Introduction to GIS-1

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Introduction to GIS

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An introduction to
G I S

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AIM: To introduce the basic principles of GIS
After this lecture you should be able to:
• Provide a definition, and brief description of
the historical development, of GIS
• Describe the main components required to
run a successful GIS
• Give examples of some GIS applications

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Introduction to GIS
• In this lecture you will be introduced to some of
the basic principles of Geographical Information
Systems (GIS). A definition will be established
and a brief description of the historical
developments will be provided.
• Finally some of the main components required to
run a successful GIS will be defined. This includes
the types of data that a good GIS should be able to
handle.

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What is GIS?
• A technology
– hardware & software tools
• An information handling strategy
• The objective: to improve overall decision
making

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What is a GIS ?
• Geographic … location
• Information … data, transform data to make
it meaningful
• Systems… integrated components

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What is GIS?
• Firstly and most importantly a GIS is an
information system.

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• A system is a group of connected entities
and activities which interact for a common
purpose.
• In GIS the common purpose is decision
making for managing any spatially
distributed activity.

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• An information system is a set of processes,
executed on raw data to produce information
which will be useful in decision making
• A chain of steps leads from observation and
collection of data through to analysis.
• An information system must have a full range of
tools to handle observation, measurement,
description, explanation, forecasting and decision
making

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• Finally it is important to remember that GIS
can also help to achieve the overall
objective of improving the decision making
process, whether in an organization, or
within a project.

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Definition of GIS
• GIS is computer software that links geographic information (where
things are) with descriptive information (what things are). Unlike a flat
paper map, where "what you see is what you get," a GIS can present
many layers of different information.
 A geographic information system (GIS) is a computer-based tool for
mapping and analyzing spatial data. GIS technology integrates
common database operations such as query and statistical analysis with
the unique visualization and geographic analysis benefits offered by
maps.

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Definition of GIS
• Geographic Information System (GIS) is defined as an
information system that is used to input, store, retrieve,
manipulate, analyze and output geographically referenced
data or geospatial data, in order to support decision making
for planning and management of land use, natural
resources, environment, transportation, urban facilities, and
other administrative records

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GIS: a formal definition
“A system for capturing, storing, checking,
integrating, manipulating, analysing and
displaying data which are spatially
referenced to the Earth. This is normally
considered to involve a spatially referenced
computer database and appropriate
applications software”
Chorley Report, 1987

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• The definition comes from the Chorley
Report “Handling Geographic Information”;
HMSO, 1987.
• Not everyone agrees with this definition.
There are those who believe GIS forms part
of more established disciplines but these
definitions tend to ignore the cross
disciplinary nature of spatial data.

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Why is a GIS needed?
- geospatial data are poorly maintained
- maps and statistics are out of date
- data and information are inaccurate
- there is no data retrieval service
- there is no data sharing

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Why is GIS unique?
• GIS handles SPATIAL information
– Information referenced by its location in space
• GIS makes connections between activities
based on spatial proximity

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What distinguishes GIS from other information
systems?
• GIS integrates spatial and other kinds of
information within one system: it offers a
consistent framework for analyzing space
• GIS makes connections between activities based
on spatial proximity.
• GIS provides the mechanisms for undertaking the
manipulation and display of geographic
knowledge.

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GIS concepts is not new
• The concepts used in GIS are not new to
Geographers.
• In the purest sense Geographers have made use of
such systems for many years, but these have been
manually operated - card indexes with paper map
overlays, atlases and similar systems.
• The following is one example:

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The location of cholera cases and the position
of the water pumps in Soho, London 1854
• In the London Cholera epidemic of 1854
Dr. John Snow was able to locate the source
of the outbreak by plotting the locations of
fatal cases.

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GIS concepts are not new!
• London cholera epidemic 1854
Cholera death
Water pump
Soho
+

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• John Snow found that there was a concentration of
some 500 cases within a few hundred yards of one
particular public water pump on Broad Street,
Soho.
• Snow was able to prove this: when the pump
handle was removed, no new cases were
diagnosed in that Street.
• He proved that the pump had been the source of
the those cases and that the cholera was carried in
the contaminated water.

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Spatial information handling 1854
Cholera death
Water pump
Soho
+

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GIS: historical background
This technology has developed from:
– Digital cartography and CAD
– Data Base Management Systems
1
2
3
ATTRIB
ID X,Y
1
2
3
ID
1
2
3
CAD System Data Base Management System

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GIS: historical background
• GIS has developed from two independent
areas: digital cartography and databases.
• These developments are closely related to
the enormous growth in power, and the
corresponding reduction in the cost of
computer technology, since the late 1960’s.

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Digital Cartography
• The desire to use computers to replace manual
cartographic processes, particularly for the more
tedious tasks, was a focus in the 1970’s.
• Developments in digital cartography often resulted
from developments in the larger Computer Aided
Design (CAD) field.
• At the same time the 1960’s quantitative
revolution in Geography encouraged the
development of computer programs that could
undertake map analysis operations that would be
difficult or too time-consuming to undertake by
hand.

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Database links
• The use of Data Base Management Systems
(DBMS) is very important to the current
concept of GIS which involves the
integrating of spatial and non-spatial data.
• The development of relational DBMS was
particularly significant with examples such
as Oracle being widely used today.

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COMPONENTS OF GIS
1. H A R D W A R E
2. S O F T W A R E
3. D A T A
4. P E O P L E
5. M E T H O D S

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GIS Components
Specific applications /
decision making objectives
?
G I S
Spatial
data
Computer hardware /
software tools

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GIS Components
• The key to establishing this type of technology
within an information framework for the purposes
of decision making is INTEGRATION: the
linking together of technology, data and a decision
making strategy.
• What GIS is all about today is the bringing
together of spatial analysis techniques and digital
spatial data combined with computer technology.

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• But for many, GIS is much more than a computer
database and a set of tools: it is also a philosophy
for information management. Often GIS can form
the core of the information management within an
organization.
• There are of course other definitions too. GIS is
sometimes referred to as the tool whilst the user
may be the Spatial Information Scientist! In recent
times the whole subject area has also been referred
to as Geographic Information Management (GIM)
or even Geomatics

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Each of these components will now be
examined in further details.
1. Data
2. Software & hardware tools
3. GIS data manipulation & analysis

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Types of data
Maps
Satellite Images
Spatial non-spatial
Postcodes/ZIP codes
Photographs
Videography
Financial statements
Films
Schematic diagrams
KT1 2EE
RH8 9AA
SW1P 3AD
£12,000 23.45 56789
£23,456 12.45 23456
£45,987 29.57 87634

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Types of data
• Within an information system many different types of data
may be used, each of which has different characteristics.
• The data may be spatial in a direct sense in that it describes
a single location, or indirectly, in that the location is
inferred.
• The data may also be represented in a graphic, or non-
graphic form.

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• Maps are the main source of data for GIS
and the traditions of cartography are
fundamentally important to the way GIS’s
operate. It is important to remember,
however, that maps are not the only source
of spatial data.
• ‘What makes data spatial?’

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What makes data spatial?
Placename
Grid co-ordinate
Postcode
Distance & bearing
Description
Latitude / Longitude

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What makes data spatial?
• Spatial data has particular characteristics. These
can be described in terms of: shape, place and
relationship to other spatial data (or geometry,
location, and topology. It is also necessary to
model real world data (such as a road or building)
in terms of a geographical representation.
• For example, a road could be represented as a line
and the building perhaps as a small box on a map.
These features (line, box) are in fact models of the
actual real world features. Sometimes these
models are described as objects or entities too.

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• Another important aspect of spatial data is that it
often contains attribute information. That implies
that a description of the feature (the road) is held
in some form. The description might be the name
or the type of road (A, B, Motorway). This
information might be held in a database record or
simply written or depicted on a map.
• Finally spatial data by its very nature implies that
relationships are also recorded. When we look at
map data, we automatically interpret the relative
locations of the spatial data. Computers require
more explicit descriptions

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• Spatial data thus refers to information that is
associated with a location or place. It may be
recorded on a map, held as records in a database
or even be represented as a photograph.
• Remember that Geography is, in fact, the study of
spatial information and that we are surrounded by
geography.
• Most information is either spatial or has a spatial
component.

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Software & hardware tools

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Manipulation and analysis
• What is at ….?
• Where is it ….?
• What has been changed since ….?
• What patterns/features are associated with ..?
• What if …?

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Manipulation and analysis
• What would happen if . . .
A chemical leaked into a river?
• Where does . . .
The Green Belt exist in relation to the City?
• Has . . .
Population changed over the last ten years?
• Is there a spatial pattern related to . . .
Car ownership in our area?

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Manipulation and Analysis
• To be of any value a GIS must perform a wide
range of data manipulation and analysis
functions.
• Thus all good GIS systems should be able to
answer the types of questions listed above.
• The only limitations would be the availability
of data and the functions of the specific
software package.

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• In addition how each GIS is used to carry out such
analysis will vary.
• In this course you will be using ArcView / ArcGIS
Desktop GIS. You will carry out many of these
type of questions in terms of their functionality.
• At the end, it will be your interpretation of how
the software functions which will determine the
type of analysis that can be achieved.

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• Project planning will be an important issue
to consider if you decide to carry out further
analysis.

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GIS comprises of:
• Data input
• Storage
• Management
• Analysis
• Output

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Data Input
• There is a need to collect spatial data and
then transform it into a digital form.
• This is often a major bottleneck for many
GIS applications as costs can be high.
• Data sources.

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Storage
• Data is stored generally in raster or vector formats.
Each has advantages and disadvantages.
• The format is very important in determining the
potential applications of a system.
• For example, ArcView 3.2 can display both raster
and vector data but it cannot analyze raster data.
(Image Analyst Extension)

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Management
• Management is extremely important to manage
large volumes of spatial data efficiently and
effectively if GIS is to be cost justified.
• This is partly a function of data structures,
hardware platforms and software choice. It also
involves managing the human interface too.
• Never underestimate the amount of time required
to learn a new software package

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Analysis
• To be of any real value a GIS must perform
a wide range of manipulation and analysis
functions.
• The power of GIS is in the integration of
various data types and the ability to ask
“what if?” types of questions.

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Output
• High quality output in various forms
remains important for most GIS users.
• Communicating the results of GIS analysis
is as essential as the effective use of the
technology.
• Output may be in the form of new digital
spatial datasets, maps, tables, reports . . . .

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The benefits of GIS include:
• Better information management
• Higher quality analysis
• Ability to carry out “what if?” scenarios
• Improve project efficiency

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Many of these achievements are dependent on:
• Data availability
• The ease of use of the GIS software
• The understanding of the problem to be solved
• The time available
• The amount of funding for the project in hand
• A project may take longer than you first anticipate.

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Areas of GIS Applications
• Facilities management
• Planning and Engineering
• Marketing and retailing
• Environmental and Natural Resources
• Land Information System
• Street Network
• Transport/vehicle routing
• Health
• Insurance
and many more . . .

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Facilities management
• Utilities such as electricity, gas, water and cable
communication companies all use GIS systems to
store, retrieve and analyse their plant and
materials.
• Areas such as customer responses, demand
forecasting, fault analysis, network assessment
analysis, site planning, strategic planning and
market analysis can be generated by the GIS.

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Marketing and retailing
• These applications tend towards targeting
customers and identifying potential markets for
customers.
• The extensive datasets generated from the use of
loyalty cards can also be used in conjunction with
GIS.
• Other applications may include: media planning,
territory allocation and prospect analysis.

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Environmental
• Forestry management, impact analysis,
resource management, coastal zone
mapping, geophysical & geotechnical
surveys.

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Transport / Vehicle Routing
• This is an example of ‘real-time’ GIS and is used
particularly by vehicle routing companies and the
emergency services who need to know where
there vehicles are located at any given time.
• Vehicle routing can also be assessed in terms of
least cost or efficiency.
• In addition GIS may also be used for; dispatch,
scheduling, franchise planning as well as route
planning.

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Health
• Disease mapping as well as epidemiology,
facility planning, provider & purchaser
planning, expenditure monitoring and
patient analysis can all be carried out using
GIS.

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Insurance
• Risk distribution analysis, catastrophe
planning, customer service analysis, hazard
& prediction analysis and underwriting

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GIS for Decision Support
• GIS can provide decision makers with useful
information by means of analysis and
assessment of spatial database.

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Discussion Questions:
1. Compare between the diversity of definitions of
GIS.
2. Define GIS from the perspectives of:
– Applications
– Functions
– System structure
3. Compare GIS to an airline reservation system as
both represent an information system.

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Internet Course Group Site
• Post message:
aast_gis_2007@yahoogroups.com
• Subscribe:
aast_gis_2007-subscribe@yahoogroups.com

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The End