What is a GIS: Components and Disciplines (Especially for GATE-Geospatial 2022)

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GIS is a system where the data is represented in spatial context, i.e.. in the form of maps. Its key applications are in intelligent decision making, planning and exploration.

Technically GIS stands for “Geographical Information System.” Simply put GIS is a set of practices and research which allows us represent data on map. For example, look at this data:

Picturizing the World

In very simple terms we can say GIS is picturizing information on earth. Rather than saying population of the states of USA are so and so, we can simply draw the map of USA and mark the highly populated areas versus less populated areas.

Rather than showing information as a table:

US State Population Data
California38,332, 521
Texas26,448, 193
New York19,651, 127
Florida19,552, 860
Illinois12,882, 135
Pennsylvania12,773, 801
Ohio11,570, 808
Georgia9,992, 167
Michigan9,895, 622
North Carolina9,848, 060
New Jersey8,899, 339
Virginia8,260, 405
Washington6,971, 406
Massachusetts6,692, 824
Arizona6,626, 624
Indiana6,570, 902
Tennessee6,495, 978
Missouri6,044, 171
Maryland5,928, 814
Wisconsin5,742, 713
Minnesota5,420, 380
Colorado5,268, 367
Alabama4,833, 722
South Carolina4,774, 839
Louisiana4,625, 470
Kentucky4,395, 295
Oregon3,930, 065
Oklahoma3,850, 568
Connecticut3,596, 080
Iowa3,090, 416
Mississippi2,991, 207
Arkansas2,959, 373
Utah2,900, 872
Kansas2,893, 957
Nevada2,790, 136
New Mexico2,085, 287
Nebraska1,868, 516
West Virginia1,854, 304
Idaho1,612, 136
Hawaii1,404, 054
Maine1,328, 302
New Hampshire1,323, 459
Rhode Island1,051, 511
Montana1,015, 165
Delaware925,749
South Dakota844,877
Alaska735,132
North Dakota723,393
District of Columbia646,449
Vermont626,630
Wyoming582,658

We can depict this information on charts using software like excel.

Tabular Data of Population of US States Represented as a Bar …

Figure 1:

However for geographical or spatial data, such a graph is not very useful. We can use spatial GIS techniques to map such geographical data to appropriate locations on a map:

Tabular Data of Population of US States Geo Referenced and R …

Figure 2:

Components of GIS

Going with our analogy with an excel chart, let՚s understand the components involved in completing a simple GIS task. In creating the excel chart following components were used

  1. The population data
  2. A database manager, our data was managed in excel itself.
  3. A software (again excel) which we used to represent the data as chart.

Similarly, in completing a GIS task, we also have corresponding components.

  1. The population data. This data is spatial, i.e.. it is referenced to some location on the earth.
  2. The data involved is usually so large we need a dedicated piece of software (or sometimes also dedicated hardware) called “database management system.” Think for example of the infinite locations on the earth and their climate data.
  3. A GIS software which can read the data from the database and then using specialized algorithms match that data to corresponding latitude and longitude on a map.

Disciplines in GIS

As we can see, Geographical Information System (GIS) includes two distinct disciplines

  • Geography
  • Information system

Geographic Information (i.e.. spatial information) is information that can be associated with a place name, a street address, a zip code, or coordinates of latitude and longitude. We say that such information is or can be geo-referenced. Geography allows us to collect spatial data, maybe as change over time.

Such data can then be analyzed using Information Systems. Such spatial data can be simply represented as maps like we did earlier. However, to make things more interesting, we can analyze this spatial data using advanced statistics and mapping techniques and come up with interesting patterns, these patterns are then used for planning and decision making. For example changes in land use patterns can be used drive the development or growth of cities.

GIS is a system that captures, manipulates, analyzes, manages and presents spatial and geographical data.

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