surface water
elevation
transportation networks
utilities
vegetation cover
endangered species
soil type
jurisdictional boundaries
pest & disease
Questions a user might ask of a GIS:
-Where is object A (RCW cavity trees)?
-Where is A in relation to place B?
-How many occurrences of type A are within
distance X of B?
-What is the value of function Z (distance from
parking area) at position X?
-How large is B (campground area, perimeter)
A Brief History of GIS
• GIS’s origins lie in thematic cartography
• Many planners used the method of map
overlay using manual techniques
• Manual map overlay as a method was first
described comprehensively by Jacqueline
Tyrwhitt in a 1950 planning textbook
• McHarg used blacked out transparent
overlays for site selection in Design with
Nature
A Brief History of GIS (cont.)
• The 1960s saw many new forms of
geographic data and mapping software
• Computer cartography developed the first
basic GIS concepts during the late 1950s
and 1960s
• Linked software modules, rather than standalone programs, preceded GISs
A Brief History of GIS (cont.)
• Computerized GIS began in mid - 60's
- CGIS - 1964
- MLMIS - 1969
- FRIS - early 70's
- required mainframe computers
- mini computers made technology more
accessible (early 80's)
A Brief History of GIS (cont.)
• GIS was significantly altered by (1) the PC
and (2) the workstation
• During the 1980s, new GIS software could
better exploit more advanced hardware
• User Interface developments led to GIS's
vastly improved ease of use during the
1990s
• During the 1980s, new GIS software could
better exploit more advanced hardware
Features as Objects
FEATURES
• The standard feature model divides a mapped
landscape up into features, that can be points, lines,
or areas.
• Almost all human activity and natural phenomena
are spatially distributed, so can be studied using a
GIS.
• A GIS uses map features to manage data.
POINT
LINE
R i v e
BM 123
AREA
r
L a k e
Figure 1.2 The Feature Model: Examples of a point feature (elevation bench mark), a line feature (river) and an area feature (lake).