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Preface

Abdourrahmane M. ATTO1, Francesca BOVOLO2 and Lorenzo BRUZZONE3

1University Savoie Mont Blanc, Annecy, France

2Fondazione Bruno Kessler, Trento, Italy

3University of Trento, Italy

This book is part of the ISTE-Wiley “SCIENCES” Encyclopedia and belongs to the Image field of the Engineering and Systems department. The Image field covers the entire processing chain from acquisition to interpretation by analyzing the data provided by various imaging systems. This field is split into seven subjects, including Remote Sensing Imagery (RSI). The heads of this subject are Emmanuel Trouvé and Avik Bhattacharya. In this subject, we propose a series of books that portray diverse and comprehensive topics in advanced remote-sensing images and their application for Earth Observation (EO). There has been an increasing demand for monitoring and predicting our planet’s evolution on a local, regional and global scale. Hence, over the past few decades, airborne, space-borne and ground-based platforms with active and passive sensors acquire images that measure several features at various spatial and temporal resolutions.

RSI has become a broad multidisciplinary domain attracting scientists across the diverse fields of science and engineering. The aim of the books proposed in this RSI series is to present the state-of-the-art and available scientific knowledge about the primary sources of images acquired by optical and radar sensors. The books cover the processing methods developed by the signal and image processing community to extract useful information for end-users for an extensive range of EO applications in natural resources.

In this project, each RSI book focuses on general topics such as change detection, surface displacement measurement, target detection, model inversion and data assimilation. This first book of the RSI series is dedicated to Change Detection and Image Time Series Analysis. It presents methods developed to detect changes and analyze their temporal evolutions using optical and/or synthetic aperture radar (SAR) images in diverse settings (e.g. image pairs, image time series). According to the numerous works and applications in this domain, this book is divided into two volumes, dedicated to unsupervised and supervised approaches, respectively. Unsupervised methods require little to no expert-based information to resolve a problem, whereas the contrary holds true, especially for methods that are supervised in the sense of providing a wide amount of labeled training data to the method, before testing this method.

Volume 1: Unsupervised methods

A significant part of this book is dedicated to a wide range of unsupervised methods. The first chapter provides an insight into the motivations of this behavior and introduces two unsupervised approaches to multiple-change detection in bitemporal multispectral images. Chapters 2 and 3 introduce the concept of change detection in time series and postulate it in the context of statistical analysis of covariance matrices. The former chapter focuses on a directional analysis for multiple-change detection and exercises on a time series of SAR polarimetric data. The latter focuses on local analysis for binary change detection and proposes several covariance matrix estimators and their corresponding information-theoretic measures for multivariate SAR data. The last four chapters focus more on applications. Chapter 4 addresses functional representations (wavelets and convolutional neural network filters) for feature extraction in an unsupervised approach. It proposes anomaly detection and functional evolution clustering from this framework by using relative entropy information extracted from SAR data decomposition. Chapter 5 deals with the selection of metrics that are sensitive to snow state variation in the context of the cryosphere, with a focus on mountain areas. Metrics such as cross-correlation ratios and Hausdorff distance are analyzed with respect to optimal reference images to identify optimal thresholding strategies for the detection of wet snow by using Sentinel-1 image time series. Chapter 6 presents time series analysis in the context of spatio-temporal forecasting and monitoring fast-moving meteorological events such as cyclones. The application benefits from the fusion of remote sensing data under the fractional dynamic field assumption on the cyclone behavior. Chapter 7 proposes an analysis based on characteristic points for texture modeling with graph theory. Such an approach overcomes issues arising from large-size dense neighborhoods that affect spatial context-based approaches. The application proposed in this chapter concerns glacier flow measurement in bitemporal images. Chapter 8 focuses on detecting new land-cover types by classification-based change detection or feature/pixel-based change detection. Monitoring the construction of new buildings in urban and suburban scenarios at a large regional scale by means of Sentinel-1 and -2 images is considered as an application. Chapter 9 focuses on the statistical modeling of classes in the difference image and derives from scratch a multiclass model for it in the context of change vector analysis.

Volume 2: Supervised methods

The second volume of this book is dedicated to supervised methods. Chapter 1 of this volume addresses the fusion of multisensor, multiresolution and multitemporal data. This chapter reviews recent advances in the literature and proposes two supervised Markov random field-based solutions: one relies on a quadtree and the second one is specifically designed to deal with multimission, multifrequency and multiresolution time series. Chapter 2 provides an overview of pixel-based methods for time series classification from the earliest shallow-learning methods to the most recent deep learning-based approaches. This chapter also includes best practices for reference data preparation and management, which are crucial tasks in supervised methods. Chapter 3 focuses on very high spatial resolution data time series and the use of semantic information for modeling spatio-temporal evolution patterns. Chapter 4 focuses on the challenges of dense time series analysis, including pre-processing aspects and a taxonomy of existing methodologies. Finally, since the evaluation of a learning system can be subject to multiple considerations, Chapters 5 and 6 propose extensive evaluations of the methodologies used to produce earthquake-induced change maps, with an emphasis on their strengths and shortcomings (Chapter 5) and the deep learning systems in the context of multiclass multilabel change-of-state classification on glacier observations (Chapter 6).

This book covers both methodological and application topics. From the methodological viewpoint, contributions are provided with respect to feature extraction and a large number of evaluation metrics for change detection, classification and forecasting issues. Analysis has been performed in both bitemporal images and time series, illustrating both unsupervised and supervised methods and considering both binary- and multiclass outputs. Several applications are mentioned in the chapters, including agriculture, urban areas and cryosphere analysis, among others. This book provides a deep insight into the evolution of change detection and time series analysis in the state-of-the-art, as well as an overview of the most recent developments.

July 2021