Friday, 25 November 2016


A geographic information system (GIS) is a computer system for capturing, storing, checking, and displaying data related to positions on Earth's surface. GIS can show many different kinds of data on one map. This enables people to more easily see, analyze, and understand patterns and relationships. see importance after the break...

Why Is GIS Important? ... A GIS is a computer system designed to capture, store, manipulate, analyze, manage, and present a variety of spatial and geographical data. GIS technology is often used in urban planning, and impacts people living in the area in many ways.

The Uses of GIS
Summarized below are some of the more common and basic uses of GIS.

Mapping Data
The central function of a geographic information system is to provide a visual representation of data.  It is estimated that 80% of the data we consider has a geospatial element of some form.  GIS provides a means for that data to be stored in a database and then represented visually in a mapped format.  Simply understanding where things are is a first step in understanding spatial patterns and relationships.

Proximity Analysis

A proximity analysis is an analytical technique that is used to define the relationship between a specific location and other locations or points that are linked in some way.  It is used by many commercial organisations to identify sites suitable for business outlets.  The technique will consider different factors such as social and economic demographics and the presence of competitor outlets.  For an accurate proximity analysis the various themes to be used must all use the same referencing system otherwise accuracy may suffer.


A technique called buffering is commonly used with proximity analysis to indicate the sphere of influence of a given point.  Buffering involves creating a zone around a given point, line, or polygon (area) of a specified distance.  Buffering is useful for creating a zone around a given geographic feature for further analysis using the overlay method.  For example, a 1000′ buffer could be generated around a school to then use overlay analysis to find out how many libraries are within 1000′ of that school.


Find Clusters

Using multiple algorithms it is possible to select a group of unrelated points on a theme that match a set of criteria.  A cluster could include members where distance between them is less than a specific amount or areas where there is density of points greater than a specific level.  Typically a GIS will require multiple levels of iteration before the correct algorithms are identified.

Find Nearest

A technique that can be used to measure the distances between a point and the edge of a specific element that has been defined as a polygon using vector points.   Nearest neighbor algorithms have been the subject of intense research since the 1980s and new approaches were defined by academics such as Benezecri and Juan in 1982.  The algorithm defined focuses on identifying points that are either maximal, minimal or median members of the data set.

Location Analysis

The technique best used to identify a location for a new retail outlet.   The technique has been developed from theoretical methods used to explain observed conditions to an algorithm for identifying optimal locations.  The algorithms used tend to focus on either maximal, minimal or median members of a given dataset.