Many definitions of GIS have been
suggested over the years, such as "a container of maps in digital
form", "a computerized tool for solving geographic
problems", "a tool for performing operations on geographic
data that are too tedious or expensive or inaccurate if performed by
hand" (Longley, et al, Geographic Information Systems and Science,
2001). Let's look at some of the definitions given by the professional
(United States Geological Survey): In the strictest sense, a GIS is a
computer system capable of assembling, storing, manipulating, and
displaying geographically referenced information, i.e. data identified
according to their locations.
Science Research Institute): GIS is a system of
computer software, hardware and data, and personal to help manipulate,
analyze and present information that is tided to spatial data.
INHS (Illinois Natural History Survey): A Geographic Information
System (GIS) is an organized collection of computer hardware, software,
geographic data, and personnel designed to capture, store, update,
manipulate, analyze, and display all forms of geographically referenced
information. This System allows users to perform very difficult, time
consuming, or otherwise impractical spatial analyses.
In general, we could derive the
practical definition of GIS as a computerized system designed to dealing
with the collection, storage, manipulation, analysis, visualization and
displaying geographic information. GIS is a tool to perform the spatial
analysis which will put insight to the activities and phenomena carrying
Geographic Information Science (GIScience) is advocated
to address are a set of intellectual and scientific questions which go
well beyond the technical capabilities of GIS.
The concept was first advocated by Michael Goodchild.
a pressing need to recognize and develop the role of science in GIS.This
is meant in two senses. The first has to do with the extent to which GIS
as a field contains a legitimate set of scientific questions, the extent
to which these can be expressed, and the extent to which they are
generic, rather than specific to particular fields of application. ...
The second sense has to do with the role of GIS as a toolbox in science
generally -with GIS for science rather than the science of GIS." (Goodchild,
Spatial Information Science, 1990)
Thinking about the
uniqueness of the spatial data, their location based characteristics,
their spatial dependence, Goodchild proposed the contents for GIScience,
such as data collection and measurement, spatial statistics, theories of
spatial data, data structures, algorithms and processes, display and
analytical tools. (Spatial Information Science, 1990)
It is known that the
information science studies the fundamental issues arising from the
creation, handling, storage, and use of information. So,
similarly, we could infer that GIScience should also study the
fundamental issues specifically arising from the special set, geographic
GIsystem is part of the
Geographic Information whole, which also includes the fundamental issues
of GIsicence. (Longley, Geographic Information System and Science,
What is GIService?
GIService is the kind of
services dealing with the geographic information, such as the design and
development of the GIS, geographic information retrieval, analysis, etc.
For example, MapQuest (www.mapquest.com) provides a routing service for
people to find the best driving route between two points.
is GISystem developed?
The first GIS, Canada
Geographic Information System was developed in mid-1960s to identify the
nation's land resources and their existing, and potential
In the late 1960s, US Bureau of the Census created the DIME program
(Dual Independent Map Encoding) for all US streets to support automatic
referencing and aggregation of census data.
In late 1970s, Harvard University's Laboratory for Computer Graphics and
Spatial Analysis developed a general-purpose GIS (ODYSSEY GIS).
The first automated cartography developments occured in the 1960s, and
by the late 1970s most major cartographic agencies were already partly
GIS began to take off in the early 1980s, when the price of computing
hardware had fallen to a level that could sustain a significant software
industry and cost-effective applications.
are the major components of GISystem?
According to the ESRI, the
major components of GIS is hardware, software, data, people, procedure
Hardware, is the
devices that the user interacts directly in carrying out GIS
operations, such as the computer, digitizer, plotter, etc.
Software, normally runs
locally in the user's machine, also supports user to carry out
multiple spatial analysis and management.
Data, which is quite
critical to GIS, contains either an explicit geographic reference,
such as a latitude and longitude coordinate, or an implicit
reference such as an address, postal code, census tract name, forest
stand identifier, or road name.
People is most active
components dealing with the design, programming, operation and
management of GIS.
Procedure, more related
to the management aspect of GIS, is referred to lines of reporting,
control points, and other mechanism for ensuring the high quality of
Network allows rapid
communication and sharing digital information. The internet has
proven very popular as a vehicle for delivering GIS
are data sources of GISystem?
scanning of maps
Use the digitizer to transform the
information from analog format, such as a paper map, to digital
format, so that it can be stored and displayed with a computer . Or
use scanner to convert the analog paper map to computer-readable
Image data includes satellite images, aerial photographs and other
remotely sensed or scanned data, which are in the raster form.
Remote sensing has become a more and more important data source for
data entry including Global Position System (GPS)
Surveying field data which measure the distance and angle to decide
the location of other points could also be transferred into the
GISystem. GPS is a set of hardware and software designed to
determine accurate locations on the earth using signals received
from selected satellites. Location data and associated attribute
data can be transferred to mapping and GISystem.
Transfer data from existing
data are obtained already in digital format from Government Agencies
such as Australian Geological Survey Organisation http://www.agso.gov.au
, the Australian Survey and Land Information Group (AUSLIG) http://www.auslig.gov.au
, and other sources. (Please refer to the WebResource page for available online data provider.)
Basic Data Model in GISystem?
Vector data model
Vector data represents the locations of the discrete objectives
by points, lines and areas.
Raster data model
Continuous numeric values, such as elevation, and continuous
categories, such as vegetation types, are represented using the
raster model. Raster model divides the entire study area
into a regular grid of cells in specific sequence, each cell has a
unique value representing different types.
is Different Kinds of GISystem Software?
A modern GIS software system
comprises an integrated suite of software components, including end user
applications, geographic tools and data access components. GIS software
packages could be classified as six groups based on the functionality
and type. (Longley, Goodchild, et al, Geographic Information Systems and
The distinctive features of professional GIS include data
collection and editing, database administration, advanced
geoprocessing and analysis, and other specialist tools, such as ESRI
ArcInfo, Samllworld GIS.
Desktop GIS focus on data use, rather than data creation, and
provide excellent tools for making maps, reports, and charts.
Well-know examples include ESRI ArcView, Intergraph GeoMedia,
MapInfor professional, Clark Lab's Idrisi, etc.
Hand-held GIS are lightweight systems designed for mobile and
field use, such as Autodesk Onsite, ESRI ArcPad, and Smallworld
Component GIS are tool kits and used by knowledgeable
programmers to create focused applications. Examples include Blue
Marble Geographic GeoObjects, and MapInfo MapX.
GIS viewer are able to display and query popular file formats, such
as ESRI ArcExplorer, Intergraph's GeoMedia, and MapInfo's ProViewer.
Internet GIS focus on display and query applications, as well as
maping. Examples include Autodestk MapGuide, ESRI ArcIMS, Intergraph
GeoMedia Web Map, and MapInfo MapXtreme.