Geographic Information Systems Demystified For a listing of recent titles in the Artech House Mobile Communications Series, turn to the back of this book Geographic Information Systems Demystified Stephen R Galati artechhouse.com Library of Congress Cataloging-in-Publication Data A catalog record for this book is available from the U.S Library of Congress British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library ISBN-10: 1-58053-533-x ISBN-13: 978-1-58053-533-5 Cover design by Robert Pike © 2006 ARTECH HOUSE, INC 685 Canton Street Norwood, MA 02062 All rights reserved Printed and bound in the United States of America No part of this book may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without permission in writing from the publisher All terms mentioned in this book that are known to be trademarks or service marks have been appropriately capitalized Artech House cannot attest to the accuracy of this information Use of a term in this book should not be regarded as affecting the validity of any trademark or service mark 10 To my wife Janet and my children, Zachary, Nicholas, Sarah, and Jacob Contents xv Preface Acknowledgments xvii Introduction xix Part I: What Is a Geographic Information System? How Does a GIS Work? The Fundamental Flow of Information Geography and Geographic Data Georeferencing Queries: Locations and Attributes Geoprocessing Spatial Analysis 11 Geographic Information 12 Why Use a GIS? 15 Discerning Your Need for GIS 16 vii viii Geographic Information Systems Demystified Common GIS Products and Bi-Products 17 Database Management Systems 19 Quality Assurance, Six Sigma, and GIS 25 Project Visibility and Popularity 26 Benefits, Cost Savings, and Automation 27 The Structure of Geographic Data 29 Raster and Vector Data Structures 29 Vector Feature Geometry 31 Raster Image Structures 34 Topology 35 GIS Attribute Tables and Indices 38 Geospatial Metadata 41 What Is Metadata? 42 Geospatial Metadata and GIS 43 Metadata Schemata, Element Sets, and Syntax 45 Geospatial Metadata Standards 48 Content Standards for Digital Geospatial Metadata Dublin Core Metadata Element Set European CEN Metadata Standard Australian Government Locator Service Metadata Element Set The UK GEMINI Discovery Metadata Standard 50 51 53 Executive Orders 12906 and 13286 55 The National Spatial Data Infrastructure 56 Geospatial Metadata Clearinghouses and Publishing Resources 57 54 54 Contents ix Part II: Geodesy, Earth Models, and Coordinate Systems 59 The Basics of Geodesy and Scale 61 What Is Geodesy? 61 Understanding Map Scale 65 Simple Map Scale Calculations 67 Scale and Accuracy 67 Geographic Data Generalization 69 The Ellipsoid 73 History of the Earth Model 74 Shape of the Earth 75 Mathematical Model of the Earth 77 Typical Earth Shape Calculation 81 WGS84 Constants 81 Reference Ellipsoids 82 The Horizontal Datum 85 What Is a Geodetic Datum? 86 Primary Types of Geodetic Datums 87 Standard Horizontal Datums World Geodetic System 1984 International Terrestrial Reference Frame Geodetic Reference System of 1980 North American Datums of 1927 and 1983 89 89 90 91 92 European Datum 1950 93 Horizontal Datum Transformation Models The Molodensky Datum Transformation Method The Bursa-Wolf Transformation Method 94 95 96 Horizontal Grid Transformation Methods The North American Datum Conversion 99 99 ... a Geographic Information System? From Geographic Data to Geographic Information How Does a GIS Work? In a geographic information system (GIS), geographic data are transformed into geographic information. . .Geographic Information Systems Demystified For a listing of recent titles in the Artech House Mobile Communications Series, turn to the back of this book Geographic Information Systems Demystified. .. milestones in geographic information, while everyday life will continue to embed with GIS applications A Definition of Geographic Information Systems So what is a GIS? A geographic information