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Topic 1 Introduction to Geographic Information Systems

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Title: Topic 1 Introduction to Geographic Information Systems


1
Topic 1 Introduction to Geographic Information
Systems
  • A Information Technology and Geography
  • B The Purpose of GIS
  • C Organization of Information in a GIS

2
Conditions of Usage
  • For personal and classroom use only
  • Excludes any other forms of communication such as
    conference presentations, published reports and
    papers.
  • No modification and redistribution permitted
  • Cannot be published, in whole or in part, in any
    form (printed or electronic) and on any media
    without consent.
  • Citation
  • Dr. Jean-Paul Rodrigue, Dept. of Global Studies
    Geography, Hofstra University.

3
The Objectives of this Topic
  • Understand GIS as an information technology.
  • Understand the basic methods of information
    analysis in a GIS.

4
Information Technology and Geography
A
  • 1. What is Information?
  • 2. What is Geographical Information?
  • 3. What are Geographic Information Systems?

5
What is Information?
1
  • Information
  • 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.

Database A
Part No. Qty Description 103521 5 Wheel
spoke 105322 1 Ball bearing 106832 6 Wheel
rim 104338 2 Tire 103922 7 Handlebars
Database B
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
6
What is Information?
1
Database B
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
Geocoding
Elm
Smith
5th
Park
James
7
What is Information?
1
  • 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.

Information System
Encoding
Low order task Repetitive
Automatic Established Structure
Management
Analysis
High order task Unique
Reporting
Medium order task Common
8
What is Information?
1
  • 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
    are always imperfect (sub-optimal).

No Information
Pure Luck
Available Information
Imperfect Information
Sub-optimal Decisions
Optimal Decisions
Perfect Information
9
What is Geographical Information?
2
  • 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 Environmenta
l information Resource location
10
A Taxonomy of Information
1
  • Land Use
  • Name of places

GIS
  • Population
  • Temperature
  • Distance
  • Density

Spatial
Information
Qualitative
Quantitative
  • Name of people and organizations
  • Qualitatives
  • Stock market quotes
  • Quantitatives

Aspatial
11
What is Geographical Information?
2
  • 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).

Coordinate system
Scale
Time 2
Time 1
12
The Purpose of GIS
B
  • 1. What is a GIS?
  • 2. History of GIS
  • 3. General Purpose

13
What is a GIS?
1
  • 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.

14
What is a GIS?
1
  • Information Systems
  • Information system specializing in the input,
    storage, manipulation, analysis and reporting of
    geographical (spatially related) information.

Geographic Information System
Digitizing maps Encoding spatial data (census,
vegetation, topography, etc…)
Encoding
Geographic database in a spatial data format
Management
Analysis
Spatial analysis
Reporting
Thematic maps
15
Basic Structure of a GIS
1
Data Input
Geographic Database
Query
Transformation and Analysis
Output Display
16
What is a GIS?
1
Geographic
Information System
Records
Fields
17
History of GIS
2
  • 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.

18
History of GIS
2
  • 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.

19
General Purpose
3
  • 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.

20
General Purpose
3
  • 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.

21
General Purpose
3
  • 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.

22
General Purpose
3
  • 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.

23
General Purpose
3
  • 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.

People
GIS
Software
Data
Hardware
24
General Purpose
3
  • 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.

25
Organization of Information in a GIS
C
  • 1. Layers
  • 2. Features
  • 3. Attributes
  • 4. Relationships

26
Representation of Geographical Information in a
GIS
1
Thematic Map of the Continental United States
27
Maps are Composed of Layers
1
28
Features
2
  • 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.

29
Features
2
  • 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.

30
Features in ArcMap (Data View)
2
31
Attributes
3
  • 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.

Street name, Width, Direction, Lanes
Address, Lot , Type, Rooms, Owner, Value
32
Attributes
3
  • 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.

Features
Attributes
33
Attributes
3
34
Layout
4
  • 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.

35
Layout View in ArcMap
4
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