GEOG 60 – Introduction to Geographic Information Systems
Professor: Dr. Jean-Paul Rodrigue
Topic 1 – Introduction to Geographic Information
Systems
A – Information Technology and Geography
B – The Purpose of GIS
C – Organization of Information in a GIS
The Objectives of this Topic
■ Understand GIS as an information technology.
■ Understand the basic methods of information analysis in a
GIS.
A
Information Technology and Geography
■ 1. What is Information?
■ 2. What is Geographical Information?
■ 3. What are Geographic Information Systems?
1
What is Information?
■ Information
Database A
Part No.
103521
105322
106832
104338
103922
Qty
5
1
6
2
7
Description
Wheel spoke
Ball bearing
Wheel rim
Tire
Handlebars
Database B
Date
1/22
1/26
2/24
3/02
3/10
Address
123 James St.
22 Smith St.
9 Elm Dr. #4A
12 Fifth Ave.
1067 Park
Type
Robbery
Noise
Assault
Vandalism
Robbery
• Knowledge about something.
• Recorded in some way.
■ Information age
• The computer has become the
main mean of storing and
accessing information.
• Tremendous amounts of digital
information created:
• Spreadsheets.
• Databases.
• Internet.
• Most of the “interesting” jobs
involve information processing.
1
What is Information?
Database B
Date
1/22
1/26
2/24
3/02
3/10
Address
123 James St.
22 Smith St.
9 Elm Dr. #4A
12 Fifth Ave.
1067 Park
Type
Robbery
Noise
Assault
Vandalism
Robbery
Geocoding
Elm
Smith
5th
Park
James
1
What is Information?
Information System
Encoding
Low order task
Repetitive
Automatic
Management Established
Structure
Analysis
High order task
Unique
Reporting
Medium order task
Common
■ Information Systems
• Dominant tool.
• Set of computer programs that
are used to input (encode)
information and store it in a
structured manner.
• Can be retrieved, analyzed and,
finally, reported as a table,
graph, map or picture.
What is Information?
■ “Knowledge is power”
“Pure Luck”
Sub-optimal
Decisions
Optimal
Decisions
Available Information
1
No Information
• Having information offers a way
to control the parameters of our
environment.
• Making decisions (resource
allocation).
Imperfect
Information
Perfect
Information
• With perfect information, one
should be able to make optimal
decisions.
• Impossible to be perfectly
informed, so decisions are
always imperfect (sub-optimal).
2
What is Geographical Information?
■ Spatial information
• Between 70 and 80% of the
digital information is spatially
related.
• Can be placed on a map.
• Tools to deal with this
information are consequently
very useful.
• Reveal information that was
previously “hidden”.
Destination
Customer addresses
Store / factory / warehouse location
Census information
Environmental information
Resource location
1
A Taxonomy of Information
GIS
• Land Use
• Name of places
Spatial
• Population
• Temperature
• Distance
• Density
Qualitative
Information
Quantitative
• Name of people and
organizations
• Qualitatives
Aspatial
• Stock market quotes
• Quantitatives
2
What is Geographical Information?
■ Spatially related
Coordinate system
• Can be assigned coordinates or
any spatial reference.
• On the surface of the earth.
• Involves location and
organization.
■ Scale
• Can be from general to specific.
• Simple to complex.
• A satellite can generate one
terabyte (1012 bytes) of
information per day.
■ Dynamics
Scale
Time 1
Time 2
• Spatial dynamics (variations in
space).
• Temporal dynamics (variations in
time).
B
The Purpose of GIS
■ 1. What is a GIS?
■ 2. History of GIS
■ 3. General Purpose
1
What is a GIS?
■ Geographic Information System
• Form of Information System applied to geographical data.
• Produce information which will be useful in decision-making.
• Managing use of land, resources, transportation, retailing,
oceans or any spatially distributed entities.
• Connection between the elements of the system is geography,
e.g. location, proximity, spatial distribution.
■ System of hardware, software and procedures
• Support the capture, management, manipulation, analysis,
modeling and display of spatially-referenced data.
• Solving complex planning and management problems.
1
What is a GIS?
Geographic Information System
Encoding
Management
Digitizing maps
Encoding spatial data
(census, vegetation,
topography, etc…)
Geographic
database in a
spatial data format
Analysis
Spatial analysis
Reporting
Thematic maps
■ Information Systems
• Information system specializing
in the input, storage,
manipulation, analysis and
reporting of geographical
(spatially related) information.
1
Basic Structure of a GIS
Data Input
Query
Output: Display
Geographic
Database
Transformation
and Analysis
1
What is a GIS?
Geographic Information System
Records
Fields
2
History of GIS
■ Prior to 1960
• GIS’s origins lie in thematic cartography.
• Many planners used the method of map overlay using manual
techniques.
■ The 1960s and 1970s
• Many new forms of geographic data and mapping software.
• First GIS developed in Canada for land use inventory.
• Development of the first computer cartography packages for
mainframe computers.
• First remote sensing images.
• Mathematical Models.
2
History of GIS
■ The 1980s and 1990s
•
•
•
•
First commercial GIS Packages.
Diffusion of Microcomputers.
Integration with other software (mainly CAD and databases).
US Census Bureau efforts in the 1980s:
• Digitize spatial, economic and demographic attributes of the United
States.
• Creation of the TIGER format (Topologically Integrated Geographic
Encoding and Reference ).
■ The 2000s
•
•
•
•
Integrated Information technologies with geography.
Powerful applications on desktop computers.
Web/network based data sources.
Portable and inexpensive field GISs with GPS capabilities.
3
General Purpose
■ GIS is a database application
• All information in a GIS is linked to a spatial reference.
• Other databases may contain locational information (street
addresses, zip codes, etc.).
• GIS database uses geo-references as the primary means of
storing and accessing information.
3
General Purpose
■ GIS is a tool
• Must serve a purpose.
• Not an end in itself but a mean (process) to achieve this end.
• Should be viewed as a process rather than as software or
hardware.
• For decision-thinking (scenarios) and decision-making
(strategies).
• 75% of the time used to be spent at building the spatial
database:
• Acquiring data for a new GIS has become much simpler.
3
General Purpose
■ Advantage
• Ability to integrate vast quantities of spatial information.
• Provide a powerful repertoire of analytical tools to explore this
data.
• Ability to separate information in layers:
• Combine it with other layers of information.
• Good employment opportunities (information society).
■ Disadvantage
• Long process of encoding and verifying the integrity of
information.
• Compatibility between different GIS (less an issue).
• Technology changes rapidly.
• Information overload.
3
General Purpose
■ GIS as an Integrating Technology
• Evolved by linking a number of discrete technologies:
• A whole that is greater than the sum of its parts.
• Integrate geographical data and methods:
• Support traditional forms of geographical analysis.
• Map overlay analysis.
• Thematic mapping.
• New types of analysis and modeling:
• Beyond the capability of manual methods.
• Possible to map, model, query, and analyze large quantities of data all
held together within a single database.
• Integrates people, data, hardware and software.
3
General Purpose
■ People
People
Software
GIS
Hardware
Data
• Map user: end consumer.
• Cartographer: producer of the end
product of a GIS.
• Analyst: applies methods to solve
geographical problems.
• Database administrator: build,
update and administer databases.
■ Data
• Remote sensing images or aerial
photographs.
• Topographic maps.
• Land records. Etc.
3
General Purpose
■ The GIS Job Market
• About 500,000 GIS users in the United States (another 500,000
for the rest of the world).
• 10% (50,000) are using GIS full-time.
• 15% growth each year.
• 75,000 people a year receive GIS training.
• Shortfall in training and advanced degrees.
• High demands to integrate GIS in all levels of the educational
system.
C
Organization of Information in a GIS
■
■
■
■
1. Layers
2. Features
3. Attributes
4. Relationships
1
Representation of Geographical Information in a GIS
Thematic Map of the Continental United States
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1
Maps are Composed of Layers
States
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Lakes
Roads
Capitals
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2
Features
■ Layers contain features or surfaces
■ Features
•
•
•
•
Real world objects.
Natural or man-made.
Represented on a map as a single entity.
Each map feature has a location, shape, and symbol that
represents one or more of its characteristics.
■ Surfaces
• Some elements do not have a distinct shape.
• E.g. : elevation, slope, temperature, rainfall.
• Raster is the most common surface; composed of a grid.
2
Features
■ Points
• Points represent objects that have discrete locations and are too
small to be depicted as areas.
• Schools, traffic lights, crime locations, and park benches are
examples of point features.
■ Lines
• Lines represent objects that have length but are too narrow to be
depicted as areas.
• Freeways, streets, pipelines, and waterways are examples of
line features.
■ Polygons
• Polygons represent objects too large to be depicted as points or
lines.
• Parks, census tracts, postal codes, and trade areas are
examples of polygon (or area) features.
2
Features in ArcMap (Data View)
3
Attributes
Street name, Width, Direction, Lanes
Address, Lot #, Type, # Rooms, Owner, Value
■ Attributes
• Features are stored in a
database along with information
describing them.
• The descriptive information
stored with a feature.
• Attributes of a street might
include its name, street type,
length, street code, number of
lanes, and pavement type.
• The attributes of a park may be
its name, area, hours of
operation, and maintenance
schedule.
3
Attributes
■ Relationships
Features
• Features and their attributes are
linked.
• Types:
• One feature as one record in a
database.
• Many features to one record.
Attributes
• Access the attributes for any
feature or locate any feature
from its attributes.
• Attributes are displayed in a
spreadsheet-like ArcView
document called a Table.
3
Attributes
4
Layout
■ Layout
• A GIS links sets of features and their attributes and manages
them together in units called layout.
• Consists of a collection of geographic features.
• Attributes for those features.
■ Thematic map
• A map (set of features) which visually represents a set of data
(attributes) is called a thematic map.
4
Layout View in ArcMap