Geographic Information System

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  • Topic: Geographic information system, Remote sensing, Cartography
  • Pages : 21 (4947 words )
  • Download(s) : 42
  • Published : February 14, 2009
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Geographic Information System (GIS) is a computer based information system used to digitally represent and analyze the geographic features present on the Earth's 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. Here, term 'database' is a collection of information about things and their relationship to each other, and 'geo-referencing' refers to the location of a layer or coverage in space defined by the co-ordinate referencing system. The term geo-referencing refers to defining the location, and other required features of any object, place, structure etc. in space defined by the co-ordinate referencing system.

The works on the GIS started in the late 1950’s but the credit of developing the first GIS software ultimately went to ESRI, Canada. The ESRI labs delivered the first GIS software in 1970’s. Much of the credit of the development of the GIS software could be given to “Mr. Roger Tomilson”.

GIS has revolutionized the way in which the planners, engineers, professional, etc. conduct the database management and the analysis. With the variety of data required by them to solve a definite problem available to them and having the required tools to manage that data, the GIS professionals are in a better stead to solve the real world problems.


Some of the proposed definitions of a typical GIS are as the following :

• A geographic information system (GIS) is a computer-based tool for mapping and analyzing things that exist and events that happen on Earth Burrough in 1986 defined GIS as, "Set of tools for collecting, storing, retrieving at will, transforming andì¥Á5@estions are posed to determine what happens, for example, if a new road is added to a network or if a toxic substance seeps into the local ground water supply. Answering this type of question requires both geographic and other information (as well as specific models). GIS permits spatial operation.

Aspatial Questions
"What's the average number of cows in each location?" is an aspatial question - the answer to it does not require the stored value of latitude and longitude; nor does it describe any relation between the places.

Spatial Questions
“How many people work with GIS in the major centres of Delhi" OR “Which centres lie within 10 Kms. of each other? ", OR “What is the shortest route passing through all these centres". These are spatial questions that can only be answered using latitude and longitude data and other information such as the radius of earth. Geographic Information Systems can answer such questions.

Factors Aiding The Rise Of GIS.
• Revolution in Information Technology.
• Computer Technology.
• Remote Sensing.
• Global Positioning System.
• Communication Technology.
• Rapidly declining cost of Computer Hardware, and at the same time, exponential growth of operational speed of computers. • Enhanced functionality of software and their user-friendliness. • Visualizing impact of GIS corroborating the Chinese proverb "a picture is worth a thousand words." • Geographical feature and data describing it are part of our everyday lives & most of our everyday decisions are influenced by some facet of Geography.

Components of GIS

GIS constitutes of five key components:
• Hardware
• Software
• Data
• People
• Method

The computer forms the backbone of the GIS hardware, which gets its 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...
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