What is Geographic Information System (GIS) ?
Geographic Information Systems (GIS) uses special data visualization techniques for analysis and display of data for planning and decision. It is a special category of DSS which represents the data in the form of digitized maps.
Information means that the data in GIS is organised and produces useful knowledge in colored maps, images, statistical graphics, tables and different on screen activities. The use of the word system means that it is made up of many interrelated and linked components with various functions. There are many business decisions for which geographic location is very important.
Geographic Information System Example, choice of location for opening of new store or deciding on which area requires most police forces. In this case, Geographic Information System (GIS) provides the best support in processing location data and coming up with the output.
Meaning of Geographic Information System
Geographic Information System (GIS) brings together hardware, software and data to capture, manage, analyse and display all type of geographically referenced information.
Thus, it can be said that geographic information system (GIS) helps in capturing, storing, analyzing, managing and presenting data which is linked to geographical location.
For example, a housing developer can use GIS to take business decisions regarding investment. She/he may use GIS to study population growth areas which are highlighted by varying colors according to growth percentage over last few years. Using this information developer may decide where to invest in order to help his business grow.
Purpose of Geographic Information System
- It helps in decision-making on the basis of spatial data. For example, an engineering geologist uses GIS for studying the slope stability conditions and taking a decision on the best new route.
- Aids in general research.
- It gathers and works on spatial data as part of database management.
- It produces both standard as well as customized cartographic representation of spatial data.
Sub-Systems of Geographic Information System
GIS includes following three main elements :
- Computer hardware
- Computer programs
- Data
Figure depicts the five major sub-systems of GIS / Components of GIS :
1) Input :
This handles the creation of image which is based on GIS from multi-geo datasets.
2) Management :
This is required for efficient storage, retrieval and database management.
3) Processing :
This includes data manipulation, feature enhancement and classification, etc.
4) Display :
This refers to the display and product generation.
5) Output :
This includes the thematic maps, images etc. produced to be used by other applications.
Capabilities of Geographic Information System (GIS)
The functions of GIS can be enumerated below as :
1) Organisation :
Data organisation is of fundamental importance as large amount of data collected must be organised in different schemes to make it feasible for use by different. applications. Unless this is done, useful information cannot be extracted. Data models are the different schemes used to organise data. Geographic Information System data are organised according to its spatial location. Data models use both spatial and non spatial attributes for organizing observations.
2) Visualization :
Visualization is attained in GIS with use of coloring, shadowing, perspective and other such specialized methods.
3) Queries :
Data queries are an essential part of Geographic Information System. This is a way of data retrieval which is carried out on existing GIS database or new data resulting from data analysis. This is a useful tool in GIS analysis to check data quality and the results which have been found. Geographic Information System satisfies the following queries :
i) About Location :
The existence at a particular location.
ii) Condition :
This is opposite to the first and uses spatial analysis to provide location of a specific thing.
iii) Pattern :
This query is more sophisticated and important.
For example, one might want to know about the discrepancies in an area over a set period of time.
iv) Trends :
This query involves location as well as conditions and aims to find the variation in an area within a specific time.
v) Modelling :
This query is asked to establish what changes take place when some alteration is done to an existing network.
For example, if a new road is added to existing network or if toxic substances seep into ground water or the local water supply network.
4) Combination :
Combination refers to the process of combining spatial data layers (data integration) and implemented by visualizing composite displays of different kinds or with integration models which create new map from two or more existing maps. This is necessary for conclusive interpretation as spatial phenomenon do not become apparent when individual spatial data is examined in isolation.
5) Prediction :
This is a research tool to discover possible outcomes with a specific set of assumptions. This is usually done to examine the performance of a model.
6) Basic Notations :
GISs are the information systems which provide functionality and tools for collecting, storing, retrieving, analyzing, and displaying geographic information.
Features, events, and activities with spatial components are represented as points, lines, polygons, nets or links to form geographical database under Geo-relational schemes. The geometrical part is described by co-ordinates series and is connected through feature code with the attributes tables which stores the non spatial information (like properties, symbolism, etc.).
7) Analysis :
Polygon overlay with logical operation, buffering in vector maps, interpolations, zoning, and simplified network analysis are comprised in spatial analysis in GIS. This helps in getting meaning out of data. Data analysis is done with the help of measurements, statistical computations, fitting values to data models and other operations. In GIS, analysis of spatial data is termed as spatial analysis.
For example, the area cross tabulation of two maps leads to useful conclusion about inter-relationship between two maps. In statistics, however, spatial coordinates do not play any direct role. Instead, spatial analysis here(statistical literature), often mean analysis involving spatial location.
Geographic Information System Software
Various software applications may be used for accessing, transferring, transforming, overlaying, processing and displaying geographic information. Custom software is used by government and military departments as well as open source products like GRASS. Sometimes, specialized products are also developed for specific requirement. There are free tools available to view GIS data. However, public access to geographic information is dominated by online resources like Google earth and interactive web mapping.
Geographic Information System processing software is utilized for data preparation within Geographic Information System (GIS) itself. This implies that the raw geographic data is transformed into a format which can be used by GIS products.
The software transforms raster and vector data of varying datum's, grid system or reference system into a consistent image. The software analyses changes occurring with time in a specific area.
For professional analysis and presentation of GIS data, this software is crucial. ArcGIS family of ESRI GIS applications Small world, Civil Designer, XMap and GRASS are all examples of GIS software.