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GEOG 60 Introduction to Geographic Information Systems

Professor: Dr. Jean-Paul Rodrigue

Topic 1Introduction to Geographic Information

Systems

A Information Technology and Geography

B The Purpose of GIS

C Organization of Information in a GIS

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The Objectives of this Topic

Understand GIS as an information technology. Understand the basic methods of information analysis in a

GIS.

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Information Technology and Geography

1. What is Information? 2. What is Geographical Information?

3. What are Geographic Information Systems?

A

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Database B

What is Information?

Information Knowledge about something.

Recorded in some way.

Information age The computer has become the

main mean of storing andaccessing information.

Tremendous amounts of digital

information created: Spreadsheets.

Databases. Internet.

Most of the interesting jobs

involve information processing.

1

Part No. Qty Description

103521 5 Wheel spoke

105322 1 Ball bearing

106832 6 Wheel rim104338 2 Tire

103922 7 Handlebars

Date Address Type

1/22 123 James St. Robbery

1/26 22 Smith St. Noise

2/24 9 Elm Dr. #4A Assault

3/02 12 Fifth Ave. Vandalism

3/10 1067 Park Robbery

Database A

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What is Information?

Database B

Date Address Type

1/22 123 James St. Robbery

1/26 22 Smith St. Noise

2/24 9 Elm Dr. #4A Assault3/02 12 Fifth Ave. Vandalism

3/10 1067 Park Robbery

1

James

Smith

Elm

5th

Park

Geocoding

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1

Information System

EncodingLow order task

Repetitive

Automatic

Established

Structure

High order taskUnique

Medium order task

Common

What is Information?

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.Management

Reporting

Analysis

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What is Information?

Knowledge is power Having information offers a way

to control the parameters of our

environment. Making decisions (resource

allocation). With perfect information, one

should be able to make optimal

decisions.

Impossible to be perfectly

informed, so decisions arealways imperfect (sub-optimal).

1

AvailableInform

ation

PerfectInformation

OptimalDecisions

No InformationPure Luck

Imperfect

InformationSub-optimal

Decisions

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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 thisinformation are consequently

very useful.

Reveal information that was

previously hidden.

2

Destination

Customer addresses

Store / factory / warehouse location

Census information

Environmental information

Resource location

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Name of people and

organizations

Qualitatives

Stock market quotes

Quantitatives

Population

Temperature

Distance

Density

Land Use

Name of places

A Taxonomy of Information1

Information QuantitativeQualitative

Spatial

Aspatial

GIS

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What is Geographical Information?

Spatially related 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 Spatial dynamics (variations in

space). Temporal dynamics (variations in

time).

2

Coordinate system

Scale

Time 1 Time 2

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The Purpose of GIS

1. What is a GIS? 2. History of GIS

3. General Purpose

B

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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.

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1Geographic Information System

Encoding

What is a GIS?

Information Systems Information system specializing

in the input, storage,

manipulation, analysis and

reporting of geographical

(spatially related) information.

Management

Reporting

Analysis

Digitizing maps

Encoding spatial data

(census, vegetation,

topography, etc)

Geographic

database in a

spatial data format

Spatial analysis

Thematic maps

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Basic Structure of a GIS

Geographic

Database

Data Input

Transformation

and Analysis

Query

Output: Display

1

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What is a GIS?1

Fields

Records

Geographic Information System

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History of GIS

Prior to 1960 GISs 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

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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 ofstoring and accessing information.

3

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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.

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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.

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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.

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General Purpose

People 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

Hardware

People

Software DataGIS

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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.

3

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Representation of Geographical Information in a GIS

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Thematic Map of the Continental United States

1

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Maps are Composed of Layers

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Capitals

1

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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

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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

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Features in ArcMap (Data View)2

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Attributes

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 beits name, area, hours of

operation, and maintenance

schedule.

3Street name, Width, Direction, Lanes

Address, Lot #, Type, # Rooms, Owner, Value

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Attributes

Relationships Features and their attributes are

linked.

Types: One feature as one record in a

database. Many features to one record.

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

Features

Attributes

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Attributes3

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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.

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Layout View in ArcMap4