Author: Jong-Sen Lee
Publisher: CRC Press
ISBN: 1420054988
Category : Technology & Engineering
Languages : en
Pages : 432
Book Description
The recent launches of three fully polarimetric synthetic aperture radar (PolSAR) satellites have shown that polarimetric radar imaging can provide abundant data on the Earth’s environment, such as biomass and forest height estimation, snow cover mapping, glacier monitoring, and damage assessment. Written by two of the most recognized leaders in this field, Polarimetric Radar Imaging: From Basics to Applications presents polarimetric radar imaging and processing techniques and shows how to develop remote sensing applications using PolSAR imaging radar. The book provides a substantial and balanced introduction to the basic theory and advanced concepts of polarimetric scattering mechanisms, speckle statistics and speckle filtering, polarimetric information analysis and extraction techniques, and applications typical to radar polarimetric remote sensing. It explains the importance of wave polarization theory and the speckle phenomenon in the information retrieval problem of microwave imaging and inverse scattering. The authors demonstrate how to devise intelligent information extraction algorithms for remote sensing applications. They also describe more advanced polarimetric analysis techniques for polarimetric target decompositions, polarization orientation effects, polarimetric scattering modeling, speckle filtering, terrain and forest classification, manmade target analysis, and PolSAR interferometry. With sample PolSAR data sets and software available for download, this self-contained, hands-on book encourages you to analyze space-borne and airborne PolSAR and polarimetric interferometric SAR (Pol-InSAR) data and then develop applications using this data.
Polarimetric Radar Imaging
Author: Jong-Sen Lee
Publisher: CRC Press
ISBN: 1420054988
Category : Technology & Engineering
Languages : en
Pages : 432
Book Description
The recent launches of three fully polarimetric synthetic aperture radar (PolSAR) satellites have shown that polarimetric radar imaging can provide abundant data on the Earth’s environment, such as biomass and forest height estimation, snow cover mapping, glacier monitoring, and damage assessment. Written by two of the most recognized leaders in this field, Polarimetric Radar Imaging: From Basics to Applications presents polarimetric radar imaging and processing techniques and shows how to develop remote sensing applications using PolSAR imaging radar. The book provides a substantial and balanced introduction to the basic theory and advanced concepts of polarimetric scattering mechanisms, speckle statistics and speckle filtering, polarimetric information analysis and extraction techniques, and applications typical to radar polarimetric remote sensing. It explains the importance of wave polarization theory and the speckle phenomenon in the information retrieval problem of microwave imaging and inverse scattering. The authors demonstrate how to devise intelligent information extraction algorithms for remote sensing applications. They also describe more advanced polarimetric analysis techniques for polarimetric target decompositions, polarization orientation effects, polarimetric scattering modeling, speckle filtering, terrain and forest classification, manmade target analysis, and PolSAR interferometry. With sample PolSAR data sets and software available for download, this self-contained, hands-on book encourages you to analyze space-borne and airborne PolSAR and polarimetric interferometric SAR (Pol-InSAR) data and then develop applications using this data.
Publisher: CRC Press
ISBN: 1420054988
Category : Technology & Engineering
Languages : en
Pages : 432
Book Description
The recent launches of three fully polarimetric synthetic aperture radar (PolSAR) satellites have shown that polarimetric radar imaging can provide abundant data on the Earth’s environment, such as biomass and forest height estimation, snow cover mapping, glacier monitoring, and damage assessment. Written by two of the most recognized leaders in this field, Polarimetric Radar Imaging: From Basics to Applications presents polarimetric radar imaging and processing techniques and shows how to develop remote sensing applications using PolSAR imaging radar. The book provides a substantial and balanced introduction to the basic theory and advanced concepts of polarimetric scattering mechanisms, speckle statistics and speckle filtering, polarimetric information analysis and extraction techniques, and applications typical to radar polarimetric remote sensing. It explains the importance of wave polarization theory and the speckle phenomenon in the information retrieval problem of microwave imaging and inverse scattering. The authors demonstrate how to devise intelligent information extraction algorithms for remote sensing applications. They also describe more advanced polarimetric analysis techniques for polarimetric target decompositions, polarization orientation effects, polarimetric scattering modeling, speckle filtering, terrain and forest classification, manmade target analysis, and PolSAR interferometry. With sample PolSAR data sets and software available for download, this self-contained, hands-on book encourages you to analyze space-borne and airborne PolSAR and polarimetric interferometric SAR (Pol-InSAR) data and then develop applications using this data.
Polarimetric SAR Imaging
Author: Yoshio Yamaguchi
Publisher: CRC Press
ISBN: 1000075702
Category : Technology & Engineering
Languages : en
Pages : 330
Book Description
Radar polarimetry has been highly sought after for its use in the precise monitoring of Earth's surface. Polarimetric SAR Imaging explains the basic concepts of polarimetry and its diverse applications including: deforestation, tree classification, landslide detection, tsunamis, volcano eruptions and ash distribution, snow accumulation, rice field monitoring, urban area exploration, ship detection, among other applications. The explanations use actual data sets taken by Advanced Land Observing Satellite (ALOS and ALOS2). With the increasing problems presented by climate change, there is a growing need for detailed earth observation using polarimetric data. As the treatment of vector nature of radar waves is complex, there is a gap between the theory and the application. Polarimetric SAR Imaging: Theory and Applications addresses and fills this gap. Features: Provides cutting-edge polarimetric applications for earth observation with full color images. Includes detailed descriptions of theory, equations, expansions, and flowcharts, and numerous real examples. Explains concepts, data analysis, and applications in simple and clear language aimed at an intuitive comprehension. Provides specific and unique examples of PolSAR images derived from actual space and airborne systems (ALOS/ALOS2, PiSAR-x/L) Covers the wide range of the radar polarimetry, especially the decomposition of the polarimetry data, an original method developed by the author using the Japanese polarimetric SAR data Illustrated in full color using images generated by polarimetric techniques, this book is easy to understand and use for both student and expert, and is an excellent resource both in the classroom and in the field.
Publisher: CRC Press
ISBN: 1000075702
Category : Technology & Engineering
Languages : en
Pages : 330
Book Description
Radar polarimetry has been highly sought after for its use in the precise monitoring of Earth's surface. Polarimetric SAR Imaging explains the basic concepts of polarimetry and its diverse applications including: deforestation, tree classification, landslide detection, tsunamis, volcano eruptions and ash distribution, snow accumulation, rice field monitoring, urban area exploration, ship detection, among other applications. The explanations use actual data sets taken by Advanced Land Observing Satellite (ALOS and ALOS2). With the increasing problems presented by climate change, there is a growing need for detailed earth observation using polarimetric data. As the treatment of vector nature of radar waves is complex, there is a gap between the theory and the application. Polarimetric SAR Imaging: Theory and Applications addresses and fills this gap. Features: Provides cutting-edge polarimetric applications for earth observation with full color images. Includes detailed descriptions of theory, equations, expansions, and flowcharts, and numerous real examples. Explains concepts, data analysis, and applications in simple and clear language aimed at an intuitive comprehension. Provides specific and unique examples of PolSAR images derived from actual space and airborne systems (ALOS/ALOS2, PiSAR-x/L) Covers the wide range of the radar polarimetry, especially the decomposition of the polarimetry data, an original method developed by the author using the Japanese polarimetric SAR data Illustrated in full color using images generated by polarimetric techniques, this book is easy to understand and use for both student and expert, and is an excellent resource both in the classroom and in the field.
Synthetic Aperture Radar Polarimetry
Author: Jakob J. van Zyl
Publisher: John Wiley & Sons
ISBN: 1118116097
Category : Technology & Engineering
Languages : en
Pages : 285
Book Description
This book describes the application of polarimetric synthetic aperture radar to earth remote sensing based on research at the NASA Jet Propulsion Laboratory (JPL). This book synthesizes all current research to provide practical information for both the newcomer and the expert in radar polarimetry. The text offers a concise description of the mathematical fundamentals illustrated with many examples using SAR data, with a main focus on remote sensing of the earth. The book begins with basics of synthetic aperture radar to provide the basis for understanding how polarimetric SAR images are formed and gives an introduction to the fundamentals of radar polarimetry. It goes on to discuss more advanced polarimetric concepts that allow one to infer more information about the terrain being imaged. In order to analyze data quantitatively, the signals must be calibrated carefully, which the book addresses in a chapter summarizing the basic calibration algorithms. The book concludes with examples of applying polarimetric analysis to scattering from rough surfaces, to infer soil moisture from radar signals.
Publisher: John Wiley & Sons
ISBN: 1118116097
Category : Technology & Engineering
Languages : en
Pages : 285
Book Description
This book describes the application of polarimetric synthetic aperture radar to earth remote sensing based on research at the NASA Jet Propulsion Laboratory (JPL). This book synthesizes all current research to provide practical information for both the newcomer and the expert in radar polarimetry. The text offers a concise description of the mathematical fundamentals illustrated with many examples using SAR data, with a main focus on remote sensing of the earth. The book begins with basics of synthetic aperture radar to provide the basis for understanding how polarimetric SAR images are formed and gives an introduction to the fundamentals of radar polarimetry. It goes on to discuss more advanced polarimetric concepts that allow one to infer more information about the terrain being imaged. In order to analyze data quantitatively, the signals must be calibrated carefully, which the book addresses in a chapter summarizing the basic calibration algorithms. The book concludes with examples of applying polarimetric analysis to scattering from rough surfaces, to infer soil moisture from radar signals.
Polarimetric Synthetic Aperture Radar
Author: Irena Hajnsek
Publisher: Springer Nature
ISBN: 3030565041
Category : Technology & Engineering
Languages : en
Pages : 304
Book Description
This open access book focuses on the practical application of electromagnetic polarimetry principles in Earth remote sensing with an educational purpose. In the last decade, the operations from fully polarimetric synthetic aperture radar such as the Japanese ALOS/PalSAR, the Canadian Radarsat-2 and the German TerraSAR-X and their easy data access for scientific use have developed further the research and data applications at L,C and X band. As a consequence, the wider distribution of polarimetric data sets across the remote sensing community boosted activity and development in polarimetric SAR applications, also in view of future missions. Numerous experiments with real data from spaceborne platforms are shown, with the aim of giving an up-to-date and complete treatment of the unique benefits of fully polarimetric synthetic aperture radar data in five different domains: forest, agriculture, cryosphere, urban and oceans.
Publisher: Springer Nature
ISBN: 3030565041
Category : Technology & Engineering
Languages : en
Pages : 304
Book Description
This open access book focuses on the practical application of electromagnetic polarimetry principles in Earth remote sensing with an educational purpose. In the last decade, the operations from fully polarimetric synthetic aperture radar such as the Japanese ALOS/PalSAR, the Canadian Radarsat-2 and the German TerraSAR-X and their easy data access for scientific use have developed further the research and data applications at L,C and X band. As a consequence, the wider distribution of polarimetric data sets across the remote sensing community boosted activity and development in polarimetric SAR applications, also in view of future missions. Numerous experiments with real data from spaceborne platforms are shown, with the aim of giving an up-to-date and complete treatment of the unique benefits of fully polarimetric synthetic aperture radar data in five different domains: forest, agriculture, cryosphere, urban and oceans.
Radar Polarimetry for Geoscience Applications
Author: Fawwaz Tayssir Ulaby
Publisher: Artech House Remote Sensing Li
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 398
Book Description
Offers the only consolidated reference on radar polarimetry design, analysis, and application and explains the most recent development in polarization system design and application. Illustrated with 150 figures, 10 tablets, and 9 full-color SAR images.
Publisher: Artech House Remote Sensing Li
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 398
Book Description
Offers the only consolidated reference on radar polarimetry design, analysis, and application and explains the most recent development in polarization system design and application. Illustrated with 150 figures, 10 tablets, and 9 full-color SAR images.
Inverse Synthetic Aperture Radar Imaging With MATLAB Algorithms
Author: Caner Ozdemir
Publisher: John Wiley & Sons
ISBN: 111952136X
Category : Technology & Engineering
Languages : en
Pages : 664
Book Description
Build your knowledge of SAR/ISAR imaging with this comprehensive and insightful resource The newly revised Second Edition of Inverse Synthetic Aperture Radar Imaging with MATLAB Algorithms covers in greater detail the fundamental and advanced topics necessary for a complete understanding of inverse synthetic aperture radar (ISAR) imaging and its concepts. Distinguished author and academician, Caner Özdemir, describes the practical aspects of ISAR imaging and presents illustrative examples of the radar signal processing algorithms used for ISAR imaging. The topics in each chapter are supplemented with MATLAB codes to assist readers in better understanding each of the principles discussed within the book. This new edition incudes discussions of the most up-to-date topics to arise in the field of ISAR imaging and ISAR hardware design. The book provides a comprehensive analysis of advanced techniques like Fourier-based radar imaging algorithms, and motion compensation techniques along with radar fundamentals for readers new to the subject. The author covers a wide variety of topics, including: Radar fundamentals, including concepts like radar cross section, maximum detectable range, frequency modulated continuous wave, and doppler frequency and pulsed radar The theoretical and practical aspects of signal processing algorithms used in ISAR imaging The numeric implementation of all necessary algorithms in MATLAB ISAR hardware, emerging topics on SAR/ISAR focusing algorithms such as bistatic ISAR imaging, polarimetric ISAR imaging, and near-field ISAR imaging, Applications of SAR/ISAR imaging techniques to other radar imaging problems such as thru-the-wall radar imaging and ground-penetrating radar imaging Perfect for graduate students in the fields of electrical and electronics engineering, electromagnetism, imaging radar, and physics, Inverse Synthetic Aperture Radar Imaging With MATLAB Algorithms also belongs on the bookshelves of practicing researchers in the related areas looking for a useful resource to assist them in their day-to-day professional work.
Publisher: John Wiley & Sons
ISBN: 111952136X
Category : Technology & Engineering
Languages : en
Pages : 664
Book Description
Build your knowledge of SAR/ISAR imaging with this comprehensive and insightful resource The newly revised Second Edition of Inverse Synthetic Aperture Radar Imaging with MATLAB Algorithms covers in greater detail the fundamental and advanced topics necessary for a complete understanding of inverse synthetic aperture radar (ISAR) imaging and its concepts. Distinguished author and academician, Caner Özdemir, describes the practical aspects of ISAR imaging and presents illustrative examples of the radar signal processing algorithms used for ISAR imaging. The topics in each chapter are supplemented with MATLAB codes to assist readers in better understanding each of the principles discussed within the book. This new edition incudes discussions of the most up-to-date topics to arise in the field of ISAR imaging and ISAR hardware design. The book provides a comprehensive analysis of advanced techniques like Fourier-based radar imaging algorithms, and motion compensation techniques along with radar fundamentals for readers new to the subject. The author covers a wide variety of topics, including: Radar fundamentals, including concepts like radar cross section, maximum detectable range, frequency modulated continuous wave, and doppler frequency and pulsed radar The theoretical and practical aspects of signal processing algorithms used in ISAR imaging The numeric implementation of all necessary algorithms in MATLAB ISAR hardware, emerging topics on SAR/ISAR focusing algorithms such as bistatic ISAR imaging, polarimetric ISAR imaging, and near-field ISAR imaging, Applications of SAR/ISAR imaging techniques to other radar imaging problems such as thru-the-wall radar imaging and ground-penetrating radar imaging Perfect for graduate students in the fields of electrical and electronics engineering, electromagnetism, imaging radar, and physics, Inverse Synthetic Aperture Radar Imaging With MATLAB Algorithms also belongs on the bookshelves of practicing researchers in the related areas looking for a useful resource to assist them in their day-to-day professional work.
Target Scattering Mechanism in Polarimetric Synthetic Aperture Radar
Author: Si-Wei Chen
Publisher: Springer
ISBN: 9811072698
Category : Technology & Engineering
Languages : en
Pages : 236
Book Description
This book presents new and advanced concepts, theories and methodologies in polarimetric synthetic aperture radar (PolSAR) target scattering mechanism modeling and interpretation, which is dedicated to bridge the gap between the acquired data and practical applications. It proposes adaptive and generalized polarimetric target decompositions, to precisely interpret the target scattering mechanisms. Further, it develops a uniform polarimetric matrix rotation theory and a polarimetric coherence pattern visualization and interpretation tool to completely explore and characterize the deep information and target signatures in the rotation domain. Finally, it demonstrates land cover classification, target detection, natural disaster damage investigation and mapping applications which use the novel scattering mechanism investigation tools. The book is a valuable resource for senior undergraduate and postgraduate students, teachers, engineers and researchers in the field of microwave remote sensing, radar polarimetry, imaging radar, and environmental studies.
Publisher: Springer
ISBN: 9811072698
Category : Technology & Engineering
Languages : en
Pages : 236
Book Description
This book presents new and advanced concepts, theories and methodologies in polarimetric synthetic aperture radar (PolSAR) target scattering mechanism modeling and interpretation, which is dedicated to bridge the gap between the acquired data and practical applications. It proposes adaptive and generalized polarimetric target decompositions, to precisely interpret the target scattering mechanisms. Further, it develops a uniform polarimetric matrix rotation theory and a polarimetric coherence pattern visualization and interpretation tool to completely explore and characterize the deep information and target signatures in the rotation domain. Finally, it demonstrates land cover classification, target detection, natural disaster damage investigation and mapping applications which use the novel scattering mechanism investigation tools. The book is a valuable resource for senior undergraduate and postgraduate students, teachers, engineers and researchers in the field of microwave remote sensing, radar polarimetry, imaging radar, and environmental studies.
Remote Sensing with Imaging Radar
Author: John A. Richards
Publisher: Springer Science & Business Media
ISBN: 3642020208
Category : Technology & Engineering
Languages : en
Pages : 376
Book Description
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.
Publisher: Springer Science & Business Media
ISBN: 3642020208
Category : Technology & Engineering
Languages : en
Pages : 376
Book Description
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.
Polarimetric Microwave Imaging
Author: Ruliang Yang
Publisher: Springer Nature
ISBN: 981158897X
Category : Technology & Engineering
Languages : en
Pages : 611
Book Description
This book introduces readers to the polarimetric synthetic aperture radar (PolSAR) system, its information processing, and imaging applications. The content is divided into three main parts: Part I, on the research scope of PolSAR, addresses the underlying theory and system design, polarimetric SAR interferometry (PolInSAR), compact PolSAR, and calibration of PolSAR. Part II, which focuses on information processing, highlights the new theories and methods used in PolSAR, such as statistical properties analysis for images, speckle reduction, image enhancement, polarimetric target decomposition, and classification of PolSAR target detection. In turn, Part III, on the applications of polarimetric SAR, discusses the geophysical parameter retrieval of PolSAR data, polarimetric interferometric SAR information processing, compact polarimetric interferometric SAR information processing, and the effects of terrain tilt in azimuth direction on PolSAR data. The book provides a comprehensive and systematic guide to the system, integrating theory and practice, and has a highly application-oriented focus. Presenting new theories, methods and achievements made in polarimetric microwave imaging in recent years, it offers a valuable asset for researchers, engineers and scientists in the area of remote sensing and radar imaging. It can also be used as a reference book for university educators and graduate students.
Publisher: Springer Nature
ISBN: 981158897X
Category : Technology & Engineering
Languages : en
Pages : 611
Book Description
This book introduces readers to the polarimetric synthetic aperture radar (PolSAR) system, its information processing, and imaging applications. The content is divided into three main parts: Part I, on the research scope of PolSAR, addresses the underlying theory and system design, polarimetric SAR interferometry (PolInSAR), compact PolSAR, and calibration of PolSAR. Part II, which focuses on information processing, highlights the new theories and methods used in PolSAR, such as statistical properties analysis for images, speckle reduction, image enhancement, polarimetric target decomposition, and classification of PolSAR target detection. In turn, Part III, on the applications of polarimetric SAR, discusses the geophysical parameter retrieval of PolSAR data, polarimetric interferometric SAR information processing, compact polarimetric interferometric SAR information processing, and the effects of terrain tilt in azimuth direction on PolSAR data. The book provides a comprehensive and systematic guide to the system, integrating theory and practice, and has a highly application-oriented focus. Presenting new theories, methods and achievements made in polarimetric microwave imaging in recent years, it offers a valuable asset for researchers, engineers and scientists in the area of remote sensing and radar imaging. It can also be used as a reference book for university educators and graduate students.
Radar Imaging for Maritime Observation
Author: Fabrizio Berizzi
Publisher: CRC Press
ISBN: 1315356678
Category : Political Science
Languages : en
Pages : 297
Book Description
Based on the experiences of the Department of Information Engineering of the University of Pisa and the Radar and Surveillance System (RaSS) national laboratory of the National Interuniversity Consortium of Telecommunication (CNIT), Radar Imaging for Maritime Observation presents the most recent results in radar imaging for maritime observation. The book explores both the areas of sea surface remote sensing and maritime surveillance providing key theoretical concepts of SAR and ISAR imaging and more advanced and ad-hoc techniques for applications in maritime scenarios. The book is organized in two sections. The first section discusses the fundamentals of standard SAR/ISAR processing and novel imaging techniques, such as Bistatic, Passive, and, 3D Interferometric ISAR. The second section focuses on the applications and results obtained by processing real data from maritime observations like SAR image processing for oil spill, detection in SAR images and fractal analysis. Useful to both beginners and experts in maritime observation, this book provides several examples of (mainly space-borne) radar imaging of maritime targets. Nevertheless, the same principles and techniques apply to the case of manned or unmanned carriers and to ground and air moving targets.
Publisher: CRC Press
ISBN: 1315356678
Category : Political Science
Languages : en
Pages : 297
Book Description
Based on the experiences of the Department of Information Engineering of the University of Pisa and the Radar and Surveillance System (RaSS) national laboratory of the National Interuniversity Consortium of Telecommunication (CNIT), Radar Imaging for Maritime Observation presents the most recent results in radar imaging for maritime observation. The book explores both the areas of sea surface remote sensing and maritime surveillance providing key theoretical concepts of SAR and ISAR imaging and more advanced and ad-hoc techniques for applications in maritime scenarios. The book is organized in two sections. The first section discusses the fundamentals of standard SAR/ISAR processing and novel imaging techniques, such as Bistatic, Passive, and, 3D Interferometric ISAR. The second section focuses on the applications and results obtained by processing real data from maritime observations like SAR image processing for oil spill, detection in SAR images and fractal analysis. Useful to both beginners and experts in maritime observation, this book provides several examples of (mainly space-borne) radar imaging of maritime targets. Nevertheless, the same principles and techniques apply to the case of manned or unmanned carriers and to ground and air moving targets.