Geographic Information

System
Unit II
 GIS-Definition
• A geographic information system (GIS) captures, stores,
analyzes, manages, and presents data that refers to or is linked to
location.
• It describes any information system that integrates, stores, edits,
analyzes, shares, and displays geographic information. GIS
applications are tools that allow users to create interactive queries
(user created searches), analyze spatial information, edit data,
maps, and present the results of all these operations.
• It is a computer based information system used to digitally represent
and analyse the geographic features present on the Earth' surface
and the events (non-spatial attributes linked to the geography under
study) that taking place on it. The meaning to represent digitally is to
convert analog (smooth line) into a digital form. "Every object
present on the Earth can be geo-referenced", is the fundamental
key of associating any database to GIS.
• Definitions
– Is a computer-based information system that enables capture,
modelling, manipulation, retrieval, analysis and presentation of
geographically referenced data.
– Is 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.
– Is a computer-based tool for mapping and analyzing things that exist
and events that happen on earth.
– Is an integrated set of hardware and software tools used for the
manipulation and management of geographic data.
• You are already using GIS in some way or the other without even
realizing it. If you use an internet mapping program to find
directions, you are actually using a GIS.
 What is GIS?
• A Geographical Information System is a tool, which can
accept large volumes of spatial data derived from a variety
of sources, retrieve, manipulate, analyse and display them
according to user-defined specifications.
 History of Development
• Main idea of GIS: idea of portraying different layers of data on a
series of base maps, and relating things geographically.

• Maps are efficient data storage devices but —

– but inefficient analysis tools.
– Imperfect method accounting for scale differences, data sources.
– Geospatial data poorly maintained.
– Maps and statistics are out of date.
– Data and information are inaccurate.
– No data retrieval service.
– No data sharing.

• With the advent and improvement in computer technology

(hardware), robust in speed and memory, smaller and cheaper, and
its capacity to provide cartographic output, resulted in the
development of GIS.
• When we think of geographical information in the form of maps,
photos taken from aircraft, and images collected from satellites, so it
may be difficult at first to understand how such information can be
represented in digital form as strings of zeros and ones.
• If we can express the contents of a map or image in digital form, the
power of computer opens an enormous range of possibilities for
communication, analysis, modelling and accurate decision making.
• Since the mid-1970s, specialized computer systems have been
developed to process Geographical Information in various ways,
which include the following:
– Techniques to input Geographical Information, converting the
information to digital form.
– Techniques for storing such information in compact format on computer
disks, CDs and other digital storage media.
– Method for automated analysis of geographical data, to search for
pattern, combine different kinds of data, make measurements, find
optimum sites or routes, and a host of other tasks.
– Techniques for display of data in the form of maps, images and other
formats.
– Capabilities for output of results in the form of numbers and tables.
• Its benefits are
– geospatial data are better maintained in a standard format.
– revision and updating are easier.
– geospatial data and information are easier to search, analyze and
represent.
– more value added product.
– geospatial data can be shared and exchanged freely.
– productivity of the staff is improved and more efficient.
– time and money are saved.
– better decisions can be made .
• Development and use of GIS dates back to several years.
– Late1950s, Transportation planners begin digitizing flow & traffic data for
mapping purposes.
– Mid 1960s, Canada Developed a Geographic Information System for
land resources study with the idea of building a database structure of
the area of study and for overlay/area calculations.
– Environmental Systems Research Institute (ESRI) created in 1969. In
1980s, ESRI had created a standard RDMS-based structure - the
integrated cartographic (arc) & RDMS (info) system was to be called
Arc/Info.
– Intergraph Corporation.
• Contemporary development is driven by commercial sector.
• De-classification of military applications & data leading to
proliferation of GIS.
• University-based development limited.
• Commercial sector continues to consolidate. ESRI is the single most
prominent GIS provider.
• Government Agencies taking the lead on data standardization,
decreased redundancy and data sharing.
• By use of GIS, a simplified world can be brought into the computer.
EVOLUTION OF GIS
 GIS – Multidisciplinary Science
• GIS in an integrated multidisciplinary science consisting of the
following traditional disciplines.
– Geography
– Statistics
– Cartography
– Operations Research
– Remote Sensing
– Computer Science
– Photogrammetry
– MathematicsSurveying
– Civil Engineering
– Geodesy
– Urban Planning
• Several alternative names:
– Land Information System (LIS)
– AM/FM-Automated Mapping and Facilities Management
– Environmental Information System (EIS)
– Resources Information System
– Planning Information System
– Spatial Data Handling System
Areas of GIS Applications
MAJOR APPLICATION AREAS OF GIS
 GIS Architecture

• Include four functional subsystems

– Data input (From maps, aerial photos, satellite imagery and from other
sources)
• by Keyboard entry, Coordinate entry of surveyed data using keyboard,
Manual digitizing, Scanning, Input of existing digital files.
– Data storage and retrieval
• Involves use of DBMS for maintaining the data in a file format.
– Data manipulation and analysis (Data transformation, analysis and
modelling)
– Data output and display (Data reporting such as maps, reports and
plans).
Computer software Components of a GIS
 Changes in
the real world
Take action Data collection

Users
Data sources

Decision support
Data input

Analysis
Data management
Data retrieval and
analysis

GIS
Structure
 Components of GIS
• Include
– Hardware
• Computers - For storage and processing data.
• Devices to capture and feed data into the system.
• A hardware system is supported by several hardware
components.
– Central processing unit (CPU)
• To executes the programs and controls the operation of all
components.
Usually a personal computer (PC) or a work station is selected for
the required CPU or as a server computer.
– Memory
• Main memory :essential for the operation of the computer because
all data and program must be in main memory for fastest access.
More than 64 M bytes are at least necessary for PC based GIS.
• Auxiliary memory : is used for large permanent or semi-permanent
files with slower access. Harddisks, floppy disks, magnetic tapes, or
optical compact disks (CD-ROM) are used. At least more than 1 G
bytes is required for hard disk in GIS.
– Peripherals
• Input devices : key board, mouse, digitizers, image scanners, digital
cameras, digital photogrammetric workstations etc.
• Output devices : color displays, printers, color plotters, film
recorders etc.
 – Software
• Functions and tools needed to store, analyze and display
geographic information.

Modular GIS Environment

Geographic forecasting information system

Integrated GIS and imaging

processing S/W solution
• A software system is composed of programs including
operating system, compilers and application programs.
– Operating System (OS) : controls the operation of the programs
as well as all input and output.
For Pcs : MS-DOS (IBM PCs) and WINDOWS is the dominant
OS.
For Workstations : UNIX and VMS are the dominant OSs.
– Compilers : convert a program written in a computer language to
machine code so that CPU can execute binary operation.
Commonly used languages include C, Pascal and FORTRAN
and BASIC etc.
– Application Programs : Many vendors are providing GIS
software systems
– Data
• Important component of GIS.
• Two forms – Geographic or spatial data and attribute of the
spatial data.
– People
• Objective of GIS is to support its users with appropriate data
and decision support tools.
– Methods
• Operating practices adopted unique to each organization.
• Proper implementation of GIS from hardware, software,
personnels operating them and delivery of product.
 Geographic Information System

• Organized collection of
– Hardware
– Software Software
People
– Network
– Data Data
– People
– Network
Procedures

Procedures

Hardware
GIS as an Information Infrastructure
GIS for Decision Support
 Standard GIS packages
• 1.ESRI – Arc Info,Arc View
• 2.AutoDesk – Auto CAD Map
• 3.Baylore University – GRASS
• 4.Clark Labs – IDRISI
• 5.International Institute for Aerospace survey and Earth Sciences – ILWIS
• 6.Map Info Corporation - Map Info
• 7.Think Space Inc. – Geo Media
• 8.Bently Systems,Inc. – Microsation
• 9. PCI Geomatics - PA MAP
• 10. TYDAC Inc. – SPANS
• 11.Caliper Corporation - Trans CAD
• 12.Northwood Technologies Limited- Vertical Mapper
• 13.Arc View and Arc Info 8 a desktop GIS package
• 14.Arc Info workstation which is same as ARC/INFO version 7.x
• 15.Grass is unique among GIS Software Packages maintained in both US and
Germany.
• 16.Trans CAD is GIS package specially designed for use by Transportation
professionals
• 17.Microsoft and Oracle entered the GIS industry
• 18.Microsoft “MAP POINT “
• 19.Oracle spatial provides the features to store, access and manage spatial data in
Oracle 8i,a RDMS.
LIST
LISTOF GISSOFTWARES
OF GIS SOFTWARES PRODUCERS
PRODUCERS AND
AND THEIR
THEIRMAIN PRODUCTS
MAIN PRODUCTS

 Autodesk Inc.(http://www3.autodesk.com/): Autodesk Map

 Baylor university ,Texas (http://grass.baylor.edu/): GRASS

 Bently Systems, Inc.(http://www2.bently.com/): Microstation

 Caliper Corporation (http://www.caliper.com/): Transcad, Maptitude

 Clark Labs (http://www.clarklabs.org/) IDRISI

 Environmental Systems Research Institute (ESRI), Inc. (
http://www.esri.com/): ArcGIS, ArcView 3.x
 LIST OF
LIST OFGIS SOFTWARES
GIS SOFTWARES PRODUCERS
PRODUCERS AND
AND THEIR
THEIRMAIN
MAIN PRODUCTS
PRODUCTS

 Intergraph Corporation (http://www.intergraph.com/): MGE, GeoMedia

 International Institute for Aerospace Survey and earth sciences, The

Netherlands (http://www.itc.nl/ilwis/): ILWIS
 Keigan Systems (http://www.keigansyatems.com/): MFworks, Keigan
grid
 Land management Information Center at Minnesota planning (
http://www.imic.state.mn.us/EPPL7/): EPPL
LIST OF GIS SOFTWARES PRODUCERS AND
THEIR MAIN PRODUCTS

 Manifold.net (http://www.manifold.net/): Manifold System

 Mapinfo Corporation (http://www.mapinfo.com/): MapInfo
 PCI Geomatics (http://pcigeomatics.com/): Geomatica

 (http://www.google.com/).
 (http://www.googlemapsmania. blogspot.com/)