GIS: The Essentials - Sampling Spatial Units for Agricultural Surveys - page 50

extract, process, and represent spatial data in the real world. The Environmental
Systems Research Institute (ESRI 1990 ) defines GIS as
“an organized collection of computer hardware, software, geographic data, and personnel
designed to efficiently capture, store, update, manipulate, analyze, and display all forms of
geo-referenced information”.

In essence, we can refer to a GIS as a computerized information system that
integrates data, hardware, software, and the global positioning system (GPS) to
assist a researcher in the analysis and display of geographically referenced infor-
mation. Furthermore, GIS can be seen as a form of management system database,
capable of handling the positions of elements in a territory, which is integrated with
query and visualization software components.
Today, GIS applications are found in many public and private sectors. They
support analyses and studies on the distribution and correlation of different phe-
nomena. The geographic component is an essential tool for the proper comprehen-
sion of reality. GISs allow us to effectively describe relationships between different
variables, which may otherwise be hidden and invisible. The geographical position
includes information that constitutes an enrichment of the data.
The applications of GISs are varied. They include: the analysis and assessment
of environmental, seismic, and hydrological risks; the analysis of routes and
infrastructure (e.g., road traffic, and routes for moving goods and people); the
analysis of flows for geological studies or epidemiology; the regional analysis
system, which is a complete representation of various components of a territory
such as morphology, geology, and demographics; the monitoring and control of a
territory using maps and orthophotos (see Chap. 4 ); highlighting changes over time
and the evolution of a given geographical area; military strategies; and marketing
strategies to highlight and diversify into different groups of potential consumers.
Generally, a GIS tool incorporates five key elements: hardware, software, users,
procedures, and data (see Fig. 3.1 ).
The computer that operates the GIS represents the hardware. The software
provides tools to store, analyze, and display geographic information. Key compo-
nents of the software are tools for the inclusion and manipulation of geographic
information, the database management system, and tools for research, analysis, and
data visualization. A GIS would be meaningless without the people who manage
the system and develop projects. GIS users range from experts to occasional users.
A GIS system must be structured in a coherent way, with operational procedures
specific to each organization. The most important component of a GIS is the data,
which contains four elements: geographical position, attributes, spatial relation-
ships, and time.
The aim of this chapter is to review the main properties of GIS and, in particular,
those that are used in the agricultural field. For an exhaustive description of GIS
characteristics, the interested reader can see, for example, K¨hl et al. ( 2006 ), Liu
and Mason ( 2009 ), Neteler and Mitasova ( 2008 ), O Sullivan and Unwin ( 2010 ),

Goodchild and Longley ( 2013 ), and Sect. VII of the Handbook of Regional Science
(Fischer and Nijkamp 2013 ).

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