A typical GIS can be understood by the help of various
definitions given below:-
information system (GIS) is a computer-based tool for mapping
that exist and events that happen on Earth .
Burrough in 1986
defined GIS as, "Set of tools for collecting, storing,
retrieving at will,
transforming and displaying spatial data
from the real world for a particular set of purposes"
3- Arnoff in 1989
defines GIS as, "a computer based system that provides four
sets of capabilities
to handle geo-referenced data :
i. data input .
ii. data management
(data storage and retrieval).
iii. manipulation and
The Geographic Information System has been an effective tool for
implementation and monitoring of municipal infrastructure. The
use of GIS has been in vogue primarily due to the advantage
1 .Planning of
2 .Make better decisions .
3 .Visual Analysis .
4 .Improve Organizational Integration .
Need of GIS?
Many professionals, such as foresters, urban planners, and
geologists, have recognized the importance of spatial dimensions
in organizing & analyzing information. Whether a discipline is
concerned with the very practical aspects of business, or is
concerned with purely academic research, geographic information
system can introduce a perspective, which can provide valuable
70% of the information has geographic location as it's
denominator making spatial analysis
an essential tool.
Ability to assimilate divergent sources of data both spatial
and non-spatial (attribute data).
Sharing of Information.
Factors Aiding the rise of GIS.
cost of Computer Hardware, and at the same time, exponential
growth of operational speed of computers.
functionality of software and their user-friendliness.
Visualizing impact of
GIS corroborating the Chinese proverb "a picture is worth a
and data describing it are part of our everyday lives & most
of our everyday decisions are influenced by some facet of
Philosophy of GIS
The proliferation of GIS is explained by its unique ability to
assimilate data from widely divergent sources, to analyze trends
over time, and to spatially evaluate impacts caused by
For an experienced analyst, GIS is an extension one's own
analytical thinking. The system has no in-built solutions for
any spatial problems; it depends upon the analyst.
The importance of different factors of GIS in decreasing order
is as under:
GIS involves complete understanding about patterns, space, and
processes or methodology needed to approach a problem. It is a
tool acting as a means to attain certain objective quickly and
efficiently. Its applicability is realized when the user fully
understands the overall spatial concept under which a particular
GIS is established and analyses his specific application in the
light of those established parameters.
Before the GIS implementation is considered the objectives, both
immediate and long term, have to be considered. Since the
effectiveness and efficiency (i.e. benefit against cost) of the
GIS will depend largely on
the quality of initial field data
captured, organizational design has to be decided upon to
maintain this data continuously. This initial data capture is
Planning Of Project
Advantage of GIS is often found in detailed planning of project
having a large spatial component, where analysis of the problem
is a pre requisite at the start of the project. Thematic maps
generation is possible on one or more than one base maps,
example: the generation of a land use map on the basis of a soil
composition, vegetation and topography. The unique combination
of certain features facilitates the creation of such thematic
maps. With the various modules within GIS it is possible to
calculate surface, length, width and distance.
The adage "better information leads to better decisions" is as
true for GIS as it is for other information systems. A GIS,
however, is not an automated decision making system but a tool
to query, analyze, and map data in support of the decision
making process. GIS technology has been used to assist in tasks
such as presenting information at planning inquiries, helping
resolve territorial disputes, and siting pylons in such a way as
to minimize visual intrusion.
Digital Terrain Modeling (DTM) is an important utility of GIS.
Using DTM/3D modeling, landscape can be better visualized,
leading to a better understanding of certain relations in the
landscape. Many relevant calculations, such as (potential) lakes
and water volumes, soil erosion volume (Example: landslides),
quantities of earth to be moved (channels, dams, roads,
embankments, land leveling) and hydrological modeling becomes
Not only in the previously mentioned fields but also in the
social sciences GIS can prove extremely useful. Besides the
process of formulating scenarios for an Environmental Impact
Assessment, GIS can be a valuable tool for sociologists to
analyze administrative data such as population distribution,
market localization and other related features.
Improving Organizational Integration
Many organizations that have implemented a GIS have found that
one of its main benefits is improved management of their own
organization and resources. Because GIS has the ability to link
data sets together by geography, it facilitates
interdepartmental information sharing and communication. By
creating a shared database one department can benefit from the
work of another--data can be collected once and used many times.
As communication increases among individuals and departments,
redundancy is reduced, productivity is enhanced, and overall
organizational efficiency is improved. Thus, in a utility
company the customer and infrastructure databases can be
integrated so that when there is planned maintenance, affected
people can be informed by computer-generated letters.
Components of GIS
GIS constitutes of five key components:
It consists of the computer system on which the GIS software
will run. The choice of hardware system range from 300MHz
Personal Computers to Super Computers having capability in Tera
FLOPS. The computer forms the backbone of the GIS hardware,
which gets it's input through the Scanner or a digitizer board.
Scanner converts a picture into a digital image for further
processing. The output of scanner can be stored in many formats
e.g. TIFF, BMP, JPG etc. A digitizer board is flat board used
for vacuolization of a given map objects. Printers and plotters
are the most common output devices for a GIS hardware setup.
GIS software provides the functions and tools needed to store,
analyze, and display geographic information. GIS software's in
use are MapInfo, ARC/Info, AutoCAD Map, etc. The software
available can be said to be application specific. When the low
cost GIS work is to be carried out desktop MapInfo is the
suitable option. It is easy to use and supports many GIS
feature. If the user intends to carry out extensive analysis on
GIS, ARC/Info is the preferred option. For the people using
AutoCAD and willing to step into GIS, AutoCAD Map is a good
Geographic data and related tabular data can be collected
in-house or purchased from a commercial data provider. The
digital map forms the basic data input for GIS. Tabular data
related to the map objects can also be attached to the digital
data. A GIS will integrate spatial data with other data
resources and can even use a DBMS, used by most organization to
maintain their data, to manage spatial data.
GIS users range from technical specialists who design and
maintain the system to those who use it to help them perform
their everyday work. The people who use GIS can be broadly
classified into two classes. The CAD/GIS operator, whose work is
to victories the map objects. The use of this victories data to
perform query, analysis or any other work is the responsibility
of a GIS engineer/user.
And above all a successful GIS operates according to a
well-designed plan and business rules, which are the models and
operating practices unique to each organization. There are
various techniques used for map creation and further usage for
any project. The map creation can either be automated raster to
vector creator or it can be manually victories using the
scanned images. The source of these digital maps can be either
map prepared by any survey agency or satellite imagery.