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Fundamentals of spatial information systems
Book Reviews Riccati equation are presented. From the above survey it follows that the book provides a broad coverage of the polynomial equation approach to control and filtering design problems in linear time-invariant multivariable systems. The material of the book is well selected and well organised. The style is clear, concise and readable. The book is addressed to graduate students specialising in control and filtering problems, and to practising engineers or applied scientists who are interested in new control-system or signal-processing research and development.
Technology of Electrical Measurements, edited by Laszlo SCHNELL; Wiley Series in Measurement Science and Technology; John Wiley and Sons; Chichester, UK; 1993; xv + 409 pp.; £65-00/$104-00: ISBN: 0-471-93435-6 Reviewed by: Dnane MATTERN NYMA Setar at NASA Lewis Research Center, Cleveland, OH, USA This book is one of seven books in the Wile5" series in measurement science and technology. It focuses on electrical measurements, but not on the details of electrical circuitry. The Preface describes the "key concepts" of the book as, "modeling, measurement devices and methods, and measurement error". The book presents the principle of electrical measurements and the limitations inherent in specific techniques. This text has been used to teach a course on measurement technology at a technical university, but practising engineers or scientists will find the presentation of measurement techniques useful in understanding exactly how many instruments actnally work. The book is organized as follows: Chapter 1, by L. Sclmell, discusses the basic concepts of modeling and measurement, and Chapter 2, by I. Zoltan, covers the measurement of current and voltage. Chapter 3. by G. Koranyi. discusses the measurement of power and energy, while Chapter 4, by P. Osvath, examines the measurement of impedances. Chapter 5, by P. Pataki, relates the measurements of time and frequency. Chapter 6, by I. Kollar, covers the tools and methods of signal analysis, and Chapter 7, by L. Schnell, looks briefly at electrical units. The book is very. detailed in describing the various methods of measurement, and the errors and limitations associated with these techniques. Only one error was discovered while reading this manuscript. Chapter 1 starts out by describing how models play a part in shaping the various measurement methods.
1509
The chapter also examines various signal types, measurement errors, basic random signal statistics, and various types of measurement error. Chapters 25 describe just what their titles say they do: current and voltage, power and energy, impedance, and time and frequency. These chapters do a great job in explaining the workings of many measurement devices, from simple DVMs, current sensors and wattmeters to various bridge measurement techuiques and capacitance meters. Two-. three-, fourand five-wire measurements are also discussed. These chapters make this book a good reference in any lab where measurements are not made without understanding the methods behind the instrumentation. In recognition that many instnanents are now built using microprocessors, Chapter 6 describes some of the signal-processing techniques that these instruments use to improve the information presented from the measurements. At 141 pages, Chapter 6 is almost a book in itself, examining basic signal-processing questions like sampling and quantization, and then moving on to tools for analyzing stochastic signals, such as mean, variance, and correlation. An entire section is dedicated to the measurement of spectra, with another section on the measurement of the response of linear systems. This section lists several techniques for perturbing a system to measure the system's frequency response, which this reviewer has used at work. Chapter 7 completes the book. with a discussion of electrical units and their standards. This text does an excellent job of organizing and categorizing electrical measurement techniques. It is difficult for a book of this type to be all-inclusive even when focusing on just electrical measurements. While the signal-processing chapter does mention techniques like cepstnan analysis, the newer timefrequency (wavelet) techniques were noticeably missing, possibly because the most recent reference is 1991. This said. the book is a excellent reference for anyone interested in how electrical measurements are made, or in the assumptions associated with various electrical measurements.
Fundamentals of Spatial Information Systems, by Robert LAURINI and Derek THOMPSON; A.PTC. Series, No. 37; Academic Press; London, UK; 1992: 672 pp.; $49.95; 1SBN: 0-12-438380-7 Reviewed by: Ryan RUDNICKI Southwest Texas State University,, San Marcos, TX, USA In 672 densely written pages liberally sprinkled with tables and clear line drawings, Laurini and Thompson provide an excellent review of spatial informa-
1510
Book Reviews
tion systems from a mathematical and information science perspective. This approach is welcome because it is quite different from the applications perspective taken by most of the other available books on spatial (or geographical) information systems (GIS). Furthermore, because this is a "survey of what is possible now in the domain of organizing and manipulating spatial information", the reader is presented with the view of academicians, not practitioners. The academic perspective helps the user understand the new and powerful technology's methodological and conceptual underpinnings.
lar, will provide the informatician with the necessary background to understand the formidable challenge presented by the processing of spatially-based information. While the authors identify the third kind of reader as students at university who have no background in GIS, experience would suggest that they should have a sound mathematical background, as well as a curiosity about how to deal with geographical data in an information systems context. Most students take a GIS class to learn how the tool can help them in their field, not how the tool works.
In the first half of the book (eight chapters) Laurini and Thompson deal with spatial entities, i.e., geographical features and their representation as points, lines, polygons, and volumes in computer systems. The notions of fractal and Euclidean geometry for storing spatial data in a digital environment, as well as the notion of topology to represent humandeduced relationships when looking at maps, are covered in detail. The representation of earth reality in computers extends to a consideration of the kinds of analytical operations that can be used on spatial data stored in grid (tessellation) as well as vector formats.
The authors describe this as a textbook, and in some ways it is. For example, each chapter ends with a fairly comprehensive bibliography. However this book is really more--a reference book. Too much information is presented within its covers to consign it to the ranks of ordinary textbooks. Furthermore, in a typical textbook, the material is presented in a hierarchical order, enabling students to readily organize the material in. order of importance. The presentation of the subject matter in this book does not follow that pattern, being more encyclopaedic, with one topic presented after another. This book could be used as a text in a course if the instructor provides the organization, and relies on Laurini and Thompson for the details.
Seven of the nine chapters that comprise the book's second half explore the representation of spatial features and related attribute information from a database model perspective. First, the authors detail database models and their suitability for spatial (entity and relationship) data. Just how can earth features and their attributes be handled by hierarchical, network (represented by the CODASYL model), tiat-file, and relational models7 The relational database model holds sway today in spatial information systems, as in most other database applications. Next, the authors examine query" structures for spatial data after the information about places has been assembled into "databases of the relational kind". The exposition covers relational and Peano algebra in one chapter, and then presents algorithms for spatial queries in the next. The book's final two chapters consider multimediaJhypermedia issues in spatial information systems, as well as the objectoriented organization and mampulation of spatial data. This book is oriented toward three kinds of reader: first, those who have worked with a GIS and wish to gain an understanding of the technology's fundamental concepts and methods. Second, this book is for the computer information specialists (including control engineers) who are interested in learning how spatial data are being incorporated into existing database management systems. These information system engineers tend to underestimate the complexity of spatial data. This book's first half, in particu-
There is little to be critical of in this pioneering text. The book's editing is excellent, with typographical errors almost non-existent. One has to look very closely to find a misspelled word or see that the page numbers given for two of the table of contents headings are incorrect (p.392 instead of p.391). The book has one minor idiosyncrasy that does not detract from its utility. Throughout the book are terms in bold-face type that the authors consider important. These do not exist in a glossary, nor do a number of them appear in the index. A reader might overlook the lack of a glossary because the terms are adequately explained in the body of the text. Their absence from the index is more problematical. If an instructor wishes to assign a set of those bolded, key terms, students cannot easily locate the words in the book without much page flipping. The authors see a bright future for spatial information systems. At present, these collections of hardware and software serve as valuable aids, leading to a better understanding of the dynamic spatial world. In the future the technology may well be a resource that will change the way in which some academic disciplines are taught. Spatial information systems represent a way of looking at problems; they therefore offer users the potential of a different way of thinking about the world. Because of this, scientists and engineers interested in developing spatial information system products would benefit from a thoughtful perusal of the Laurini and Thompson book.
Technology of Electrical Measurements, edited by Laszlo SCHNELL; Wiley Series in Measurement Science and Technology; John Wiley and Sons; Chichester, UK; 1993; xv + 409 pp.; £65-00/$104-00: ISBN: 0-471-93435-6 Reviewed by: Dnane MATTERN NYMA Setar at NASA Lewis Research Center, Cleveland, OH, USA This book is one of seven books in the Wile5" series in measurement science and technology. It focuses on electrical measurements, but not on the details of electrical circuitry. The Preface describes the "key concepts" of the book as, "modeling, measurement devices and methods, and measurement error". The book presents the principle of electrical measurements and the limitations inherent in specific techniques. This text has been used to teach a course on measurement technology at a technical university, but practising engineers or scientists will find the presentation of measurement techniques useful in understanding exactly how many instruments actnally work. The book is organized as follows: Chapter 1, by L. Sclmell, discusses the basic concepts of modeling and measurement, and Chapter 2, by I. Zoltan, covers the measurement of current and voltage. Chapter 3. by G. Koranyi. discusses the measurement of power and energy, while Chapter 4, by P. Osvath, examines the measurement of impedances. Chapter 5, by P. Pataki, relates the measurements of time and frequency. Chapter 6, by I. Kollar, covers the tools and methods of signal analysis, and Chapter 7, by L. Schnell, looks briefly at electrical units. The book is very. detailed in describing the various methods of measurement, and the errors and limitations associated with these techniques. Only one error was discovered while reading this manuscript. Chapter 1 starts out by describing how models play a part in shaping the various measurement methods.
1509
The chapter also examines various signal types, measurement errors, basic random signal statistics, and various types of measurement error. Chapters 25 describe just what their titles say they do: current and voltage, power and energy, impedance, and time and frequency. These chapters do a great job in explaining the workings of many measurement devices, from simple DVMs, current sensors and wattmeters to various bridge measurement techuiques and capacitance meters. Two-. three-, fourand five-wire measurements are also discussed. These chapters make this book a good reference in any lab where measurements are not made without understanding the methods behind the instrumentation. In recognition that many instnanents are now built using microprocessors, Chapter 6 describes some of the signal-processing techniques that these instruments use to improve the information presented from the measurements. At 141 pages, Chapter 6 is almost a book in itself, examining basic signal-processing questions like sampling and quantization, and then moving on to tools for analyzing stochastic signals, such as mean, variance, and correlation. An entire section is dedicated to the measurement of spectra, with another section on the measurement of the response of linear systems. This section lists several techniques for perturbing a system to measure the system's frequency response, which this reviewer has used at work. Chapter 7 completes the book. with a discussion of electrical units and their standards. This text does an excellent job of organizing and categorizing electrical measurement techniques. It is difficult for a book of this type to be all-inclusive even when focusing on just electrical measurements. While the signal-processing chapter does mention techniques like cepstnan analysis, the newer timefrequency (wavelet) techniques were noticeably missing, possibly because the most recent reference is 1991. This said. the book is a excellent reference for anyone interested in how electrical measurements are made, or in the assumptions associated with various electrical measurements.
Fundamentals of Spatial Information Systems, by Robert LAURINI and Derek THOMPSON; A.PTC. Series, No. 37; Academic Press; London, UK; 1992: 672 pp.; $49.95; 1SBN: 0-12-438380-7 Reviewed by: Ryan RUDNICKI Southwest Texas State University,, San Marcos, TX, USA In 672 densely written pages liberally sprinkled with tables and clear line drawings, Laurini and Thompson provide an excellent review of spatial informa-
1510
Book Reviews
tion systems from a mathematical and information science perspective. This approach is welcome because it is quite different from the applications perspective taken by most of the other available books on spatial (or geographical) information systems (GIS). Furthermore, because this is a "survey of what is possible now in the domain of organizing and manipulating spatial information", the reader is presented with the view of academicians, not practitioners. The academic perspective helps the user understand the new and powerful technology's methodological and conceptual underpinnings.
lar, will provide the informatician with the necessary background to understand the formidable challenge presented by the processing of spatially-based information. While the authors identify the third kind of reader as students at university who have no background in GIS, experience would suggest that they should have a sound mathematical background, as well as a curiosity about how to deal with geographical data in an information systems context. Most students take a GIS class to learn how the tool can help them in their field, not how the tool works.
In the first half of the book (eight chapters) Laurini and Thompson deal with spatial entities, i.e., geographical features and their representation as points, lines, polygons, and volumes in computer systems. The notions of fractal and Euclidean geometry for storing spatial data in a digital environment, as well as the notion of topology to represent humandeduced relationships when looking at maps, are covered in detail. The representation of earth reality in computers extends to a consideration of the kinds of analytical operations that can be used on spatial data stored in grid (tessellation) as well as vector formats.
The authors describe this as a textbook, and in some ways it is. For example, each chapter ends with a fairly comprehensive bibliography. However this book is really more--a reference book. Too much information is presented within its covers to consign it to the ranks of ordinary textbooks. Furthermore, in a typical textbook, the material is presented in a hierarchical order, enabling students to readily organize the material in. order of importance. The presentation of the subject matter in this book does not follow that pattern, being more encyclopaedic, with one topic presented after another. This book could be used as a text in a course if the instructor provides the organization, and relies on Laurini and Thompson for the details.
Seven of the nine chapters that comprise the book's second half explore the representation of spatial features and related attribute information from a database model perspective. First, the authors detail database models and their suitability for spatial (entity and relationship) data. Just how can earth features and their attributes be handled by hierarchical, network (represented by the CODASYL model), tiat-file, and relational models7 The relational database model holds sway today in spatial information systems, as in most other database applications. Next, the authors examine query" structures for spatial data after the information about places has been assembled into "databases of the relational kind". The exposition covers relational and Peano algebra in one chapter, and then presents algorithms for spatial queries in the next. The book's final two chapters consider multimediaJhypermedia issues in spatial information systems, as well as the objectoriented organization and mampulation of spatial data. This book is oriented toward three kinds of reader: first, those who have worked with a GIS and wish to gain an understanding of the technology's fundamental concepts and methods. Second, this book is for the computer information specialists (including control engineers) who are interested in learning how spatial data are being incorporated into existing database management systems. These information system engineers tend to underestimate the complexity of spatial data. This book's first half, in particu-
There is little to be critical of in this pioneering text. The book's editing is excellent, with typographical errors almost non-existent. One has to look very closely to find a misspelled word or see that the page numbers given for two of the table of contents headings are incorrect (p.392 instead of p.391). The book has one minor idiosyncrasy that does not detract from its utility. Throughout the book are terms in bold-face type that the authors consider important. These do not exist in a glossary, nor do a number of them appear in the index. A reader might overlook the lack of a glossary because the terms are adequately explained in the body of the text. Their absence from the index is more problematical. If an instructor wishes to assign a set of those bolded, key terms, students cannot easily locate the words in the book without much page flipping. The authors see a bright future for spatial information systems. At present, these collections of hardware and software serve as valuable aids, leading to a better understanding of the dynamic spatial world. In the future the technology may well be a resource that will change the way in which some academic disciplines are taught. Spatial information systems represent a way of looking at problems; they therefore offer users the potential of a different way of thinking about the world. Because of this, scientists and engineers interested in developing spatial information system products would benefit from a thoughtful perusal of the Laurini and Thompson book.