GIS: The Essentials - Sampling Spatial Units for Agricultural Surveys - page 49

Chapter 3
GIS: The Essentials

3.1 Introduction

Powerful tools such as databases have vastly increased the dissemination of data
between users that have different interests and needs. A database can be defined as a
set of data that has a regular structure and is organized in such a way that a computer
can easily find desired information. Data are a collection of distinct information that
have been organized in some specific way, and are used in analyses or to make
decisions. A database can generally be viewed as a collection of records, each of
which contains one or more fields regarding some object. Several basic types of
database models have been developed. The spatial database is a particular type of
database. As stated by Shekhar et al. ( 1999 ), it is aimed at the operational and
efficient management of data related to a space such as the physical world (i.e.,
geography, urban planning, astronomy), parts of living organisms (anatomy of the
human body), and engineering design (i.e., very large scale integrated circuits, the
design of an automobile).
A geographical information system (GIS) is a spatial database that has become
important in many scientific disciplines. It has fostered a greater integration
between the two fields of geography and statistics. GIS is no longer a niche tool,
but represents a modern technology that influences many aspects of research.
In recent years, the Internet and World Wide Web have completely transformed
the role of geographical information in society. The general public is now increas-
ingly familiar with digital geographic data and remote sensing, through sites such as
Google Earth (Goodchild 2007 ).
Several definitions of GIS can be found in the literature. Aranoff ( 1991 ) believes
that GIS is any set of procedures, both manual and automatic, that are used to store
and transform geo-referenced data. Cowen ( 1990 ) argued that GIS is a system for
decision support, and involves the integration of geo-referenced data in a context of
problem solving. Burrough ( 1986 ) states that GIS is a set of tools to capture, store,