Richards Remote Sensing with Imaging Radar

1. Auflage 2009
ISBN: 978-3-642-02020-9
Verlag: Springer
Format: PDF
Kopierschutz: 1 - PDF Watermark

E-Book, Englisch, 361 Seiten

Reihe: Signals and Communication Technology

This book is concerned with remote sensing based on the technology of imaging radar. It assumes no prior knowledge of radar on the part of the reader, commencing with a treatment of the essential concepts of microwave imaging and progressing through to the development of multipolarisation and interferometric radar, modes which underpin contemporary applications of the technology. The use of radar for imaging the earth's surface and its resources is not recent. Aircraft-based microwave systems were operating in the 1960s, ahead of optical systems that image in the visible and infrared regions of the spectrum. Optical remote sensing was given a strong impetus with the launch of the first of the Landsat series of satellites in the mid 1970s. Although the Seasat satellite launched in the same era (1978) carried an imaging radar, it operated only for about 12 months and there were not nearly so many microwave systems as optical platforms in service during the 1980s. As a result, the remote sensing community globally tended to develop strongly around optical imaging until Shuttle missions in the early to mid 1980s and free-flying imaging radar satellites in the early to mid 1990s became available, along with several sophisticated aircraft platforms. Since then, and particularly with the unique capabilities and flexibility of imaging radar, there has been an enormous surge of interest in microwave imaging technology. Unlike optical imaging, understanding the theoretical underpinnings of imaging radar can be challenging, particularly when new to the field.

Autoren/Hrsg.

Richards, John A.

Inhaltsverzeichnis

1;Preface;6
2;TABLE OF CONTENTS;8
3;LIST OF SYMBOLS AND OPERATORS;13
4;Operators and mathematical conventions;19
5;CHAPTER 1 THE IMAGING RADAR SYSTEM;20
5.1;1.1 Why Microwaves?;20
5.2;1.2 Imaging with Microwaves;20
5.3;1.3 Components of an Imaging Radar System;22
5.4;1.4 Assumed Knowledge;24
5.4.1;1.4.1 Complex Numbers;25
5.4.2;1.4.2 Vectors and Matrices;25
5.4.3;1.4.3 Differential Calculus;25
5.5;1.5 Referencing and Footnotes;25
5.6;1.6 A Critical Bibliography;25
5.7;1.7 How this Book is Organised;28
6;CHAPTER 2 THE RADIATION FRAMEWORK;30
6.1;2.1 Energy Sources in Remote Sensing;30
6.2;2.2 Wavelength Ranges used in Remote Sensing;33
6.3;2.3 Total Available Energy;34
6.4;2.4 Energy Available for Microwave Imaging;36
6.5;2.5 Passive Microwave Remote Sensing;38
6.6;2.6 The Atmosphere at Microwave Frequencies;38
6.7;2.7 The Benefits of Radar Remote Sensing;40
6.8;2.8 Looking at the Underlying Electromagnetic Fields;41
6.9;2.9 The Concept of Near and Far Fields;45
6.10;2.10 Polarisation;47
6.11;2.11 The Jones Vector;52
6.12;2.12 Circular Polarisation as a Basis Vector System;55
6.13;2.13 The Stokes Parameters, the Stokes Vector and the Modified Stokes Vector;57
6.14;2.14 Unpolarised and Partially Polarised Radiation;59
6.15;2.15 The Poincaré Sphere;61
6.16;2.16 Transmitting and Receiving Polarised Radiation;63
6.17;2.17 Interference;67
6.18;2.18 The Doppler Effect;68
7;CHAPTER 3 THE TECHNOLOGY OF RADAR IMAGING;72
7.1;PART A: THE SYSTEM;72
7.1.1;3.1 Radar as a Remote Sensing Technology;72
7.1.2;3.2 Range Resolution;74
7.1.3;3.3 Pulse Compression Radar;77
7.1.4;3.4 Resolution in the Along Track Direction;80
7.1.5;3.5 Synthetic Aperture Radar (SAR);80
7.1.6;3.6 The Mathematical Basis for SAR;81
7.1.7;3.7 Swath Width and Bounds on Pulse Repetition Frequency;85
7.1.8;3.8 The Radar Resolution Cell;87
7.1.9;3.9 ScanSAR;87
7.1.10;3.10 Squint and the Spotlight Operating Mode;90
7.2;PART B: THE TARGET;94
7.2.1;3.11 The Radar Equation;94
7.2.2;3.12 Theoretical Expression for Radar Cross Section;96
7.2.3;3.13 The Radar Cross Section in dB;96
7.2.4;3.14 Distributed Targets;97
7.2.5;3.15 The Scattering Coefficient in dB;98
7.2.6;3.16 Polarisation Dependence of the Scattering Coefficient;99
7.2.7;3.17 The Scattering Matrix;100
7.2.8;3.18 Target Vectors;104
7.2.9;3.19 The Covariance and Coherency Matrices;105
7.2.10;3.20 Measuring the Scattering Matrix;108
7.2.11;3.21 Relating the Scattering Matrix to the Stokes Vector;109
7.2.12;3.22 Polarisation Synthesis;111
7.2.13;3.23 Compact Polarimetry;122
7.2.14;3.24 Faraday Rotation;125
8;CHAPTER 4 CORRECTING AND CALIBRATING RADAR IMAGERY;128
8.1;4.1 Sources of Geometric Distortion;128
8.1.1;4.1.1 Near Range Compressional Distortion;128
8.1.2;4.1.2 Layover, Relief Displacement, Foreshortening and Shadowing;130
8.1.3;4.1.3 Slant Range Imagery;132
8.2;4.2 Geometric Correction of Radar Imagery;134
8.2.1;4.2.1 Regions of Low Relief;134
8.2.2;4.2.2 Passive Radar Calibrators;135
8.2.3;4.2.3 Active Radar Calibrators (ARCs);136
8.2.4;4.2.4 Polarimetric Active Radar Calibrators (PARCs);137
8.2.5;4.2.5 Regions of High Relief;137
8.3;4.3 Radiometric Correction of Radar Imagery;139
8.3.1;4.3.1 Speckle;139
8.3.2;4.3.2 Radar Image Products;146
8.3.3;4.3.3 Speckle Filtering;147
8.3.4;4.3.4 Antenna Induced Radiometric Distortion;152
9;CHAPTER 5 SCATTERING FROM EARTH SURFACE FEATURES;154
9.1;5.1 Introduction;154
9.2;5.2 Common Scattering Mechanisms;154
9.3;5.3 Surface Scattering;155
9.3.1;5.3.1 Smooth Surfaces;155
9.3.2;5.3.2 Rough Surfaces;158
9.3.3;5.3.3 Penetration into Surface Materials;167
9.4;5.4 Volume Scattering;172
9.4.1;5.4.1 Modelling Volume Scattering;172
9.4.2;5.4.2 Depolarisation in Volume Scattering;177
9.4.3;5.4.3 Extinction in Volume Scattering;178
9.5;5.5 Scattering from Hard Targets;179
9.5.1;5.5.1 Facet Scattering;180
9.5.2;5.5.2 Dihedral Corner Reflector Behaviour;181
9.5.3;5.5.3 Metallic and Resonant Elements;186
9.5.4;5.5.4 Bragg Scattering;189
9.5.5;5.5.5 The Cardinal Effect;190
9.6;5.6 Composite Scatterers;191
9.7;5.7 Sea Surface Scattering;191
9.8;5.8 Internal (Ocean) Waves;197
9.9;5.9 Sea Ice Scattering;197
10;CHAPTER 6 INTERFEROMETRIC AND TOMOGRAPHIC SAR;200
10.1;6.1 Introduction;200
10.2;6.2 The Importance of Phase;200
10.3;6.3 A Radar Interferometer - InSAR;202
10.4;6.4 Creating the Interferometric Image;204
10.5;6.5 Correcting for Flat Earth Phase Variations;205
10.6;6.6 The Problem with Phase Angle;206
10.7;6.7 Phase Unwrapping;208
10.8;6.8 An Inclined Baseline;209
10.9;6.9 Standard and Ping Pong Modes of Operation;210
10.10;6.10 Types of SAR Interferometry;211
10.11;6.11 The Concept of Critical Baseline;213
10.12;6.12 Decorrelation;215
10.13;6.13 Detecting Topographic Change: Along Track Interferometry;217
10.14;6.14 Polarimetric Interferometric SAR (PolInSAR);221
10.14.1;6.14.1 Fundamental Concepts;221
10.14.2;6.14.2 The T6 Coherency Matrix;225
10.14.3;6.14.3 Maximising Coherence;226
10.14.4;6.14.4 The Plot of Complex Coherence;227
10.15;6.15 Tomographic SAR;228
10.15.1;6.15.1 The Aperture Synthesis Approach;228
10.15.2;6.15.2 The Fourier Transformation Approach to Vertical Resolution;234
10.15.3;6.15.3 Unevenly Spaced Flight Lines;235
10.15.4;6.15.4 Polarisation in Tomography.;236
10.15.5;6.15.5 Polarisation Coherence Tomography;236
10.16;6.16 Range Spectral Filtering and a Re-examination of the Critical Baseline;248
11;CHAPTER 7 BISTATIC SAR;251
11.1;7.1 Introduction;251
11.2;7.2 Generalised Radar Networks;252
11.3;7.3 Analysis of Bistatic Radar;254
11.3.1;7.3.1 The Bistatic Radar Range Equation and the Bistatic Radar Cross Section;254
11.3.2;7.3.2 Bistatic Ground Range Resolution;255
11.3.3;7.3.3 Bistatic Azimuth Resolution;260
11.4;7.4 The General Bistatic Configuration;267
11.5;7.5 Other Bistatic Configurations;274
11.6;7.6 The Need for Transmitter-Receiver Synchronisation;275
11.7;7.7 Using Transmitters of Opportunity;276
11.8;7.8 Geometric Distortion and Shadowing with Bistatic Radar;277
11.9;7.9 Remote Sensing Benefits of Bistatic Radar;278
11.10;7.10 Bistatic Scattering;279
12;CHAPTER 8 RADAR IMAGE INTERPRETATION;282
12.1;8.1 Introduction;282
12.2;8.2 Analytical Complexity;282
12.3;8.3 Visual Interpretation Through an Understanding of Scattering Behaviours;283
12.3.1;8.3.1 The Role of Incidence Angle;284
12.3.2;8.3.2 The Role of Wavelength;285
12.3.3;8.3.3 The Role of Polarisation;286
12.4;8.4 Quantitative Analysis of Radar Image Data for Thematic Mapping;288
12.4.1;8.4.1 Overview of Methods;288
12.4.2;8.4.2 Features Available for Radar Quantitative Analysis;290
12.4.3;8.4.3 Application of Standard Classification Techniques;291
12.4.4;8.4.4 Classification Based on Radar Image Statistics;292
12.4.4.1;8.4.4.1 A Maximum Likelihood Approach;292
12.4.4.2;8.4.4.2 Handling Multi-look Data;295
12.4.4.3;8.4.4.3 Relating the Scattering and Covariance Matrices, and the Stokes ScatteringOperator;296
12.4.4.4;8.4.4.4 Adding Other Dimensionality;297
12.5;8.5 Interpretation Based on Structural Models;298
12.5.1;8.5.1 Interpretation Using Polarisation Phase Difference;298
12.5.2;8.5.2 Interpretation Through Structural Decomposition;300
12.5.2.1;8.5.2.1 Decomposing the Scattering Matrix;301
12.5.2.2;8.5.2.2 Decomposing the Covariance Matrix: the Freeman-Durden Approach;301
12.5.2.3;8.5.2.3 Decomposing the Coherency Matrix: the Cloude-Pottier Approach;305
12.5.2.4;8.5.2.4 Coherency Shape Parameters as Features for PolInSAR Classification;317
12.6;8.6 Interferometric Coherence as a Discriminator;319
12.7;8.7 Some Comparative Classification Results;320
12.8;8.8 Finding Pixel Vertical Detail Using Interferometric Coherence;323
13;CHAPTER 9 PASSIVE MICROWAVE IMAGING;326
13.1;9.1 Introduction;326
13.2;9.2 Radiometric Brightness Temperature;327
13.3;9.3 Relating Microwave Emission to Surface Characteristics;328
13.4;9.4 Emission from Rough Surfaces;331
13.5;9.5 Dependence on Surface Dielectric Constant;332
13.6;9.6 Sea Surface Emission;333
13.7;9.7 Brightness Temperature of Volume Media;335
13.8;9.8 Layered Media: Vegetation over Soil;335
13.9;9.9. Passive Microwave Remote Sensing of the Atmosphere;337
14;APPENDIX A COMPLEX NUMBERS;338
15;APPENDIX B MATRICES;343
15.1;B.1 Matrices and Vectors, Matrix Multiplication;343
15.2;B.2. Indexing and Describing the Elements of a Matrix;344
15.3;B.3 The Kronecker Product;345
15.4;B.4 The Trace of a Matrix;345
15.5;B.5 The Identity Matrix;345
15.6;B.6 The Transpose of a Matrix or a Vector;346
15.7;B.7 The Determinant;347
15.8;B.8 The Matrix Inverse;348
15.9;B.9 Special Matrices;348
15.10;B.10 The Eigenvalues and Eigenvectors of a Matrix;349
15.11;B.11 Diagonalisation of a Matrix;350
15.12;B.12 The Rank of a Matrix;351
16;APPENDIX C SI SYMBOLS AND METRIC PREFIXES;352
17;APPENDIX D IMAGE FORMATION WITH SYNTHETIC APERTURE RADAR;353
17.1;D.1 Summary of the Process;353
17.2;D.2 Range Compression;355
17.3;D.3 Compression in Azimuth;356
17.4;D.4 Look Summing for Speckle Reduction;356
17.5;D.5 Range Curvature;359
17.6;D.6 Side Lobe Suppression;361
18;APPENDIX E BACKSCATTER AND FORWARD SCATTER ALIGNMENT COORDINATE SYSTEMS;364
19;INDEX;367