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City and Environment by Christopher G. Boone and Ali Modarres

level nets and chapters 14 through 16 describe adjustment procedures for three traditional types of horizontal surveys: trilateration, triangulation, and traverse. Three-dimensional geodetic network adjustment is covered in chapter 23. Adjustment of GPS (Global Positioning System) observations is the subject of chapter 17, which describes two GPS positioning procedures: pseudoranging and carrierphase measurements. The former is preferred for navigation use because it gives instantaneous point positions, and the latter is the choice for high-precision surveying applications because it yields a higher order of accuracy than the pseudoranging procedure. This chapter focuses on the adjustment of carrier-phase GPS observations. The combination of GPS and terrestrial observations using coordinate transformations from one datum to another is discussed in chapter 24. Most adjustment methods are designed for systematic or random errors. However, measurements often also contain human mistakes (known as blunders or gross errors), and it is desirable to remove blunders from a data set before it is analyzed. Methods for detecting blunders before and after an adjustment are discussed in chapter 21. Performing an adjustment is the beginning of the data analysis process and it is important to evaluate the adjustment results before any sensible analysis can be conducted. The procedures used in assessing results of an adjustment are presented in chapter 25. In surveying and mapping, spatial data often need to be transformed from one coordinate system to another. Chapter 18 covers several well-known and often-used transformations, including the two-dimensional conformal coordinate transformation (also known as the four-parameter similarity transformation), the two-dimensional affine coordinate transformation (the six-parameter transformation), the two-dimensional projective coordinate transformation (the eight-parameter transformation), and the three-dimensional conformal coordinate transformation (the seven-parameter similarity transformation). More rigorous transformation procedures that employ the general least squares method are presented in chapter 22. Two issues common in all adjustment methods are the topics of chapters 19 and 20, with the former describing error ellipse as a representation of estimated errors in the coordinates after completing a least squares adjustment, and the latter discussing constrained adjustments in which certain observations are fixed to a specific value. Many adjustments involve matrix operations that can consume a large amount of computer time and storage, especially for complex problems, and the final chapter of the book discusses computer optimization in applying adjustment methods. Intended for use as a textbook, this volume offers an abundance of examples for the adjustment methods presented and provides additional problems for students at the end of each chapter. The text is a good choice for adjustment computation courses, which are regularly offered in surveying, geodetic science, and civil and environmental engineering departments. This book can also be used as a supplemental text for advanced cartography and GIS/GPS courses offered by a geography department, although the text may prove to be challenging reading for some students who do not have adequate math background. Despite the intention of being used as a textbook, this volume is also a good reference for more advanced readers or professionals who use GPS and GIS for data collection and analysis, such as geographers and urban planners. Although the book is in its fourth edition, there remains room for improvement. More proofreading is needed to eliminate errors: for example, a missing parenthesis in each of equations (6.1), and a missing equals sign in equation (6.9). Rearrangment of some chapters into sections based on themes or topics would allow readers to select and read them as needed.