GIS

What is GIS?

Geographic Information System (GIS) is defined as 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.

GIS application potential

The strength of GIS depends upon how good is the geospatial database. It can be used for natural resource application (i.e. forestry, agriculture and water resources etc.) in combination with remote sensing and earth observation. In addition it is used for infrastructure development (i.e. highways, railways etc.); utility services like water supply distribution network, telephone network management, gas supply distribution etc.; business application such as real estate, establishment of new retailer shops; heath services; investigation services like crime incidences and their distribution etc. In addition GIS can be used for research and scientific investigations, particularly for water budgeting, atmospheric modelling, climatic studies and global warming.

Component of GIS :                                 

1.Hardware

Hardware is the computer on which a GIS operates. Today, GIS software runs o a wide range of hardware types, from centralized computer servers to desktop computers used in stand-alone or networked configurations

2.Software

GIS software provides the functions and tools needed to store, analyze, and display geographic information. Key software components are:

• •  Tools for the input and manipulation of geographic information

  •  A database management system

  •  Tools that support geographic query, analysis and visualization

  •  A graphical user interface (GUI) for easy access to tools

3.Data

Possibly the most important component of a GIS is the data. Geographic data and related tabular data can be collected in-house or purchased from a commercial data provider. A GIS will integrate spatial data with other data resources and can even use a DBMS, used by most organizations to organize and maintain their data, to manage spatial data.                            

 4.People

GIS technology is of limited value without the people who manage the system and develop plans for applying it to real-world problems. GIS users range from technical specialists who design and maintain the system to those who use it to help them perform

5.Methods

A successful GIS operates according to a well-designed plan and business rules, which are the models and operating practices unique to each organization.

GIS Software: Commercial versus Open/free

GIS software is one of the bottlenecks in GIS industry as the major junk money (~50 % or so) is invested towards its procurement and maintenance annually. Because of it many users have apprehensions to change from conventional methods to GIS. In the recent past there is a paradigm shift in usage of GIS software. There are many new and open/free software are launched into the market. The free software where it is freely available and mostly through WWW but the user do not have access to program coding, so not possible to modify or update it. In case of open source, it is free as well as available with full access to program coding so user can modify/update it according to his requirements.

Advantages of GIS

– Exploring both geographical and thematic components of data in a holistic way

– Stresses geographical aspects of a research question

– Large volumes of data

– Integration of data from widely disparate sources

– Allows a wide variety of forms of visualisation

Disadvantages of GIS

– Data are expensive

– Learning curve on GIS software can be long

– Shows spatial relationships but does not provide absolute solutions

– Origins in the Earth sciences and computer science. Solutions may not be appropriate for humanities research

Need for GIS

Any organization, government or private is in some way or another strongly linked to the geography in which it operates. A GIS that has been designed in a proper manner has the capability of providing quick and easy access to large volumes of data of these geographical features. The user can access & select information by area or by theme to merge one data set with another, to analyze spatial characteristics of data, to search for particular features, to update quickly and cheaply and asses alternatives.

In simpler terms, GIS allows the user to understand geographic information in an easy manner without having to go through large volumes of confusing data that is in tabular form. Visualizing the geography of a particular location is no doubt easier that trying to analyze raw data. The potential and substantial benefits of using GIS makes it a very important tool making the work of any organization easier and more productive. Some of the potential benefits of GIS are:

• Opportunity to reduce sets of manual maps held and associated storage costs.  Faster and more extensive access to geographic information.

• Improved analysis e.g. areas, distances, patterns, etc.

• Better communication of information to public officers, members.

• Improved quality of services.

• Better targeting and coordination of services.

• Improved productivity in providing public information. Improved efficiency in updating maps.

• The ability to track and monitor growth and development over time.  Improved ability to aggregate data for specific sub areas.

• Thus GIS's have become indispensable tools for governance, commerce, and environmental and social science.Functions of GIS

The Functions of GIS describe the steps that have to be taken to implement a GIS. These steps have to be followed in order to obtain a systematic and efficient system. The steps involved are:

I) DATA CAPTURE:

Data used in GIS often come from many sources. Data sources are mainly obtained from Manual Digitization and Scanning of aerial photographs, paper maps, and existing digital data sets. Remote-sensing satellite imagery and GPS are promising data input sources for GIS. In this stage Digitization (A conversion process which converts paper maps into numerical digits that can be stored in the computer. Digitizing simplifies map data into sets of points, lines, or cells that can be stored in the GIS computer) is carried out. There are two basic methods of Digitization : Manual Digitizing & Scanning.

II) DATA COMPILATION:

Following the digitization of map features, the user completes the compilation phase by relating all spatial features to their respective attributes, and by cleaning up and correcting errors introduced as a result of the data conversion process. The end results of compilation is a set of digital files, each accurately representing all of the spatial and attribute data of interest contained on the original map manuscripts. These digital files contain geographic coordinates for spatial objects (points, lines, polygons, and cells) that represent mapped features.

III) DATA STORAGE (GIS DATA MODELS):

Once the data have been digitally compiled, digital map files in the GIS are stored on magnetic or other digital media. Data storage is based on a Generic Data Model that is used to convert map data into a digital form. The two most common types of data models are Raster and Vector. Both types are used to simplify the data shown on a map into a more basic form that can be easily and efficiently stored in the computer.