ItemAirborne Laser Hydrography II(2019)This book was written to document and share our updated knowledge of airborne lidar hydrography gained since Gary C. Guenther wrote the original seminal book Airborne Laser Hydrography - System Design and Performance Factors over 30 years ago. Like the first book, commonly referred to as the Blue Book, this Blue Book II updates the history, theory, and design challenges of bathymetric lidar. However, with over 30 years of advancements and most importantly with thousands of hours of operational experience from different international teams and system, Blue Book II provides knowledge gained through decades of operational experience over a wide range of applications and environmental conditions. Mr. Guenther’s Blue Book laid the foundation that over 16 authors from a half dozen countries update in Blue Book II. ItemChapter 7: Applications, Ancillary Systems, and FusionWozencraft, Jennifer; Eisemann, Eve; Reif, Molly; Dunkin, Lauren (2019)The number of applications for ALB data has grown exponentially since the first systems became operational in the late 1980's and early 1990's. In those early days, the primary application was nautical charting. Since then, as more systems were developed and fielded, and users gained access to the unique datasets provided by these systems, uses have expanded into a wide variety of coastal engineering and coastal zone management applications. Many of these applications take advantage of the regional-scale, reoccurring elevation and depth data provided by ALB systems. Others utilize semi-automated and automated techniques to extract features from the lidar elevation data, or from lidar waveforms. Still others combine ALB data with ancillary aerial photography or hyperspectral imagery using data fusion at various levels in the processing change to create new data products that further extend the utility of these datasets. This chapter briefly highlights a number of applications for ALB data that have evolved over the past 25 year of ALB operations: nautical charting, navigation project monitoring, regional sediment management, post-storm response, geomorphological feature extraction, and environmental mapping. It is not exhaustive, but gives an overview of the breadth of operational applications for ALB. The chapter closes with a look into future applications. ItemChapter 6: Performance EvaluationPe'eri, Shackak; Parrish, Christopher; Johnson, Nicholas; Macon, Christopher; White, Stephen (2019)In order to be able to provide a clean georeferenced point cloud for analysis and production, it is important to conduct a performance evaluation of an ALB system prior to conducting a survey. The term "performance evaluation" here refers to the tests that accompany the delivery of the ALB system from the manufacturer to the service provider, and the approaches presented are based on the experience of U.S. government agencies and service providers. Specifics of the evaluation can vary substantially based on user requirements and available resources. In this chapter, a general overview of common procedures is provided regarding the approaches used for an ALB system performance evaluation. Some of the approaches reviewed below have been used with topographic lidar systems and for acoustic ship-borne transducers (namely, multibeam echosounders), but have not yet been tested with ALB systems. Although the manufacturer may have already conducted some calibration tests when a new system was first delivered to the surveyor, it is important to repeat the procedures again using the service provider's aircraft. The six parameters that are used to evaluate the systems are: system health, noise evaluation, coverage evaluation, geometric calibration, accuracy evaluation and image/intensity quality evaluation. In addition to acceptance, these parameters can be used as a baseline for future evaluation on the system, namely degradation or changes in the ALB system over time. ItemChapter 5: Basic Concepts in Data ProcessingFeygels, Viktor; Kopilevich, Yuri; Kim, Minsu; Wang, Chi-Kuei (2019)This chapter details the various data processing steps used to retrieve useful data from the lidar waveform (other than depth of an individual pulse). The introductory section describes the sequence of coordinate transformations and translations required to produce a georeferenced lidar point cloud. The next section presents a general approach to the inverse problem of lidar waveform processing with the goal of retrieving inherent optical properties (IOPs) of seawater, followed by a sections discussing retrieval of the water diffuse attenuation coefficient and the estimate of bottom reflectance at the lidar wavelength. The final section is a discussion of the effects of forward scattering on the shape and position of the surface reflection and bottom pulse. ItemChapter 4: Basic Concepts and System DesignFeygels, Viktor; Kopilevich, Yuri; Kim, Minsu; LaRocque, Paul; Pe'eri, Shachak; Philpot, William (2019)All airborne lidar bathymeter (ALB) systems locate the bottom of a water body by tracking the progression of a short light pulse from its initial contact with the water surface through its interaction with the bottom. The detected signal is the light backscattered by the water column, or reflected by the water surface or the bottom as represented by the waveform - a time-series of the return intensity. All systems share a common set of design elements, face a similar set of design constraints, and ultimately rely on an analysis of a series of detected waveforms to produce a map of the bathymetry. The characteristics of the waveform depend both on the environmental optical properties - especially the water inherent optical properties (IOPs, see Chap. 2) - and on system design. A major purpose of this chapter is to present a mathematical description of the process, incorporating realistic representations of the system elements and pulse propagation geometry. Using a special implementation of the small-angle approximation, a closed form expression for the waveform is presented. This solution is then used to explore contributions to the observed waveform following adjustments in ALB system design and to examine implications of the model for calibration. The chapter closes with consideration of eye-safety requirements and a discussion of the optimization and technical constraints and tradeoffs on system design. ItemChapter 3: Environmental Optical PropertiesPe'eri, Shachak; Feygels, Viktor; Tingaker, Torbjorn; Kopilevich, Yuri; Kim, Minsu; Philpot, William; Wang, Chi-Kuei (2019)When the lidar pulse is transmitted out of the ALB system, it interacts with various environmental regions from the time of transmission until the pulse is reflected from the seafloor and received back at the ALB detector. Propagation of the lidar pulse, the change in its shape and distribution, and the light returned to the detector all depend critically on the inherent optical properties (IOPs) of the atmosphere, water surface, water column and bottom. The more descriptive apparent optical properties (AOPs) are also useful for characterizing the limits of penetration of the lidar in terms of perceived water quality. In this chapter, the contributions of each of the main environmental regions and the key optical properties associated with the regions are defined. Optical concepts are briefly described here to explain the changes that a transmitted laser pulse undergoes passing through the environmental regions. These concepts will be used throughout the following chapters. ItemChapter 2: HistoryWozencraft, Jennifer; LaRocque, Paul; Penley, Mark; Pfennigbauer, Martin (2019)The early years of laser hydrography have been traced by Guenther (1985). His review tracks the development of laser hydrography, now more commonly known as Airborne Laser Bathymetry (ALB), from the earliest theoretical and experimental efforts in the mid-1960's dealing with in-water lasers and the first demonstration systems capable of detecting bottom returns through the development of the first operational systems. The history was later extended to 1990 in a paper by Sizgoric, Banic and Guenther (1992). Guenther further detailed this history and provided descriptions of operational systems in the Airborne Lidar Bathymetry chapter of The DEM User's Manual (Guenther 2001), which he later updated in the 2nd Edition of the User's Manual (Guenther 2007). This chapter summarizes and updates these reference documents.