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Geographic Information Systems and Science

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Geographic Information Systems and Science

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GEOGRAPHI C I NFORMATI ON
SYSTEMS AND SCI ENCE
GEOGRAPHI C I NFORMATI ON
SYSTEMS AND SCI ENCE
PAUL A LONGLEY
University College London, UK
MICHAEL F GOODCHILD
University of California, Santa Barbara, USA
DAVID J MAGUIRE
Environmental Systems Research Institute, Inc., Redlands, USA
and
DAVID W RHIND
City University, London, UK
JOHN WILEY & SONS, LTD
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Copyright # 2001 by John Wiley & Sons, Ltd.
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Paul A Longley, Michael F Goodchild, David J Maguire, and David W Rhind have asserted their rights under
the Copyright, Designs and Patents Act, 1988, to be identi®ed as the authors of this work.
All Rights Reserved. No part of this publication may be reproduced, stored in a retrieval system, or
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Library of Congress Cataloging-in-Publication Data
Geographic information systems and science / Paul Longley . . . [et al.].
p. cm.
Includes bibliographical references.
ISBN 0-471-49521-2 (alk. paper)ÐISBN 0-471-89275-0 (alk. paper)
1. Geographic information systems. 2. Problem solving. I. Longley, Paul.
G70.212 .G44553 2001
910
0
.285Ðdc21 2001017870
British Library Cataloguing in Publication Data
A catalogue record for this book is available from the British Library
ISBN 0-471-49521-2 (cloth)
ISBN 0-471-89275-0 (paper)
Typeset in 8.5/10pt Lucid Sans from the authors' disks by C.K.M. Typesetting, Salisbury, Wiltshire.
Printed and bound in Great Britain by Bath Press Ltd.
This book is printed on acid-free paper responsibly manufactured from sustainable forestry,
in which at least two trees are planted for each one used for paper production.
CONTENTS
Foreword vi
Preface vii
List of Acronyms xvii
Introduction 1
1 Systems, Science, and Study 1
2 A Gallery of Applications 27
Principles 59
3 Representing Geography 59
4 Georeferencing 79
5 The Nature of Geographic Data 97
6 Uncertainty 123
7 Generalization, Abstraction, and Metadata 143
Techniques 163
8 GIS Software 163
9 Geographic Data Modeling 183
10 GIS Data Collection 205
11 Creating and Maintaining Geographic Databases 225
12 Visualization and User Interaction 247
13 Geographic Query and Analysis: From Data to Information 277
14 Advanced Spatial Analysis 303
15 Uncertainty, Error, and Sensitivity 325
Practice 345
16 GIS and Management 345
17 G-business: GIS Assets, Constraints, Risks, and Strategies 369
18 Operational Aspects of GIS 397
19 Success through GIS Partnerships at Local, National, and Global Level 413
20 Epilog 437
Index 449
v
These guys must be mad. First they invite me to
write a part of their ``Big Book 2'' on GIS. In it I
was the only one out of the ®ve luminaries who
broke ranks and told readers anything useful. All
of those intellectuals (myself excepted) presented
a cosy conspiracy that GIS was wonderful, and
academics and government people would lead us
to the promised land. That's not the way the world
is, folks ± as I said.
Despite that, Messrs Longley, Goodchild,
Maguire, and Rhind have invited me ± a lowly
consultant in the backwoods of GIS ± to do an
introduction to their new book for students and
practitioners. I've now met these guys and they
may not be as crazy as I ®rst thought. It helps
that they drink a little beer (one of them drinks a
lot). But the clincher is that their book is better
than the opposition, most of which is produced
by techno-freaks or academics with little contact
with the reality. Jeez, they've even used
applications from the ``real world'' as they call it,
which looks to me to be in the same orbit as Planet
Lobley. Mind you, it's not perfect. I like the idea
that there are some principles, even maybe
science, behind this stuff. ``GIS as button-
pushing'' is not a smart view of how to change
the world. I also think that having stuff on
business makes sense ± that's where things get
done, where people take risks, and make (and
lose) their money. It's also where any youngster
these days should aim to work. But I guess I'm
not as convinced as these guys that academia
and government are wising up and becoming
more business-like ± seems to me that the
opposite is happening as business is being
loaded with more and more of the bureaucracy of
government!
So guys, I reckon you got about 70% to 80% right
in this newbook of yours. That's quite a mite better
than the others I've seen ± my rating for them is
between 20%, and 40%. I wish you well with it
but suspect that you will not dare publish this
foreword! That's unless you left it too late to
ask some academic or bureaucratic sycophant
instead.
Joe Lobley
Senegal, September 2000
FOREWORD
vi
There are perhaps 100 other books on geographic
information systems (GIS) now on the world
market. To the best of our knowledge, there is no
other one like ours. One reason for that is that
most treat GIS as a largely technical issue. This is
re¯ected in the skills of existing GIS staff and the
junior and middle level jobs they occupy. But our
philosophy differs more profoundly than simply
believing that there is too much emphasis on the
technology. We see GIS as providing a gateway to
science and problem-solving. Our philosophy is
summarized below.
OUR APPROACH
The basic operations of GIS provide secure and
established foundations for analysis, although
the technology is still evolving rapidly (especially
in relation to the Internet, its likely successors,
and spin-offs). Better technology will remain a
necessary condition for achievement of cheaper,
faster GIS and better interoperability ± but it is far
from a suf®cient condition for successful applica-
tion of such systems.
GIS is fundamentally an applications-led tech-
nology, yet science underpins successful applica-
tions. Effective use of such systems is impossible
if they are simply seen as black boxes producing
magic. Understanding the imprecision and un-
certainty of our representations of the world, and
the consequences of our operations on them, is
essential for everything except the most trivial
use of GIS. Empirical analysis of the real world
can be a messy and analytically inconvenient
business and so the science of real-world
application is the dif®cult kind ± it can rarely refer
to apparently universal truths, such as the laws of
gravity. Rather it is one founded on a search for
understanding and predictive power in a world
where human factors interact with those relating
to the physical environment. Social science and
natural science are part of what we embrace. In
addition, ethics and esthetics ± the basis of the
most effective graphic displays ± can also play an
important role.
Geographic information is central to the
practicality of GIS. If it does not exist, it is
expensive to collect, edit, or update. If it does
exist, it cuts costs and time ± assuming it is ®t
for purpose, or good enough for the particular
task in hand. It underpins the rapid growth of
trading in geographic information (g-commerce).
It provides possibilities not only for local business
but also for entering new markets or for forging
new relationships with other organizations. But
it is a foolish individual who sees it only as a
commodity like baked beans or shaving foam. Its
value relies upon its coverage and on the strengths
of its representation of diversity, on its truth within
a constrained de®nition of that word, and on its
availability.
Few of us are hermits. The way in which
geographic information is created and it and GIS
are exploited affects us as citizens, as owners of
enterprises, and as employees. It has increasingly
been argued that GIS is only a part ± albeit a
part growing in importance and size ± of the
Information, Communications, and Technology
(ICT) industry. That is a limited perception, typical
of the ICT supply-side industry which tends to see
itself as the sole progenitor of change in the world
(wrongly). It is actually much more sensible to take
a balanced demand- and supply-side perspective:
GIS and geographic information can and do under-
pin many operations of many organizations, but
how GIS works in detail differs between different
cultures. The fact that few Japanese streets have
names creates a very different navigation
vii
PREFACE
problemthere compared with North America. Such
underpinning is true whether the organizations
are in the private or public sectors. Seen from this
perspective, management of GIS facilities is crucial
to the success of these organizations ± businesses
as we term them later. The management of the
organizations using our tools, information,
knowledge, skills, and commitment is therefore
what will ensure the ultimate local ± and hence
global ± success of GIS. For this reason we devote
an entire section to management issues. But in so
doing we go far beyond how to choose, install, and
run a GIS. That is only one part of the enterprise.
We try to show how to use GIS and geographic
information to contribute to the business success
of your organization, and have it recognized as
doing just that. To achieve that, you need to
know what drives organizations and how they
operate in reality in their business environment.
You need to know something about assets, risks,
and constraints on actions ± and how to avoid the
last two and nurture the ®rst. And you need to
be exposed ± for that is reality ± to the inter-
dependencies in any organization and the trade-
offs in decision-making.
Success with GIS only comes from
understanding and familiarity with science,
technology, people, and institutions.
Expertise in one area is not enough.
OUR AUDIENCE
As a team, we have already produced one very
different book ± the second edition of the ``Big
Book'' of GIS. This reference work on GIS (Longley
et al 1999) contains 72 chapters written by many
of the best GIS people in the world. It was designed
for those who were already very familiar with GIS,
taking them to the frontiers of research and
practice across a huge range of topics. It was not
designed as a book for those being introduced to
the subject.
This one is. We have in mind those studying at
an intermediate stage in the huge range of under-
graduate courses that are available throughout the
world. The coupling of the book to the second
edition of the Big Book (and also its predecessor,
Maguire et al 1991) also makes it of use to
postgraduates in GIS. Such users might desire an
up-to-date overview of GIS to locate their own
particular endeavors, or (particularly if their
previous experience lies outside the mainstream
geographic sciences) a fast track to get up-to-
speed with the range of principles, techniques,
and practice issues that govern real-world
application. We have also directed it towards the
busy professional, who has many demands on his
or her time but who has heard something of this
new wonder and needs to gain familiarity with the
subject in a no-nonsense way.
This is not just a textbook for mechanics. There
are plenty of those already (some of them good).
The market for GIS is huge yet fast-growing and
most of the new users do not consider
themselves principally to be technicians. We are
convinced of the need for high-level under-
standing and so our book deals with ideas and
concepts ± but also with actions. In geographic
science, for instance, you need to be aware of the
complexities of interactions between people and
the environment. In management, you cannot
become competent without practice, informed by
a wide range of knowledge about issues which
might impact your actions. Success in
management ± and in GIS more generally ± often
comes fromdealing with people, not machines. We
seek to prepare you for such situations.
Because of the rapid annual growth rates of
GIS, there are far more people new to it than
there are existing experts. The two groups
need different material.
LEARNING OR BEING TAUGHT?
As the title implies, this is a book about geographic
information systems, the practice of science in
general, and the principles of geographic infor-
mation science (GIScience) in particular. But it is
even more than that. It is a deliberate attempt ±
an early one ± to recognize and exploit the fact
that information and communications technol-
ogies are helping to change the world of learning,
as well as business, government, and science. ICT
is not really about making the old ways better. In
the world of learning, it offers a genuinely different
way, and one which has many advantages and
some disadvantages.
For this reason, we start off by talking about the
purpose of this book ± to make you more capable
of doing certain desirable things. This ability will
come from a greater understanding of the factors
involved, expertise in use of the tools at your
disposal, recognition of the laws of unintended
consequences, and adherence to the set of values
(e.g. professional integrity) by which you operate.
We follow this up with an overview of the kinds of
problems with which GIS and GIScience can help.
First, however, we must recognize the impacts of
technology and other factors on the way we learn
and the ways in which we seek to organize and
change the world.
The general model of education ± at university
level and during in-work training ± is changing.
There are two interrelated reasons for this. The
P R E F A C E
viii
®rst is that injections of knowledge are no longer
the cornerstone of education. The second is that
businesses are becoming a serious player in the
most advanced levels of education, long the
preserve of state or private universities ± and
some universities are increasingly acting like
businesses in how they run their courses.
The transfer of knowledge, suitably codi®ed
and ®tted within widely accepted conceptual
models, was the basis of the old education. That
transfer from teachers to students was part of
an implicit contract subscribed to by both the
teacher and those taught. Two changes of great
importance have occurred. The ®rst is that higher
education in most countries has gone from being
the preserve of the few to the right of the many.
When we authors went to university, for instance,
we were part of only 5±10% of people who
experienced such education; now the average in
the countries surveyed by the Organization for
Economic Cooperation and Development (OECD)
is around 30% and it is over 50% in the USA. Many
of these students are also working part-time as well
as studying and have different requirements from
those full-timers of the past. The second change
is that a rapidly growing amount of information is
readily available via the Internet, ever more cheaply
and easily. In these circumstances, the value added
by universities is to ensure that those being
educated have skills of information retrieval,
sifting, assessment, and analysis, plus the ability
to ferment knowledge from reliable information
and apply it to good effect. Thus we are moving
rapidly from an era where the creation and
inculcation of knowledge was often the primary
focus (frequently through traditional but
sometimes ineffectual methods like the formal
lecture) to one where learning and knowing how
to learn, all achieved between other pressing
concerns, are the prime drivers.
Information ± and sometimes evidence and
knowledge ± are increasingly available on the
Internet. Where to ®nd information, how to
analyze it, and how to assess its quality are
now more important than memorizing it.
This does not mean that there is only one way of
learning or that conversing with a computer is the
only way to achieve educational enlightenment. We
know that different people have different learning
abilities and prefer different learning styles. Whilst
some students rate lectures very highly, those
who are not familiar with extracting meaning
from them often feel alienated. Much the same
occurs in some books written in an old academic
style. Some research has shown computer-based
learning to be the least popular mode. But in a
world where education and learning is a mass
pursuit ± rather than one simply for intellectual
elites ± the bulk of evidence suggests multiple,
non-traditional approaches are more effective
(Table 1). This requires a shift from didactic
teaching to an active experience of learning
through integrating knowledge bases and
analyzing the results, all in the interests of
solving particular problems yet gaining wider
understanding of how to do such tasks better
next time.
In a rapidly changing world, our learning also
needs to be life-long. How best can we ensure
this happens and is successful? To do this, we
need to recognize that learning is also a social
and cultural process, not just a cognitive one.
This leads us to believe that distance-learning
methods on their own are unlikely to be suc-
cessful. It is self-evident that different approaches
work best for different stages in education, as
suggested in Table 1. We may debate the
contents of any one cell in the matrix, but the
bene®ts of tailoring the learning methodology to
the task are certain.
There is no one right way to learn ± different
approaches suit different people at different
times and for different tasks.
Across the world the proportion of people
attending universities is rising. The expenditure
on high-level education is thus large and increas-
ing. It is not surprising therefore that the private
sector sees opportunities, not least because
studies in various countries have revealed that
P R E F A C E
ix
Table 1. A matrix of learning steps and learning/teaching technology (Hills 1999). Crosses show where a
particular technology does not function well for particular educational needs
Live Lab Peer Print Audio Video Computer Computer
teacher work group off-line on-line
Motivation T Â T T T T T Â
Information transfer  T T T T T T Â
Knowledge gestation T T T Â Â Â T T
Assessment T T T T Â Â T Â
Prescription of action T Â T Â Â Â Â T
there are major obstacles to the existing providers
adapting to new ways of operating ± notably the
inertia and complacency exhibited by many staff
in existing universities. Add to this the
recognition by manufacturers of sophisticated
software products that education and training of
their users is crucial to building up a cohort of
skilled, successful (and loyal) customers. And
®nally, in a world where Continuing Professional
Development (CPD) is required to keep people up-
to-date, the opportunities for repeat business are
great. The result is that the private sector sees
education and learning as a golden opportunity.
Manifestations of this range from the private
University of Phoenix ± which commissions
courseware from other suppliers, engages staff
part-time, and makes great use of distance-
learning methods ± to software vendors who run
successful courses on their own software,
preceded by courses on the principles. In GIS,
a number of different approaches to distance
learning and CPD have been taken by private
and publicly funded bodies such as the UNIGIS
consortium, ESRI in its Virtual Campus, and at
Pennsylvania State University.
How does this book ®t with the new learning
paradigm?
This is not a traditional textbook because:
* GISystems and GIScience do not lend them-
selves to traditional classroom teaching. Only
by a combination of approaches can such
crucial matters as principles, technical issues,
practice, management, ethics, and accountabil-
ity be learned. Thus the book is complemented
by a Web site and by a range of other online
resources, including modules specially written
to accompany the book.
* It attempts for the ®rst time to bring the
principles and techniques of GIScience to
those learning about GIS for the ®rst time ±
and as such represents a major new stage in
the evolution of GIS.
* The very nature of GIS as an underpinning
technology in huge numbers of applications,
spanning different ®elds of human endeavor,
ensures that learning has to be tailored to
individual or small-group needs.
* We have recognized the need to be driven by
real-world needs. Hence a variety of applica-
tions and case studies are threaded through
the text.
* We have linked our book to online learning
resources throughout, notably the ESRI Virtual
Campus.
SCIENCE, GOVERNMENT, BUSINESS, AND THE
PROBLEMS AMENABLE TO GISCIENCE
Since this book is about GIScience, anything which
changes the nature of science is relevant to us. The
environment of GIScience is provided by GIS which
has, since its inception in the 1960s, frequently
been seen and used as a method of solving real-
world problems. Thus any developments in
problem-solving within business or government
are also relevant to us and need to be re¯ected
in the structure and contents of the book. What
is happening more generally in business ± the
largest employer in most countries ± is
particularly crucial to us. As it turns out, there is
something of a convergence between contem-
porary approaches to problem-solving in science,
business, government, and society. This con-
vergence and the (diminishing) tensions between
these groups are now explored and the
consequences for the book set out.
GIS, and Mode 1 and Mode 2 science
In recent years, the combined effect of
technological and societal factors has begun to
re-shape science. Much science has become
multinational. Growing distrust of stereotypical
scientists in white coats has led to demands
for much greater openness and accountability.
Again, of course, there is no unanimity about
what is happening in detail but the general
outline of the change is clear. It has been argued
that there are two distinct attitudes to the creation
and use of knowledge, which is the role of science.
Mode 1 approaches still dominate the current
scene and are manifested in subject-based
universities. However, the business/government/
academic convergence is manifested in a Mode 2
approach. Table 2 summarizes the characteristics
of the two modes.
The public understanding of science and
scienti®c understanding of the public are
becoming key issues. Any method of
enhancing communication between the two
groups ± like GIS - is valuable.
Where does this book ®t in? Geography is universal;
all physical phenomena and many abstract ones
demonstrate spatial differentiation. The differen-
tiation is rarely (if ever) random. Patterns are fre-
quently observable if viewed at appropriate levels
of detail (though sometimes these can be spurious
artefacts of the way we carry out our analyses).
More than that, there is some generality about
these geographical patterns. Tobler's First Law
of Geography is presented in Chapter 5, and
P R E F A C E
x
illustrates this neatly. On the face of it therefore,
Geography is a Mode 1 type activity in seeking
universal truth. In practice, that is often far from
the case. The great bulk of GIS applications are
about problem-solving in a particular context
rather than in elucidating general theories or
laws. There are several reasons why much
Geography ± and GIS in particular ± has Mode 2
characteristics:
* It is commonplace to have to work with both
physical science and social and economic
science factors (e.g. in choosing the siting of a
nuclear waste plant). This rarely permits the
formulation of universal laws but draws upon
them.
* Because of this, team working is the norm, with
different members contributing different skills
(and sometimes different value systems).
* There is rarely a single set of objective criteria
with which to measure success. Normally any
GIS analyses and subsequent recommendations
involve accommodating various trade-offs,
each solution having advantages and
disadvantages. Put another way, the success
criteria are not universal ± the team will have
their own means of judging success (e.g.
achievement of a solution through rigorous
application of certain methodologies and the
garnering of adequate data matching the
requirements of any statistical tests). But real-
estate developers, public of®cials, environmen-
tal scientists, non-governmental organizations,
and lay citizens may have quite different
success criteria.
* GIS specialists are very likely to be working in
different subject domains in successive jobs.
* Publication of results is often manifested in
forms other than papers in refereed journals
(e.g. as part of reports, as maps, or as Internet
Web sites).
Given all of this, we should not pretend that we are
always engaged in traditional Mode 1 science. GIS
deals with everything from the universal laws of
physics, through areas of statistical regularity, to
the highly individual. And our results often have to
be acceptable ± or at least defensible ± to different
people with different experiences, different views,
and (sometimes) different vested interests. That
does not mean that we simply produce answers
to order ± we have an ethical commitment to
P R E F A C E
xi
Table 2. The characteristics of Mode 1 and Mode 2 approaches to science (after Hills 1999)
Mode 1 Mode 2
Subject, and publication specialization, and Holistic, not reductionist
fragmentation of knowledge
Curiosity-driven, often blue-skies research Mission-oriented, not blue-skies research ± usually
usually within subject. Objectivity and strategic or applied. Context-driven, not subject-
disinterestedness driven. Service of practical interests involving
subject values
Sets out to produce general laws or statements ± Context-speci®c results ± results must be obtained
but sometimes fails
Impersonal attitudes, open publication, and open Re¯exive philosophy rather than absolute
argument. Progress by conjecture and refutation judgments
Sometimes (though less and less common) the Team-work based, not an individual scholar
work of a solitary scholar
Leads to convergence, consistency, reliability, but Divergent, not convergent
also consolidation of establishment values
Publications may be single- or multi-authored, Multi-authored publications, heterogeneous
homogeneous knowledge bases. Typically published knowledge bases. Some work not published if it
in openly accessible, refereed scienti®c journals ± provides competitive advantage, e.g., for
but often with substantial publication delay exploitation of Intellectual Property Rights. Much
use made of the Internet
Long-established scienti®c method, widely accepted Re¯ects the world outside academia ± the world in
within science community which graduates work
Life-long vocation on part of researchers Professional teams, re-assembled on project basis
produce the best, most objective, and replicable
results possible.
Working in GIS inevitably involves being in
con¯ict with others at different times.
Coping with this involves both scienti®c and
personal skills.
Making governments work better with GIS
Governments still matter. Notwithstanding the
growth of business into traditional areas of public
provision of services like education, governments
at national, state, and local levels have a big
in¯uence on the lives of citizens. Yet many
governments under-achieve, even though they
often have excellent staff. The reasons why this
occurs include outdated organizational struc-
tures, cultures, and remits dating from much
earlier times. Backward-looking organizations
tend to look after their own interests (e.g. in
terms of opening hours, service provision
locations, and what information they require from
their clients). They tend to be relatively self-
contained, minimizing collaboration with other
bodies. In addition, the nature of most
governments is that politicians are appointed to
run their own departments ± but the problems
facing government as a whole are rarely capable
of solution by a single vertically organized
department. For example, reducing poverty in
society has employment, educational, housing,
social security, tax, and (possibly) health, and
transport implications.
Inertia may prevail because there is little
incentive (other than political pressure generated
by elections) to improve. A focus on inputs (e.g. the
budget-setting process is a key activity in most
governmental years) rather than outcomes is
quite common in government. And risk aversion,
sometimes because over-seeing bodies will punish
all failure even if a good risk assessment was
carried out, is very frequent. Rarely in govern-
ment is anyone praised or rewarded for succeed-
ing, but punishment for failure is inevitable and
often public. All this adds up to lower-than-
feasible performance, unresponsiveness to
elected politicians and citizens, and costly
inef®ciencies.
Minimizing these problems is non-trivial, but
many governments across the world have begun
to tackle them. The ways this has been done
include:
* Setting targets, publicizing these, and measur-
ing achievement for different branches of gov-
ernment (which can be effective but tends to
atomize government, minimizing interactions
and fostering the shifting of problems to other
people).
* Creating matrix-like management structures
across government and also rotating staff
from one department to another to propagate
best practice.
* Empowering citizens with information about
what the departments are setting out to achieve
and the background to judge them, rewarding
the departmental successes appropriately.
* Trying to build integrated or ``joined-up'' gov-
ernment by common use of the same electronic
forms and procedures and re-use of informa-
tion wherever it exists, rather than collecting it
and retaining it within silos in each department.
In short, taking a corporate approach to infor-
mation management and to management of the
enterprise as a whole.
Where does GIS ®t into the new approaches to
government? It will be obvious that solving
problems in this domain is not straightforward,
not least because there are usually multiple ob-
jectives and in®nite expectations of government.
Typically in large and complex organizations like
democratically elected governments, some
policies may actually contradict and undermine
others. Certainly the need to establish corporate
approaches across government can easily under-
mine the local autonomy needed when someone
is asked to solve a particular problem. But it is
quite extraordinary how many of these problems
can be eased by appropriate use of GIS. In
particular, use of a common base set of
information, including the topography and key
datasets (environmental, socio-economic,
®nancial statistics, etc.) can be effective in
fostering integrated government. Use of a
common GIS language and an ability to sew
together datasets from many sources and assess
them can be crucial ± in the late 1980s, the
CORINE environmental GIS created for Europe
demonstrated that different sampling and data
creation algorithms ensured that the greatest rate
of environmental change across that continent
often occurred at country boundaries! More than
that, empowering citizens is ever easier ± at least
for those with access to computers ± through
information provided over the Internet. Use of GIS
can make a huge variety of information available in
understandable form to the non-expert citizen. In
addition, some risk assessments can be carried out
effectively within a GIS and reported readily.
In summary, much of government is related to
things happening or not happening in a given area.
As a minimum its success requires consistent,
relevant, and up-to-date information. In a world
P R E F A C E
xii
where more is expected for less, costs must be cut
through reduction in staff time, although the
political process ensures that multiple solutions to
problems with many causes have to be evaluated
and exposed. Given all this, it is no great surprise
that GIS is increasingly widely used at all levels of
government. GIScience may, however, seem
irrelevant in an arena where improvements in
routine decision-making and information
exchange will make things better. In practice, the
science is still central to good governance if only
because it should help us to avoid capricious or
even gerrymandering use of GIS.
Government ``of the people, by the people,
for the people'' is made easier by the
widespread use of GIS.
Meeting business needs with GIS
It seems self-evident that business is primarily
driven by the bottom line. Sometimes this truly is
entirely a short-term affair: stock prices rise and
fall according to quarterly pro®tability in some
industries. But other businesses act on a longer-
term basis. For instance, Amazon.com and many
other .com companies made no pro®ts in their
®rst few years of trading. Even beyond that,
however, many businesses seek to operate in a
way which is sustainable, environmentally
friendly, and takes account of local priorities and
issues. To do so is often good business: the
reputation of a business for integrity, sensitivity,
and fair dealing is hard won and in¯uences
potential customers, yet is easily lost. To abide by
local laws and customs also reduces business
risk. For these reasons, it is grossly simplistic to
see ®rms as simple pro®t-maximizers. They too
need information about business opportunities
and risks and how these are geographically
distributed. Yet they also need to know how to
solve a particular problem at minimum cost but
maximum ef®cacy. The latter does not just mean
a narrow concern with ef®ciency and short-run
pro®tability: it normally means being sensitive to
the opinions of customers and government and
building long-term relationships. One big part
of this is achieved by bringing together the
best available contemporary information and
analyzing it using the best science. It is obvious
that GIS is a superb vehicle to do this.
Making pro®ts is a necessary condition for
success in the private sector ± but not a
suf®cient one for long-term success. Use of
GIS can help to evaluate alternatives,
minimize business risk, share cost, and audit
processes for regulators and citizens'
groups.
SUMMARY
In this preface we have tried to show that there
is growing commonality between the concerns of
business, government, and science. The examples
in the book of problems tackled through GIS have
been chosen deliberately to show this common-
ality, as well as the interplay between
organizations and people from different sectors.
Clearly the concerns and commonality will never
totally coincide. But concerns with effectiveness,
ef®ciency, bringing together information from
disparate sources, acting within regulatory and
ethical frameworks, and preserving a good repu-
tation are all common at the meta-level. For this
reason, this book combines the basics of GIS with
the solving of problems which often have no single,
ideal solution ± the world of business, government,
and Mode 2 science.
There are few absolutes in our world. For
instance, the distinction between Mode 1 and
Mode 2 approaches can be exaggerated: much of
``big science'' is now a team-based endeavor,
often inter-disciplinary and international in scope,
rather than the activity of a lonely scholar in a
traditional discipline. That said, the convergence
noted above is mostly in relation to Mode 2
approaches to knowledge creation or science:
the approaches in government and in business
certainly resemble Mode 2 science rather more
than the Mode 1 variety. The common
characteristics are a search for good solutions
within a particular context, achieved within
available time and budget, and taking account of
all available information (however imperfect) ±
rather than seeking the truth, however long it
takes, and rigid adherence to certain procedures.
At the same time, there are many aspects of Mode
1 science ± the formulation of hypotheses to be
tested, the need to be able to replicate and
demonstrate results, plus an acceptance of the
need to justify and debate results ± which remain
essential. In this book therefore we have sought
to bring in different strands of scienti®c approach
and to be eclectic in dealing with both physical and
social sciences. Throughout the book, and in its
accompanying Web site and associated material,
we have also tried to escape ``silo'' or stovepipe
mentality in tackling real-world problems of
relevance to governments, businesses, and the
citizen alike, and to avoid being constrained by
traditional disciplinary blinkers. We see our
efforts as being to underpin the business
activities of those working in the public and
private sectors ± de®ning ``business'' in its widest
sense.
In short, we have tried to create a book tuned to
the way the world works now, to the way in which
P R E F A C E
xiii
most of us increasingly operate as knowledge
workers, and to our need to face complicated
issues without ideal solutions in our daily lives.
As we have said above, it is obvious that this
book is an unusual enterprise and product. It has
been written by a multinational partnership,
drawing upon material from around the world.
One of the authors is an employee of a leading
software vendor and two of the other three have
had business dealings with ESRI over many years.
Moreover, many of the illustrations and examples
come from the customers of that vendor. We wish
to point out however that neither ESRI (or Wiley) has
ever sought to in¯uence our content or the way in
which we made our judgments, and we have
included references to other software and
vendors throughout the book. Whilst we make
frequent reference to ESRI's Virtual Campus (and
some modules of it have been speci®cally written
around this book), we also make reference to
similar sources of information in both paper and
digital form. We believe we have created
something novel but valuable by our lateral
thinking in all these respects. Whether we actually
have or not is of course for others to judge.
CONVENTIONS USED IN THE BOOK
We use the acronym GIS in many ways in the book,
partly to emphasize one of our goals, the interplay
between geographic information systems and
geographic information science; and at times we
use two other possible interpretations of the
three-letter acronym: geographic information
studies and geographic information services. We
distinguish between the various meanings where
appropriate or where the context fails to make
the meaning clear, especially in Section 1.6 and
in the Epilog. We also use the acronym in both
singular and plural senses, following what is now
standard practice in the ®eld, to refer as
appropriate to a single geographic information
system or to geographic information systems in
general.
We have used a series of devices to aid
navigation of the book, notably through the use
of color and symbols. Each section is color-coded
by a title bar. The header for each box contains an
icon to show whether it is technical, relates to
people or is about applications.
HOW TO MAKE THE MOST OF THIS BOOK
Although the book stands alone as a self-contained
work, we have intended it to be used in conjunction
with the two editions of Geographical Information
Systems. We include speci®c references to
both editions at the end of each chapter and at
points in the text where a reference is particularly
appropriate. Wiley has made chapters and the
bibliography of the ®rst edition available on
the companion Web sites, www.wiley.com/gis and
www.wiley.co.uk/gis. The references give access to
greater depth, and more detail on many core
topics, and also to reviews of more peripheral
topics that we have not been able to cover here.
Boxes, each with distinctive icons, are used to
describe key techniques, to present illustrative
real-world applications, and to summarize the
activities of key individuals in the ®eld.
At the end of each chapter we also include
references to other, easily accessible, books on
special topics. We have not attempted to provide
a complete bibliography because extensive refer-
ence lists appear in both editions of Geographical
Information Systems. There are references after
each chapter to relevant sections of the materials
available online at the ESRI Virtual Campus,
campus.esri.com; links to other relevant online
information; and references to the two Core
Curricula developed by the National Center for
Geographic Information, and Analysis (NCGIA),
both now online. Throughout the book we have
tried to limit references to only the most stable
WWW sites but unfortunately it is inevitable that
some will disappear through time.
We have organized the book in three major but
interlocking sections: after two chapters of
introduction, the sections appear as Principles
(Chapters 3 through 7), Techniques (Chapters 8
through 15), and Practice (Chapters 16 through
19). We conclude with an Epilog (Chapter 20). It
was not always easy to decide whether some
topic belonged in principles or in techniques but
we have tried to separate the persistent principles
± ideas that will be around long after today's
technology has been relegated to the museum ±
from knowledge that is necessary to an
understanding of today's technology and likely
near-term developments. Much of the accum-
ulated knowledge that existed in many cases long
before digital computers, but is now more
important than ever, appears in the Principles
section, such as the map projections invented by
cartographers in centuries past. Some topics
such as uncertainty or spatial interpolation clearly
belong in both and we have discussed them in
general terms as principles and in speci®c terms
as techniques, with cross-references where
appropriate and without unnecessary repetition.
ACKNOWLEDGMENTS
As the book went to press, we were saddened
to hear of the death of Professor John Estes, the
well-known expert in remote sensing. A long-time
colleague of Michael Goodchild at Santa Barbara
and long-standing friend of David Rhind, he made
P R E F A C E
xiv
major contributions to the new global map
(Chapter 19) and to many aspects of the interface
between remote sensing and GIS. We gratefully
acknowledge his support and friendship. At about
the same time we also learned of Ian McHarg's
death. McHarg's method, in which planners
inventory every level of detail about a place and
take this into account in development, is the
basis to what became GIS. Ian McHarg was a long
term associate of, and inspiration to, Michael
Goodchild and will also be sadly missed.
We take complete responsibility for all the
material contained herein. But much of it draws
upon contributions made by friends and
colleagues from across the world, many of them
outside the academic GIS community. We thank
them all for those contributions, and the
discussions we have had over the years. We
cannot mention all of them but would particularly
like to mention the following:
For their input to this project, and for many GIS
discussions over the years: Mike Batty, Clint Brown,
Nick Chrisman, Keith Clarke, Andy Coote, Danny
Dorling, Jason Dykes, Max Egenhofer, Pip Forer,
Andrew Frank, Gayle Gaynor, Richard Harris, Les
Hepple, Sophie Hobbs, Karen Kemp, Chuck
Killpack, Vanessa Lawrence, John Leonard, Bob
Maher, David Mark, David Martin, Scott Morehouse,
Scott Orford, Peter Paisley, Jonathan Raper, Helen
Ridgway, Jan Rigby, Christopher Roper, Garry
Scanlan, Karen Siderelis, David Simonett, Andy
Smith, Roger Tomlinson, Carol Tullo, Dave Unwin,
David Willey, Jo Wood, Mike Worboys.
To Peter Haggett, for guidance (not always
heeded!) as to how to prepare a good textbook.
At University College London, where much of
the artwork was drawn, and the drafts assembled:
Nick Mann, Elanor McBay, Cath Pyke, Sarah
Sheppard.
Our friends in Tuscany: General Facciorusso,
Col Serino, Lt Col Orru, and Captain Bari of the
Italian Geography and Mapping Institute for their
hospitality and for showing us their astounding
maps and books from the 15th century onwards.
At John Wiley: Rob Garber, JimHarper, Lou Page,
and (for guiding the project from conception to
fruition) Sally Wilkinson.
We would be remiss if we did not mention the
contribution of Jack Dangermond, a true visionary,
whose enthusiasm has done much to inspire the
entire GIS enterprise, both at ESRI and around the
world.
We would especially like to thank the following
people for allowing us to use their material:
Academic Press Ltd, Aerial Images Inc./
Sovinformsputnik, the Association of American
Geographers, Autodesk, Richard Bailey, Mike
Batty, Blackwell Publishers, CA Department of
Fish and Game, Martin Callingham, John Colkins
of ESRI and the State of Hawaii for the
background image on the front cover, Tom Cova,
Peter H. Dana, Daratech Inc., Frank W. Davis
of University of California Biogeography Lab.,
DeLorme Publishing Co. Inc., Daniel Dorling,
Durham Herald Company Inc., Earth Science
Department of University of Siena in Italy,
Ecotrust, ERDAS Inc., EROS Data Center, ESRI,
Experian, GDS, the Geographical Magazine, GTCO
Calcomp, Richard Harris, Human Settlements
Research Center of Tsinghua University in China,
Institute of Transport Engineers, Intergraph,
Landmark Information Group, Mitch Langford of
MRRL (University of Leicester), Lawrence Berkeley
National Laboratory, Leica, London Transport
Museum, MapInfo, MapQuest.com Inc., David
Mark, Matrix Directory and Information Services,
Microsoft, NASA/JPL/Caltech, Open GIS
Consortium Inc., C. S. Papacostas, Pearson
Education Ltd, Jesper Persson of Teleadress
Information AB, Pinter Press, Professor J. Radke,
San Parks in South Africa, Ashton Shortridge,
Andy Smith, Taylor & Francis, Henry Tom of
Oracle, USGS Department of the Interior, Richard
Webber, and Marcel de Wit.
Whilst every effort has been made to trace the
owners of copyright material, in a few cases this
has proved impossible and we take this
opportunity to offer our apologies to any
copyright holders whose rights we may have
unwittingly infringed.
Finally, thanks go to our families, especially
Amanda, Fiona, Heather, and Christine, who have
endured so much during the preparation of this
manuscript.
Paul Longley
Michael Goodchild
David Maguire
November 2000 David Rhind
Reference Links
Maguire D J, Goodchild M F, and Rhind D W (eds)
1991 Geographical Information Systems:
Principles and applications. Harlow, UK:
Longman (Text available online from `Links
to Big Book 1' at www.wiley.com/gis and
www.wiley.co.uk/gis).
Longley P A, Goodchild MF, Maguire D J, and Rhind
D W (eds) 1999 Geographical Information
Systems: Principles, techniques, management
and applications. New York, John Wiley.
References
Hills G 1999 The University of the future. In Thorne
M (Ed.) Foresight: Universities in the future,
London: Department of Trade and Industry,
213±232.
P R E F A C E
xv
AA Automobile Association (UK)
ACORN A Classi®cation of Residential Neighbourhoods (UK)
ADRG Arc Digitized Raster Graphics
AGI Association for Geographic Information
AM/FM automated mapping/facilities management
AML Arc Macro Language
API application programming interface
ARPANET Advanced Research Projects Agency Network
AVHRR Advanced Very High Resolution Radiometer
BASIC Beginners All-purpose Symbolic Instructions Code
CAD computer-aided design
CAMA Computer Assisted Mass Appraisal
CASE computer-assisted software engineering
CBD central business district
CD compact disk
CES Centre for Environmental Studies
CGIA Center for Geographic Information and Analysis (North
Carolina)
CGIS Canada Geographic Information System
CGM computer graphics meta®le
CLM collection-level metadata
COM component object model
COGO coordinate geometry
CORBA common object request broker architecture
COTS commercial off-the-shelf
CPD continuing professional development
CSDGM Content Standards for Digital Geospatial Metadata
DBA database administrator
DBMS database management system
DCW Digital Chart of the World
DDL data de®nition language
DEM digital elevation model
DIME Dual Independent Map Encoding
DLG digital line graph
DML data manipulation language
DRG digital raster graphics
DWG drawing
DXF drawing exchange format
EC European Commission
EDC EROS Data Center
EPA Environmental Protection Agency
EPS encapsulated postscript
ERDAS Earth Resources Data Analysis System
EROS Earth Resources Observation Systems
ESRI Environmental Systems Research Institute Inc
EU European Union
FEMA Federal Emergency Management Agency
FGDC Federal Geographic Data Committee
FSA Forward Sortation Area
GAM geographical analysis machine
GEM geographical explanations machine
GDT Geographic Data Technology
GIF graphics interchange format
GNIS (USGS) Geographic Names Information System
GPS Global Positioning System
GSDI Global Spatial Data Infrastructure
GUI graphical user interface
HTML hypertext markup language
HTTP hypertext transmission protocol
IBM International Business Machines
ICMA International City/Council Management Association
ICT information and communication technology
ID identi®er
IDE integrated development environment
IDW inverse distance weighting
IGN Institut Ge Âographique National
IMS Internet Map Server (as in ESRI's ArcIMS)
IMW The International Map of the World
ISCGM International Steering Committee for Global Mapping
ISO International Standards Organization
ISO TC International Standards Organization Technical
Committee
IT information technology
KE knowledge economy
LAN local area network
LIS land information system
MAPEX MAP EXplorer
MAT minimum aggregate travel
MAUP modi®able areal unit problem
MBR minimum bounding rectangle
MCDM multi-criteria decision-making
MMU minimum mapping unit
MOADB mother of all databases
MrSID Multiresolution Seamless Image Database
MSC (US National Research Council) Mapping Science
Committee
MSS multi-spectral scanner
NAD27 North American Datum of 1927
NAD83 North American Datum of 1983
NASA National Aeronautics and Space Administration
xvii
LI ST OF ACRONYMS
NCDI National Center for Disaster Information (Honduras)
NCGIA National Center for Geographic Information and
Analysis
NGDC National Geospatial Data Clearinghouse
NIMA National Imagery and Mapping Agency
NIMBY not in my back yard
NMD National Mapping Division (former part of USGS)
NMO national mapping organization
NMP (US) National Mapping Program
NSDI National Spatial Data Infrastructure
NTF national transfer format
ODBMS object database management systems
OLE object linking and embedding
OLM object-level metadata
OLS ordinary least squares
OMG Object Management Group
ONC Operational Navigation Chart
ORDBMS object-relational database management systems
PC personal computer
PCC percent correctly classi®ed
PDA personal digital assistant
PLSS Public Land Survey System
PNG portable network graphics
R&D research and development
RDBMS relational database management systems
RMSE root mean squared error
SAP spatially aware professional
SDE Spatial Database Engine (as in ESRI's ArcSDE)
SDTF spatial data transfer standard
SPC State Plane Coordinate
SPOT Syste Áme Probatoire d'Observation de la Terre
SQL structured (or standard) query language
SWOT strengths, weaknesses, opportunities, threats
TIFF tag image ®le format
TIGER Topologically Integrated Geographic Encoding and
Referencing
TIN triangulated irregular network
TLA three letter acronym
TM (Landsat) Thematic Mapper
TSP traveling salesman problem
UCGIS University Consortium for Geographic Information
Science
UML uni®ed modeling language
UNIGIS UNIversity GIS Consortium
UPS Universal Polar Stereographic
URISA Urban and Regional Information Systems Association
USGS United States Geological Survey
UTM Universal Transverse Mercator
VAR value-added reseller
VBA visual BASIC for applications
VGA video graphics array
ViSC Visualization in Scienti®c Computing
VPF vector product format
WAN wide area network
WIMP windows, icons, menus, and pointers
WIPO World Intellectual Property Organization
WWF World Wide Fund (for Nature)
WGS84 World Geodetic System of 1984
Win Windows
WTO World Trade Organization
WWW World Wide Web
XML Extensible Markup Language
xviii
L I S T O F A C R O N Y M S

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