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Week 1, Lecture 2
March 28, 2014
Department of RS and GISc
Institute of Space Technology, Karachi
INTRODUCTION TO
GEOGRAPHICAL INFORMATION
SCIENCE
RSG620
Introduction to GIS

What is GIS?
G?
I?
S?
Geographical
Information
System
Science
Studies
What is Geography?
Definition:
Geography is the study of the world's environment
and man's interaction within the environment.”
Geography has two parts:
1. PHYSICAL:
The study of the earth's natural features, such as mountains,
rivers, soil, vegetation, and weather
2. HUMAN: (Cultural)
The study of human cultures and man made features.
“All kinds of resources are used to study geography, but the
most common are MAPS.”
S in GIS?

S as in System


S as in Science


Technology (for acquiring and managing GIS data)
Concept behind the technology. Theoretical foundation on
which GISystems are based
S as in Studies

Societal context (social, legal, issue of privacy and
confidentiality and ethical issues related to GIS application)
Why Geography is important?

Why are we more interested in spatial data today
than 100 years ago?
Reference: Bolastad, 2008
How an object on Earth can be
defined?
Location Information: Where is
it?
O
O
X South, Y West
Attribute Information: What is
it?
Type
…….
Species
…….
Heights
…….
Use
…….
GIS can tell us Where and What
Why GIS is Important?

What is Where? :

Query information to find location
Or

Where is what?



Obtain information from a location
Impact of spatial information on our lives?
Applied geography, in the form of maps and spatial
information, has served discovery, planning,
cooperation, and conflict for at least the past 3,000
years (Bolstad)
GIS is about Geospatial Information

Geospatial Information: Information about places on
earth

Not only Where and What but time is also important
What is Where, When?
Simpler Definitions

A GIS helps us gather and use spatial data (Bolstad)

A computer system which can hold and use data
describing places on the earth's surface.
A GIS is not simply a computer system
for
making
pretty
maps.
More
importantly a GIS...
• ... is an analysis tool
• ... links spatial data with geographic
information about a particular feature on a
map
• ... can use the stored attributes to compute
new information about map features

A GIS is a computer-based system to aid in the
collection, maintenance, storage, analysis,
output, and distribution of spatial data and
information.

A powerful set of tools for collecting, storing, retrieving,
transforming and displaying spatial data from the real
world. (Burrough, 1986)

Any manual or computer based set of procedures used to
store
and
manipulate
(Aronoff 1989)
geographically
referenced
data.
•
A decision support system involving the integration of
spatially
referenced
data
in
a
problem
solving
environment. (Cowen 1988)
•
Systems that know how to deal with stuff in space.
(Herrington 1998)
DATABASES
• A Database comprises
of tables having fields
with specific data
structure.
• The tables are linked
with each other through
various common fields.
MAPS
• Map can be defined as “A Facility
for displaying interpretation of
geographic information on a flat
surface.”
• Location information describes the
position of a particular geographic
feature on earth's surface & provides
the basis for representing spatial
relationships between these
features.
Bad
Searching
Very good
Searching
What? if link
together
Bad
Visual Interpretation
Very Good
Visual Interpretation
Capture
Collecting data using different data structures and
technologies – GPS, RS, Digitizing, etc.
Store
Data stored in the form of databases, spatial files,
drawings, images, etc.
Query
A GIS must provide utilities for finding specific
features based on their location or attribute values
Analyze
A GIS must have the ability to answer questions
regarding the interaction of spatial relationships
between multiple datasets
Display
There must be tools for visualizing the spatial
information in the form of maps
Output
Results of display should be able to be output in a
variety of formats
Data Capturing
Storing Data
 Tables
Spatial Query
Query: Select Florida county Taylor on map
Spatial Analysis
Remember!!

Queries manipulate the database

Analysis transforms data into information
Display
Output
Output
Soft Copy
Hard Copy
-
Electronic map (visual
digital map + multimedia)
-
Digital Atlas
-
Digital Layouts
-
Web Based Maps
(Interactive Web Mapping)
-
Maps (Topographic,
Statistical, 3D, Contour etc)
-
Atlases
-
Reports (Write-ups etc)
-
Charts, Graphs
GIS Key Components
1.
2.
3.
4.
5.
GIS hardware
GIS software
GIS data (maps, images, database, etc.)
People
Methods
Picture reference: http://www.mapsofindia.com/images/gis-components.jpg
Hardware
Hardware is the computer system on which software operates
Hardware
Reference: Bolstad
Software




GIS software combines spatial mapping and
analysis with database management
GIS software provides the functions and tools to
store, analyze, and display and disseminate
spatial data and information
Many public domain and commercially available
software packages in the market
ESRI (Environmental Systems Research
Institute) line of products a good example
(including ArcGIS)
Software
Key components to GIS software:
1. An easy-to-use graphical user interface (GUI)
2. Tools for entering and manipulating geographic
information
3. Tools that support geographic query, analysis and
visualization
4. A database management system (DBMS)
Functions Commonly Provided by GIS Software
Reference: Bolstad, 2008
GIS Data
Map + Database

Digital maps (virtual representation of world)

Map = Spatial representation of features
Database = Feature attributes

Data Sources
 Available through various sources like profit and nonprofit organizations, academic institutions,
government agencies
GIS Data
Flood Zones
Wetlands
Landcover
Electric Lines
Gas Pipe Lines
Soils
Land Ownership
Transportation
Surface Waters
Boundaries
Geodetic Control
Elevation
Satellite Imagery
GIS Combines Data from Many Sources
Data Format
GIS Data
People
• GIS personnel may include
– GIS technologist to design and maintain the
system
• General programmers
• GIS developers
– GIS Users
• GIS Managers
• Data providers
• GIS specialist/analyst
• General users and Public users
GIS Components
Methods



Analysis to be performed on data
To answer the question needs to be resolved
How to
›
›
›
›
›
›
›
Retrieve
Input into the system
Stored
Managed
Transformed
Analyzed
Presented as output
Other GIS Components


Supporting institution
Protocol for use
Some Advantages of GIS





Automation of procedures involving geographic data
(map making, calculation of area, slope, etc., and
planning and management activities)
Integration of data from different independent
domains
Visual Interpretation of spatial data depending on
various criteria
Perform Spatial Queries and complex Spatial
Modeling (what if scenarios)
More
•
Geo-spatial data are better maintained in a standard format
•
Revision and updating are easier
•
Easier to search, analyze and represent
•
More value added as well as thematic product
•
Geo-spatial data can be shared and exchanged easily
•
Working productivity is improved and more efficient
•
Time and money are saved
•
Better decisions in short span of time
THANK YOU