GIS Overview

    What is GIS 

    A Geographic Information System (GIS) allows us to view, understand, question, interpret, and visualize data in many ways that reveal relationships, patterns, and trends in the form of maps, globes, reports, and charts.    

    A GIS is an information system designed to work with data referenced by spatial / geographical coordinates. In other words, GIS is both a database system with specific capabilities for spatially referenced data as well as a set of operations for working with the data. It may also be considered as a higher order map. GIS technology integrates common database operations such as query and statistical analysis with the unique visualization and geographic analysis benefits offered by maps. These abilities distinguish GIS from other information systems and make it valuable to a wide range of public and private enterprises for explaining events, predicting outcomes, and planning strategies. (ESRI) A Geographic Information System is a computer based system which is used to digitally reproduce and analyze the feature present on earth surface and the events that take place on it.  In the light of the fact that almost 70% of the data has geographical reference as it's denominator, it becomes imperative to underline the importance of a system which can represent the given data geographically.

    A typical GIS can be understood by the help of various definitions given below:- A Geographic Information System is a computer based system which is used to digitally reproduce and analyze the feature present on earth surface and the events that take place on it.  In the light of the fact that almost 70% of the data has geographical reference as it's denominator, it becomes imperative to underline the importance of a system which can represent the given data geographically.

    1-   A geographic information system (GIS) is a computer-based tool for mapping and  analyzing things that exist and events that happen on Earth .

    2-  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 analysis.

    vi. data output.

    GIS Advantage  

    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 mentioned below:

    1 .Planning of project

    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 insights as

    1. 70% of the information has geographic location as it's denominator making spatial analysis an essential tool.
    2. Ability to assimilate divergent sources of data both spatial and non-spatial (attribute data).
    3. Visualization Impact.
    4. Analytical Capability.
    5. Sharing of Information.

    Factors Aiding the rise of GIS.

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


    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 development. 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:

    • Spatial Analysis
    • Database
    • Software
    • Hardware

    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 most important.  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.  Making Decisions 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.  Visual Analysis 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 easier. 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:


    Hardware 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.  Software 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 option.  Data 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.  People 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.  Method 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. 


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