Edited by Costa Armenakis and Petros Patias
- Whittles Publishing, Dunbeath, Caithness, UK, 2019.
- 243 x 160 mm, xv + 318 pp, 202 color and black and white illustrations, 31 tables,
3 algorithms, index.
- Hardback, ISBN 978-1-84995-127-2, £85.00. $107.83 Amazon.
UAV-lidar is a hot topic for LIDAR Magazine readers, who have noticed the arrival of sensors from the automotive market. How timely it is, therefore, to have a new textbook that gives structure to the technology and applications of mapping with autonomous vehicles. While its long title underlines the focus on geomatic applications, it reveals little about the types of unmanned vehicle systems (UVSs) it covers, but most of the content concerns UAVs, mainly carrying cameras and sometimes lidar sensors. Indeed, the preface congratulates the geomatics community on its felicitous adoption of UAVs, though it fails to describe the audience at which the book is aimed.
The book is a collection of eight essays. The editors, who are also contributors, are well known. After decades in national mapping in Canada, Costas Armenakis changed horses late in his career and is a professor in geomatics engineering at York University. Petros Patias is professor and director of the Laboratory of Photogrammetry & Remote Sensing, University of Thessaloniki. The book began when the former enjoyed a sabbatical at the seat of learning of the latter. The other contributors are mainly academics, at universities in Canada, Germany, Switzerland and US, but two are in government in Germany and Switzerland and three, in the commercial UAV world in Germany and US.
Armenakis himself authors the introductory chapter, starting with MMSs, UVSs and UAVs. His approach is generic and systematic, but his material on classifying UAVs is awkward as several different schema are breathlessly thrown before the reader. We were guilty of similar taxonomic excesses with analog stereoplotters 50 years ago! On page 9, we hit a major weakness, to which your reviewer will return: a hardcover textbook cannot be up-to-date like a white paper, website or blogsite, but the inclusion of out-of-production UAVs is unfortunate. Notwithstanding this, the overview of the field is welcome. Armenakis turns to the value of UAVs for geomatics, with good sections on sensors and their decreasing SWaP profiles. The UAV part concludes with a section on regulatory issues, again somewhat out of date, and the chapter ends with short, informative sections on ground and marine UVSs. All chapters end with long lists of references.
Chapter 2 is likely to be key for many geomatics readers, covering coordinate systems, transformations, mission planning, image and camera measurements, bundle adjustment, georeferencing, dense image matching, structure from motion, SLAM, orthorectification and registration of point clouds. Encompassing all this in 35 pages is challenging, but there is enough to give a grounding and encourage those interested to look in the many references for more.
Chapter 3, “Unmanned vehicle systems and technologies for sensing and control”, begins with UAVs, their characteristics and their classification—is this repetition of material in chapter 1, or a didactic tool? Certainly there is far more detail here on platforms, including several pages on balloons, cameras and lidar, followed by short sections on multispectral, hyperspectral, acoustic, magnetometer and meteorological sensors. The authors are obviously on home turf in the sections on flight controllers, autopilots and communications. These are probably more important to suppliers than end-users—the book will attract both. Again, the chapter is richly furnished with references, but with reference numbers in square brackets, as opposed to alphabetical listing by author. Chapters 3, 4 and 7 prefer the former; the other chapters, the latter.
Andreas Nüchter (University of Würzburg) is the sole author of chapter 4, on position and orientation of sensors for UVSs. This is primarily about pose estimation for UVSs on the ground. More accustomed to airborne vehicles, your reviewer therefore encountered fresh, enjoyable material here as the equations for robotic motion are developed. The chapter has plentiful equations and algorithms and both Bayes and Kalman filters are introduced. SLAM and calibration are covered, followed by real-world mapping applications. The chapter ends with autonomous navigation and obstacle avoidance.
Most readers of this review will feel on safer ground with chapter 5, “Data acquisition and mapping”. The authors use the term “small-scale” when they really mean “small-area”: with centimeter pixels, you can have a map scale as large as you like! Again there is review material on UAVs, followed by a useful comparison of UAV mapping to other technologies, such as total stations and manned aircraft. This chapter, like the last, is well illustrated with practical examples. Both UAV-photogrammetry and UAV-lidar are covered and there are good discussions of point clouds, orthoimages and accuracy. There is plenty of useful material here and your reviewer would have welcomed even more.
Patias is the sole author of chapter 6, “Applications, case studies and best practices”. He provides summaries of many practical projects, from archaeology and heritage, agriculture and forestry, disaster management and emergency response, mapping and monitoring, transportation, and environment, energy and mining. Each case study is well described and illustrated and ends with a handful of references that Patias accurately calls “credits”. These are over and above the references at the end of the chapter. Some of the 72 figures in the chapter are rather small, but the generous use of color makes most of them work.
The last two chapters are, respectively, “Emerging trends and technologies” and “Outlook—addressing the challenges”. The problem is that, owing to the passing of time, some of the trends and technologies have emerged and some of the challenges have been addressed. Indeed, the way the market has converged, for many applications, on battery-powered multicopters carrying cameras and, in many cases, lidar sensors, was perhaps not foreseen when some of this material was first written. Chapter 7, however, devotes considerable space to system integration—airframe, flight control system, ground control station, data link, fuel, batteries, payload, processor, power systems and software. This is useful and undergirds the value of the book to system and component suppliers as well as users. There is brief discussion of lidar, photogrammetry and other sensors, but much of this material has already been covered. Chapter 8 looks at societal, technological, regulatory and financial challenges. It seems to bring in material from references rather undigested, for example European Community (EC) material on technological issues and both EC and other material on the regulatory environment, which if course is enjoying considerable attention, so is changing too fast for the book to keep up. Incorporating material from commercial and AUVSI reports to provide insight into trends and forecasts is sensible, but the examples chosen were published in 2007 and 2013. It must not be inferred, however, that older material is necessarily incorrect or without value. These two chapters indeed raise important issues.
This is a well produced book, with color on every page, as headings, titles, or graphics, printed on high quality paper. The authors write clearly and their international perspective is appealing. Whittles has been a leading player in geospatial publishing for many years—its location in remote northern Scotland rejuvenates your reviewer’s memories! There are acceptably few typos or glaring errors, except that the two pages of authors’ biographies seem to have been edited very lightly. Also, throughout the book, the terms “GPS” and “GNSS” are used interchangeably, whereas it would have been more pleasing to the eye and consistent to prefer the latter throughout. The spelling of “lidar”, of course, is a topic on its own! There is a glossary of acronyms and initialisms and a four-page index. The book can be enthusiastically recommended, but with a tinge of disappointment: the material needs to be updated: it has very little content and references more recent than 2016. Many of the URLs were last accessed some years ago—did they work the day the book was published? Your reviewer understands that high-end book publishing is far from an instant process, but readers will be distraught that products and technologies they are encountering every day are not mentioned, such as DJI and the leading UAV-lidar integrators. We hope that the second edition provides a thorough update, excises repeated content and combines the last two chapters. Nevertheless, the book sets out a useful framework to understand UVSs in the geomatics world, much of the material is still valuable despite the dated references, and it deserves a place on the shelves of geospatial students, professors, practitioners and suppliers.