Wu Yirong

An Improved Cloude-Pottier Decomposition Using H/α/SPAN and Complex Wishart Classifier for Polarimetric SAR Classification

An improvement is proposed for the Cloude-Pottier decomposition using H/α/SPAN and IHSL transform. Based on this decomposition, an unsupervised classification with SPAN is also given in this paper. The main advantages of this decomposition are that it uses SPAN to maintain the space information for further polarimetric analysis and provides a straight way to present the result. Our experiments show that this decomposition method provides better results than the general Cloude-Pottier method and the corresponding Wishart H/α/SPAN classification also achieves better performance than the current Wishart H/α/A method

Analytic modeling and three-dimensional imaging of downward-looking SAR using bistatic uniform linear array antennas

The bistatic configuration of linear array with one central antenna element for transmitting and the other antenna elements of linear array for receiving is introduced in downward-looking SAR for three-dimensional imaging in this paper. The geometrical model and the received signal model of downward-looking SAR using bistatic uniform linear array antennas are established. The analytic expression of three-dimensional imaging results is derived and the resolutions in three dimensions are given. This paper presents the image formation and analyzes the simulation results based on this 3D imaging concept.

Introduction on an experimental airborne InSAR system

This paper gives a technical description of the system hardware, data processing flow as well as experimental results of the Experimental Airborne InSAR System, developed by Institute of Electronics, Chinese Academy of Sciences and sponsored by the Information Technology Committee of Chinese High-Tech Program. The system operates in X-band range and is configured as a dual-antennae cross-track interferometric SAR with the main parameters: 9.6GHz operating frequency, 100 MHz bandwidth, 0.60 m baseline, up to 10 km swath width, 2m×2m ground resolution, excelled 5m height accuracy, and two polarized types.

Maximal effective baseline for polarimetric interferometric SAR forest height estimation

The concepts of critical baseline and maximal effective baseline have been defined for interferometric SAR (InSAR) DEM application based on the spatial decorrelation (which is a function of baseline). This paper puts forward these two concepts to polarimetric interferometric SAR (Pol-InSAR) forest height estimation application. The application makes use of volume decorrelation, which is also a function of baseline. So both the spatial decorrelation and volume decorrelation are considered to determine Pol-InSAR critical and maximal effective baseline. Firstly various decorrelation effects are discussed. Then the calculation formula of Pol-InSAR maximal effective baseline are presented and compared to that of InSAR. For validation, RVoG-based and PolSARpro-based simulation data and DLR ESAR data are used. The concept of Pol-InSAR maximal effective baseline is of practical significance in selection of Pol-InSAR image pairs as well as in the design of further Pol-InSAR systems.

An efficient rotation-invariance remote image matching algorithm based on feature points matching

In this paper, a matching method based on feature points matching is proposed. First, a point detector is used to detect interest points of a source image and a target image. Then genetic algorithms (GAs), which are useful in finding global optima, are used to match the detected points. A fitness function which is proven rotation-invariance is proposed to measure the similarity of two points in the paper. According to the results of the GAs, the corresponding points of the target image are found in the source image. The algorithm can overcome the rotation distortion of the images. The experiment results confirm the proposed algorithm is efficient and robust.

Application of inverse chirp-z transform in wideband radar

Pulse stepped frequency radar is a kind of wideband radar technique. It can obtain high range resolution by correct signal processing methods. One of most important methods is the inverse Fourier transform method. This method can realize pulse compression by the coherent sum of a series of echoes. Although the inverse Fourier transform method is very useful, the number of echo series limits the sampling resolution. In order to improve the sampling resolution at a fixed number of echo series, a special inverse chirp-z transform method is presented in this paper. This special inverse chirp-z transform method has all the features of the inverse Fourier transform method. It can compress a series of pulse signals and increase sampling resolution within a range profile window.

Large beamwidth spaceborne SAR processing using chirp scaling

The accurate effective platform velocity and the effective closest approach range should be used to get a high resolution image when the chirp scaling algorithm (CSA) is employed in spaceborne SAR processing, especially, in the large beamwidth and squint modes. In this paper the two effective parameters are derived as a function of the Doppler centroid and the Doppler rate. Therefore, the classical clutterlock and autofocus methods can be used in CSA to get precise estimates of the effective parameters. Simulation results show that CSA using the effective velocity and closest slant range is suitable for L-band large beamwidth spaceborne SAR processing.

Analysis of 3D-SAR based on Angle Compression Principle

This paper presented the 3D-SAR based on angle compression principle which could, in contrast to conventional single-channel 2D-SAR, create the real 3D resolution cells to avoid geometric distortions. Except for conventional side-looking mode, 3D-SAR system herein can be operated in downward-looking mode which can avoid shadowing effects. The angle compression principle and the angular ambiguity problem are analyzed in this paper. The analytic expression of angle compression and the condition which should be satisfied to avoid angular ambiguity are also derived in this part. The demonstration of the feasibility of the 3D-SAR based on angle compression principle and the angular ambiguity problem are given by simulation in the last part of this paper.This paper presented the 3D-SAR based on angle compression principle which could, in contrast to conventional single-channel 2D-SAR, create the real 3D resolution cells to avoid geometric distortions. Except for conventional side-looking mode, 3D-SAR system herein can be operated in downward-looking mode which can avoid shadowing effects. The angle compression principle and the angular ambiguity problem are analyzed in this paper. The analytic expression of angle compression and the condition which should be satisfied to avoid angular ambiguity are also derived in this part. The demonstration of the feasibility of the 3D-SAR based on angle compression principle and the angular ambiguity problem are given by simulation in the last part of this paper.

Analysis of fully polarimetric SAR data based on the Cloude-Pottier decomposition and the complex Wishart classifier

An estimation of the number of clusters is proposed for fully polarimetric SAR data analysis, and a corresponding unsupervised segmentation algorithm is also given based on the Cloude-Pottier decomposition and the complex Wishart clustering. The Monte-Carlo Cross-Validation (MCCV) is used to estimate the optimal number of clusters to reveal the inner structure of the data. Since it is a quantitative estimation of the classification performance, the MCCV algorithm also has the potential capability to perform the unsupervised segmentation validation. The effectiveness of the MCCV estimation and the segmentation algorithm is demonstrated using ESAR data acquired.

Circular SAR experiment for human body imaging

In this paper, the CSAR (circular synthetic aperture radar) technique is introduced firstly. The principle of CSAR 3D (three dimensional) imaging and the spatial wavenumber support are analyzed and the 3D resolution is discussed secondly. Secondly, Ku band fully-polarimetric CSAR human body imaging experiments are performed, and the experimental data is processed by a fast 3D backprojection algorithm, the corresponding amplitude images are shown. Finally, the future experiments for human body imaging are discussed.