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Spie Press Book

Getting Started with UAV Imaging Systems: A Radiometric Guide
Author(s): Barbara G. Grant
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Book Description

Getting Started with UAV Imaging Systems: A Radiometric Guide provides the tools technologists need to begin designing or analyzing the data product of a UAV imager. Covering the basics of target signatures, radiometric propagation, electro-optical systems, UAV platforms, and image quality, it is replete with examples that promote immediate application of the concepts. Reference materials at the end of each chapter, including many links to current systems and platforms, offer further guidance for readers. Engineers and scientists who specify instrument requirements; design, build, or test hardware; or analyze images for commercial, scientific, and military applications will find the book a useful addition to their working library.

This text is a positive contribution to the ‘Getting Started’ literature in UAV imaging. The math and concepts are not simple but are presented and explained in a way that is accessible to a broad audience.”
—from a book review by Melissa J. Rura, Ph.D published in Photogrammatric Engineering & Remote Sensing 83(3), 176 (2017) [doi: 10.14358/PERS.83.3.175]

Book Details

Date Published: 20 July 2016
Pages: 162
ISBN: 9781510601833
Volume: PM270

Table of Contents
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Table of Contents

List of Acronyms and Abbreviations

1 Introduction
1.1 UAV Imaging: A Disruptive Innovation
1.2 Components of a UAV System
1.3 Size, Weight, Power, and Platform
1.4 Terminology and Acronyms

2 Radiometry of Targets: Emission and Reflection
2.1 Introduction
2.2 The Electromagnetic Spectrum
2.3 Emission and Reflection within Spectral Regions
      2.3.1 Overview
      2.3.2 Emission
      2.3.3 Reflection

3 Radiometric Propagation Basics
3.1 Plane Angle and Instantaneous Field of View
3.2 Solid Angle and Projected Solid Angle
3.3 Radiometric Terms and Their Units
      3.3.1 Radiance
      3.3.2 Irradiance
      3.3.3 Radiant exitance
      3.3.4 Radiant intensity
      3.3.5 Summary of radiometric terms and units
      3.3.6 Summary of the terms, in photons
      3.3.7 Imaging spectroscopy and wavenumber
3.4 Relationships Important to Propagation Calculations
      3.4.1 The inverse square law of irradiance
      3.4.2 Intensity and radiance relationship
      3.4.3 Conclusion

4 Imaging System Basics
4.1 Introduction
4.2 The Camera Equation and Image Plane Irradiance
4.3 Terms and Definitions Relating to Image Acquisition Geometry
      4.3.1 Elevation angle
      4.3.2 Sensor relative elevation angle
      4.3.3 Sensor relative azimuth angle
      4.3.4 Horizontal and vertical fields of view
      4.3.5 Ground sample distance
      4.3.6 Slant range
4.4 General Description of Optical Systems for UAV Imaging
4.5 Spectral Imaging
4.6 Calculating the Signal from the Focal Plane: A Multispectral-Channel Example
4.7 Noise Equivalent Power
4.8 Noise Equivalent Radiance
4.9 Noise Equivalent Irradiance
4.10 Noise Equivalent Reflectance Difference
4.11 Modulation Transfer Function

5 Platforms, Sensors, and Applications
5.1 Introduction
5.2 Large Military Platforms
5.3 Small UAV Platforms
      5.3.1 SWaP-C and sUAS
      5.3.2 UAV swarm: the smallest platform/sensor subtype
      5.3.3 Factors that influence platform selection
      5.3.4 Pointing the payload
5.4 Platform and Application Examples
      5.4.1 Distinguishing between two objects at UAV altitude
      5.4.2 Near-infrared and SWIR imaging comparison
      5.4.3 "Day/night" imager and covert illumination
      5.4.4 Uncooled thermal microbolometer
5.5 Thermal Contrast
5.6 Noise Equivalent Temperature Difference
      5.6.1 NETD expression for energy units
      5.6.2 NETD in terms of photons
5.7 Minimum Resolvable Temperature Difference

6 The Image Data Product and Quality Metrics
6.1 Introduction
6.2 Imagery Authentication
6.3 Metadata
6.4 Video, Motion Imagery, and Full Motion Video
6.5 Video Scan Types
6.6 Definition in Lines per Frame
6.7 Image Quality Scales
      6.7.1 Introduction
      6.7.2 Motion imagery: video NIIRS
      6.7.3 Still imagery: NIIRS and IIRS
      6.7.4 Predicting NIIRS: the general image quality equation
6.8 Probability of Discrimination
      6.8.1 Johnson criteria and target transfer probability functions
      6.8.2 Probability calculations
      6.8.3 Comparison with the NIIRS criteria
6.9 Atmospheric Correction
      6.9.1 Introduction
      6.9.2 Atmospheric windows and narrow bands

7 Detectors for UAV Imaging Systems
7.1 Introduction
7.2 Photon Detectors
7.3 CCD and CMOS
      7.3.1 CCD basics
      7.3.2 Color CCDs
      7.3.3 CMOS basics
7.4 Thermal Detectors
      7.4.1 Thermal detection basics
      7.4.2 The microbolometer
7.5 Detector Noise Sources
      7.5.1 Johnson noise
      7.5.2 Shot noise
      7.5.3 Generation-recombination noise
      7.5.4 Temperature fluctuation noise
      7.5.5 1/f noise
      7.5.6 Photon noise
      7.5.7 Quantization noise
      7.5.8 Additional detector noises
      7.5.9 Noises in arrays

8 Conclusion

Appendix A SI Base Units and Derived Quantities

Appendix B Concise Notation, Uncertainty Reporting, and CODATA 2014 Physical Constants
B.1 Reporting Uncertainty
B.2 Pending Changes in Values of "Constants"

Appendix C Drones and the Law
C.1 Commercial Use of Drones and FAA Regulations
C.2 Security, Privacy, and Law Enforcement Issues

Appendix D The Need for Standards in UAV Imagery Analysis
D.1 Connecting the Dots
D.2 Marking the Scorecard



Unmanned aerial vehicles—UAVs—will revolutionize the ways in which we conduct business, perform research, enforce the law, manage natural resources, educate students, and execute many other tasks. While advances in computing technology enhance cloud storage and maximize data exploitation, the UAV imaging sensor remains the key component driving system performance and market growth.

This book is an effort to examine UAV imaging systems in light of their platform and applications contexts. As such, it is replete with examples that allow readers to witness concepts immediately applied to challenges they face. Engineers and scientists who specify instrument requirements; design, build, or test hardware; or analyze images for commercial, scientific, and military applications will find the book a useful addition to their working library.

Chapter 1 introduces UAV imagers and discusses their disruptive potential. Chapters 2, 3, and 4 introduce target characteristics, radiometric propagation, and imaging system basics including figures of merit. Chapter 5 expands the study by discussing platforms and, thereafter, focusing primarily on problems in the thermal infrared spectral region. Chapter 6 examines key issues in evaluating the image data product, including video and still imagery rating scales. Chapter 7 surveys optical radiation detectors for those who require an introduction.

I am grateful to many individuals and organizations who directly helped in the creation of this work. Kenneth N. Schindler, audio and video engineer at Dolby Labs, San Francisco, CA, critiqued and improved the video narrative in Chapter 6. Chris Van Veen of Headwall Photonics, Fitchburg, MA, supplied images of a hyperspectral device aboard its platform and the resulting imagery. General Atomics of Poway, CA, allowed me to use its image of a Predator UAV, and Xenics Infrared Solutions, Leuven, Belgium, provided a thermal infrared image.

I remain grateful to the excellent staff at SPIE Press, including my editor, Scott McNeill, who offered many helpful comments, and Press Manager Tim Lamkins. It was a pleasure for me to work with both of them again. Reviewers William L. Wolfe (I still use The Infrared Handbook), Professor Emeritus of Optical Sciences at the University of Arizona, and Cornelius J. Willers, Airbus Defense and Space, Republic of South Africa, provided valuable critique and many helpful suggestions; any errors or omissions remain mine, alone. As in my prior publications, I give great credit to three professors emeriti from the College of Optical Sciences—Phil Slater, the late Jim Palmer, and Eustace Dereniak—who have significantly influenced my life and work.

I am grateful to family and friends who supported and prayed with me during a difficult season. I dedicate this book to the memory of my mother, Esther, whose tenacity in the face of adversity continues to provide a positive example.

Barbara G. Grant
Cupertino, California
April 2016

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