Si-Wei Chen

National University of Defense Technology | NUDT · Department of Electronic Science

Ship monitoring is an important application of synthetic aperture radar (SAR). The constant false alarm rate (CFAR) methods are commonly used for ship detection. However, CFAR detectors usually face challenges for inshore dense ship detection. Due to the significant mixture of ship candidates and sea clutters within the clutter window, the detectio...

Ship detection is an important task in civil or military applications and we can use polarimetric synthetic aperture radar (PolSAR). Many polarimetric detectors were proposed and achieved good performances in particular environments, such as optimal polarimetric detector (OPD), polarimetric whitening filter (PWF), polarimetric notch filter (PNF), p...

Polarimetric radar can acquire complete polarization information and is widely used in many applications. However, target orientation relative to the radar line of sight usually exhibits significant influences on the scattering mechanisms. Recently, such target scattering diversity has been successfully characterized and utilized with the polarimet...

Manmade targets with various orientations usually exhibit scattering diversity which makes polarimetric radar target recognition difficult. The recently developed polarimetric rotation domain techniques provide solutions to understand and utilize target scattering diversity. Meanwhile, the Null-Pol theory is the important component of target optima...

Man-made target recognition is of great significance for many applications within microwave remote sensing. The scattering diversity of various man-made target structures makes radar target identification a difficult task. This work aims at mitigating this issue by mining and utilization of man-made target scattering diversity in polarimetric rotat...

Ship detection is one of important applications for synthetic aperture radar (SAR). Speckle effects usually make SAR image understanding difficult and speckle reduction becomes a necessary pre-processing step for majority SAR applications. This work examines different speckle reduction methods on SAR ship detection performances. It is found out tha...

Speckle filtering of synthetic aperture radar (SAR) image is a necessary pre-processing for many subsequent applications. The challenge lies in how to adaptively select a sufficient number of similar pixels for an unbiased estimator generation. A novel SAR speckle filter is proposed and the core idea contains two aspects. Firstly, a context covaria...

The recognition of partially occluded targets is a difficult problem in the field of synthetic aperture radar (SAR) target recognition. To eliminate the effect of occlusion, the intuitive idea is to determine the exact location and the size of the occluded area. However, this is very difficult, even impossible in practice. In order to avoid this di...

Speckle filtering of polarimetric synthetic aperture radar (PolSAR) data is a necessary preprocessing step for many subsequent applications. The performances of speckle reduction and details preservation are primarily determined by the scheme of similar pixel selection. This letter mainly contributes to establish a novel approach for adaptive and e...

For polarimetric synthetic aperture radar (PolSAR) data, the correlation of two polarization channels is sensitive to the target orientation relative to the sensor's illumination direction. In this letter, the concept of polarimetric correlation pattern is proposed to explore this scattering diversity. The core idea is to extend the polarimetric co...

The backscattering of radar targets is sensitive to the relative geometry between targets' orientations and the radar. This target scattering diversity makes mechanism interpretation and quantitative application difficult. This study reviews a newly established theory for target scattering mechanism interpretation in the rotation domain. It contain...

Ship detection in polarimetric SAR (PolSAR) image plays an important role in marine monitoring. From the viewpoint of the attention mechanism, ship targets can be salient candidates from sea clutter. A novel saliency detector for PolSAR ship detection has been proposed in this paper. The core idea is to explore the different scattering mechanisms b...

Distributed radars have the potential to combine coherently for achieving a high signal-to-noise ratio (SNR) while maintaining a moderate antenna size. The key to coherently combining multiple radars is obtaining accurate coherent parameters (CPs), which are used to adjust the transmitting/receiving time and phase of each radar. One approach for CP...

Polarimetric response is strongly target orientation dependent which is known as the orientation diversity effect. The observed polarimetric matrices from the same target with different orientations can be quite different.

This chapter summarizes the development of the visualization and characterization tool of polarimetric coherence pattern for PolSAR data investigation. The core idea is to extend the traditional polarimetric coherence at a given rotation state to the rotation domain along the radar line of sight for hidden information exploration.

The occurrence of the observed natural disasters, such as earthquakes and tsunamis, appears to have increased in recent decades. Quick observation of the damage caused by an earthquake and tsunami is extremely important for planning effective rescue operations.

In past decades, many scientists and researchers have been involved in the field of interpreting scattering mechanisms presenting in PolSAR data. Polarimetric target decomposition has become one of the most powerful and the most popularly used techniques.

With the progresses and advances in hardware technologies and signal processing theories, the definition and function of radar have been greatly expanded. Modern radar can generate a radar image to “see” target directly.

Accurate detection and identification of destructed urban areas are essentially important for rescue planning after a large-scale natural disaster (e.g., earthquake, tsunami). Spaceborne synthetic aperture radar (SAR) can provide quick response and huge area monitoring to mitigate the further loss. Due to the layover, speckle effect, multiple scatt...

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 pre...

Polarimetric synthetic aperture radar (PolSAR) image classification is an important application. Advanced deep learning techniques represented by deep convolutional neural network (CNN) have been utilized to enhance the classification performance. One current challenge is how to adapt deep CNN classifier for PolSAR classification with limited train...

Backscattering of radar targets is sensitive to the relative geometry between target orientations and the radar line of sight. This scattering diversity makes imaging radar represented by polarimetric Synthetic Aperture Radar (SAR) information processing and applications very difficult. This situation has become one of the main bottlenecks in the i...

Terrain classification is an important application for understanding and interpreting Polarimetric Synthetic Aperture Radar (PolSAR) images. One common PolSAR terrain classification uses roll-invariant feature parameters such as H/A/a/SPAN. However, the back scattering response of a target is closely related to its orientation and attitude. This fr...

Land cover classification is an important application for polarimetric synthetic aperture radar (PolSAR) data utilization. Rollinvariant polarimetric features such as H / Ani / α / Span are commonly adopted in PolSAR land cover classification. However, target orientation diversity effect makes PolSAR images understanding and interpretation difficul...

Land cover classification is an important application for polarimetric synthetic aperture radar (PolSAR). Target polarimetric response is strongly dependent on its orientation. Backscattering responses of the same target with different orientations to the SAR flight path may be quite different. This target orientation diversity effect hinders PolSA...

In synthetic aperture radar (SAR) images, scattering centers (SCs) from the same geometric structure of the man-made target usually have the same scattering type and similar coordinates. Inspired by this observation, a novel clustering-based geometrical structure retrieval (C-GSR) method is proposed to estimate the geometrical structure of targets...

A quick response to a large-scale natural disaster such as earthquake and tsunami is vital to mitigate further loss. Remote sensing, especially the spaceborne sensors, provides the possibility to monitor a very large scale area in a short time and with regular revisit circle. Damage ranges and damage levels of the destructed urban areas are extreme...

A quick response to a large-scale natural disaster such as earthquake and tsunami is vital to mitigate further loss. Remote sensing, especially the spaceborne sensors, provides the possibility to monitor a very large scale area in a short time and with regular revisit circle. Damage ranges and damage levels of the destructed urban areas are extreme...

Quick response to a large-scale natural disaster such as earthquake and tsunami is vital to mitigate the further loss. Remote sensing especially the spaceborne sensors provide the solution to monitor a huge area in a short time and with regular revisit circle. Damage ranges and damage levels of the destructed urban areas are extremely important inf...

Crop discrimination is a necessary step for most agricultural monitoring systems. Radar polarimetric responses from various crops strongly relate to the types and orientations of the local scatterers, which makes the discrimination still difficult using the polarimetric synthetic aperture radar (PolSAR) technique. This work provides a new approach...

Tri-polarised antennas are exploited to synthesise the optimal polarised beampattern in this study. First, the characteristics of a single tri-polarised antenna are studied with an infinite current sheet model. Using the cross-product algorithm, the authors find that three co-located orthogonal current sheets are equivalent to a pair of orthogonal...

This paper focuses on earthquake/tsunami damage investigation over urban areas by exploring the multitemporal spaceborne ALOS/PALSAR PolSAR data. The polarimetric scattering mechanism changes before- and after-tsunami, at the city block scale, have been examined using model-based decomposition and PO angle techniques. These analyzes are used to est...

This paper focuses on earthquake/tsunami damage investigation over urban areas by exploring the multi-temporal spaceborne ALOS/PALSAR PolSAR data. The polarimetric scattering mechanism changes before- and after-tsunami, at the city block scale, have been examined using model-based decomposition and PO angle techniques. These analyzes are used to es...

This paper presents the development of a uniform polarimetric matrix rotation theory in the rotation domain along the radar line of sight for polarimetric synthetic aperture radar (PolSAR) data interpretation. The uniform representation of each coherency matrix element is a sinusoidal function in the rotation domain. A set of oscillation parameters...

Polarimetric target decomposition is a powerful technique to interpret scattering mechanisms in polarimetric synthetic aperture radar (PolSAR) data. Eigenvalue-?eigenvector-based and model-based methods are two main categories within the incoherent decomposition techniques. Eigenvalue-eigenvector-based decomposition becomes relatively mature since...

Polarimetric coherence strongly relates to the types and orientations of local scatterers. An optimization scheme is proposed to optimize the coherence between two polarimetric channels for polarimetric SAR (PolSAR) data. The coherence magnitude (correlation coefficient) is maximized by rotating a polarimetric coherence matrix in the rotation domai...

Orientation angle compensation was incorporated into model-based decomposition to cure overestimation of the volume scattering contribution for interpretation of polarimetric synthetic aperture radar (PolSAR) data. The compensation is based on rotating the coherency matrix to minimize the cross-polarization term. However, this processing cannot alw...

The overestimation of volume scattering power and the scattering mechanism ambiguity are still present in model-based decompositions even with the implementation of the deorientation processing. These effects are demonstrated and investigated. One possible reason is because of the limited dynamic range of the models themselves that are not fully sa...

This paper presents the development of a uniform polarimetric matrix rotation theory in the rotation domain along the radar line of sight for polarimetric SAR (PolSAR) data interpretation. The uniform representation of each coherency matrix element is a sinusoidal function in the rotation domain. A set of oscillation parameters, including oscillati...

SAR Interferometry is a common methodology for detection of Natural disaster affected area. However, we applied radar polarimetric analysis to ALOS/PALSRA data sets to investigate the possibility of detection of Tsunami affected area only from the SAR data acquired after the event. The resolution of the SAR image is 30m by 30m and cannot identify e...

This paper explores the use of full polarimetric synthetic aperture radar (PolSAR) images for tsunami damage investigation from the polarimetric viewpoint. The great tsunami induced by the earthquake of March 11th, 2011, which occurred beneath the Pacific off the northeastern coast of Japan, is adopted as the study case using the Advanced Land Obse...

Subarray partition is usually employed in the design of array antennas. However, it is difficult to get an exact partition of an arbitrary antenna aperture with irregular-shaped subarrays. Based on the exact cover theory, a solution of the exact partition is developed using the algorithm X. We consider the fact that sometimes it would be unpractica...

By using the difference of the scattering mechanism from targets, SAR polarimetry has very high potential to detect the natural disaster damaged areas. This is a very important advantage of using SAR polarimetry compared to the SAR interferometry, because we do not need the SAR images before the event. We demonstrated that the tsunami damaged area...

Orientation angle compensation has been incorporated into model-based decomposition to cure the overestimation of volume scattering contribution, by rotating the coherency matrix to minimize the cross-polarization term. However, this processing cannot always guarantee to rotate the double- and odd-bounce scattering components back to zero orientati...

Most polarimetric synthetic aperture radar interferometry (PolInSAR) data processing procedures and their applications are based on the polarimetric complex coherence descriptor. The reliable estimation of the complex coherence requires selecting sufficient homogeneous pixels for generating an unbiased estimator. In this paper, two indicators using...

Orientation angle compensation has been incorporated into model-based decomposition to cure the overestimation of volume scattering contribution, by rotating the coherency matrix to minimize the cross-polarization term. However, this processing cannot always guarantee to rotate the double-and odd-bounce scattering components back to zero orientatio...

A volume scattering model utilizing polarimetric SAR interferometry (PolInSAR) coherence is proposed. The new model is more adaptive and better fit for both forest and skew-oriented built-up areas. Thereby, a new model-based polarimetric decomposition scheme is developed. The advantage of the proposed method is demonstrated by ESAR PolInSAR data. A...

In this study, we consider tree vertical profile with a higher order truncation of Fourier-Legendre series using polarization coherence tomography. An improved method based on Freeman-Durben decomposition is employed to estimate tree height and surface phase. A contrast to single-baseline scenario is performed. The primary scattering mechanisms and...

A new approach for estimation of tree root biomass by using a GPR system with a high accuracy positioning system is proposed. 3D images of subsurface can be obtained clearly with this system, which we refer as “3DGPR”. We try to estimate the biomass of tree roots quantitatively by measuring the volume of the tree roots. We tested this system for tr...