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Vertex extraction-guided local back-projection algorithm for velocity estimation using ground penetrating radar data

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INTERNATIONAL JOURNAL OF REMOTE SENSING 2022年第13期43卷 4853-4871页

作者： Xu, Zihan Su, Fulin Xu, Guodong Harbin Inst Technol Sch Elect & Informat Engn 92 Xidazhi St Harbin 150001 Heilongjiang Peoples R China

Estimating the velocity of electromagnetic waves in the medium is essential for ground penetrating radar (GPR) to reconstruct target scenes. However, the existing velocity estimation methods based on imaging algorithms, e.g. the back-projection (BP)- and the Stolt migration-based methods, are susceptible to clutter and cannot strike a balance between depth independence and computational efficiency. Therefore, a velocity estimation method is proposed based on the vertex extraction-guided local BP algorithm. Initially, the high-order moment (HOM) is introduced into GPR data by analysing the distributions of target hyperbolas and clutter. Designed to avoid clutter, the proposed HOM sliding window extracts the hyperbola vertex at a high signal-to-clutter ratio region. By virtue of the extracted vertex, the local hyperbola region is subsequently extracted to reduce computation. Additionally, this paper adopts the depth-independent BP algorithm and further develops a local BP algorithm utilizing its imaging flexibility. Guided by the extracted vertex, the proposed local BP algorithm is iteratively performed on the local hyperbola region to estimate the velocity by a focus metric. Comprehensive experiments demonstrate the effectiveness and robustness of the proposed velocity estimation method. The proposed method outperforms the existing methods in clutter robustness, computational efficiency, and depth independence.

关键词： Ground penetrating radar velocity estimation back-projection algorithm vertex extraction high-order moment

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An Improved back-projection algorithm for Magnetic Induction Tomography Based on Magnetic Field Lines 7

An Improved Back-Projection Algorithm for Magnetic Induction...

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7th International Conference on Biomedical Engineering and Informatics (BMEI)

作者： Ke, Li Cao, Fengqiu Du, Qiang Shenyang Univ Technol Inst Biomed & Electromagnet Engn Shenyang Peoples R China Shenyang Pharmaceut Univ Sch Med Devices Shenyang Peoples R China

ISBN: (纸本)9781479958382

Magnetic induction tomography (MIT) is a non-invasive and non-contact medical imaging technology. It is a visualized implementation based on image reconstruction algorithms, which plays an important role in determining the image quality. In this paper, an improved back-projection algorithm based on magnetic field lines is presented and can be described as follows. Firstly, the phase data collected at the imaging region boundary coil is normalized. Secondly, the back-projection matrix is simply weighted based on the difference of back-projection paths and the sensitivity to conductivity change of the pixel in the imaging region. Finally, a data modification model is proposed based on the electromagnetic relation in MIT. The results show that the improved algorithm can accurately reflect the distribution of conductivity and the object position in the imaging region with a high resolution. Specifically, when the object is located at the boundary of the imaging region, the back-projection algorithm of MIT can improve the convergence of the edge of the detected object. The anti-noise performance of improved algorithm could meet the standard of applications. In a measurement system with SNR is over 20dB, images could be successfully reconstructed without being affected by the noise.

关键词： Magnetic induction tomography (MIT) image reconstruction algorithms back-projection algorithm standardized data simply weighted

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DEM-ASSISTED back-projection algorithm IN HIGH RESOLUTION GEOSYNCHRONOUS SAR IMAGING 36

DEM-ASSISTED BACK-PROJECTION ALGORITHM IN HIGH RESOLUTION GE...

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36th IEEE International Geoscience and Remote Sensing Symposium (IGARSS)

作者： Li, YuanHao Dong, XiChao Cui, Kai Hu, Cheng Ao, DongYang Long, Teng Beijing Inst Technol Sch Informat & Elect Beijing 100081 Peoples R China Beijing Key Lab Embedded Real Time Informat Proc Beijing 100081 Peoples R China

ISBN: (纸本)9781509033324

Since geosynchronous synthetic aperture radar (GEO SAR) has curved trajectories, back-projection algorithm (BPA) greatly fits for its imaging. However, for a scene with height variation, the reference range based on the fixed-height imaging grid under curved trajectories is inaccurate in azimuth back-projection. Resultantly, the GEO SAR image quality will be obviously deteriorated in high resolution imaging. To address the issue, this paper proposed the digital elevation model (DEM)-assisted BPA to realize the accurate high resolution GEO SAR imaging for the scene with height variation. DEM information is utilized to construct the imaging grid in the new method for generating the accurate reference range. Simulation results validate that the proposed method achieves good imaging performance for the scene with height variation.

关键词： SAR imaging GEO SAR back-projection algorithm DEM

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Conical Differential Range Based back-projection algorithm for Concealed Object Detection with Three-Dimensional mmW Imaging

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TRAITEMENT DU SIGNAL 2022年第6期39卷 1981-1989页

作者： Duysak, Huseyin Yigit, Enes Seyfi, Levent Karamanoglu Mehmetbey Univ Dept Elect Elect Engn TR-70200 Karaman Turkey Bursa Uludag Univ Dept Elect Elect Engn TR-16059 Bursa Turkey Konya Tech Univ Dept Elect Elect Engn TR-42250 Konya Turkey

Millimeter wave(mmW) imaging has spread to a wide range of applications in the last quarter. One of the most important research areas of mmW is three-dimensional (3D) imaging systems. In this study, conical differential range-based back-projection (BP) algorithm is proposed for three-dimensional mmW imaging. In the algorithm, the differential range is created using points inside a conical volume, thus the number of interpolation points is considerably reduced. The performance of the algorithm is demonstrated by simulation and experimental studies. Cylindrical scanning is carried out by means of the experimental setup. Experiments are carried out at frequencies of 26.5-40 GHz. The traditional BP algorithm (BPA) and the proposed algorithm are used to reconstruct the images. With the proposed method, it is observed that ISLR for the point target increased by about 5 dB compared to the traditional method. Moreover, the computational complexity is reduced by up to 10 times, depending on the imaging area. Thanks to the proposed method, the image of the concealed weapon under the cloth in an experimental study is more clearly focused compared to the traditional method. Therefore, it can provide images that give more accurate results for applications such as automatic target detection methods.

关键词： millimeter-wave imaging radar imaging back-projection algorithm

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A Fast Cartesian back-projection algorithm Based on Ground Surface Grid for GEO SAR Focusing

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IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING 2022年 60卷 1页

作者： Chen, Quan Liu, Wenkang Sun, Guang-Cai Chen, Xiaoxiang Han, Liang Xing, Mengdao Xidian Univ Natl Lab Radar Signal Proc Xian 710071 Peoples R China Xidian Univ Collaborat Innovat Ctr Informat Sensing & Underst Xian 710071 Peoples R China Xidian Univ Acad Adv Interdisciplinary Res Xian 710071 Peoples R China Xidian Univ Phys & Optoelect Engn Xian 710071 Peoples R China

Geosynchronous-Earth-orbit (GEO) synthetic aperture radar (SAR) provides excellent continuous observing capability and large swath. However, the extremely long synthetic aperture time, the curved orbit, and the nonplanar ground surface cause serious spatial variance in the GEO SAR signal. In this article, a novel fast Cartesian back-projection (BP) algorithm based on subaperture imaging on ground and multistage fusion is proposed for accurately and efficiently imaging of GEO SAR. The imaging grids are arranged on the ground surface to avoid the azimuth defocusing caused by the flat ground approximation. Then, a new two-step spectrum compression method is derived to solve the spectrum aliasing of subaperture images. Also, a multistage image fusion method is adopted to combine all the subaperture images with high efficiency. The computational complexity and the approximation of the proposed algorithm are also discussed. Simulation results verify the effectiveness of the proposed algorithm.

关键词： back-projection algorithm geosynchronous-Earth-orbit (GEO) synthetic aperture radar (SAR) ground surface curvature spectrum compression

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A back-projection algorithm to Stepped-Frequency Synthetic Aperture Through-the-Wall Radar Imaging

A Back-Projection Algorithm to Stepped-Frequency Synthetic A...

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2007 Asian and Pacific Conference on Synthetic Aperture Radar(APSAR 2007)

作者： Guolong Cui,Lingjiang Kong,Jianyu Yang University of Electronic Science and Technology of China(UESTC)

back-projection imaging algorithm is widely used in through-the-wall and GPR imaging because of the high image quality and being compensated *** this paper,the author will introduce the back-projection algorithm to the stepped-frequency through-the-wall radar and put forward the time-minimization method to eliminate the wall's effects,such as refraction,changing in speed and *** of concept is provided using real data collected in a laboratory *** results show that the BP algorithm can outputs a high quality image and the time-minimization method can eliminate the wall's effect very well.

关键词： stepped-frequency through-the-wall radar back-projection algorithm the time-minimization method

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An Improved back-projection algorithm for Magnetic Induction Tomography Image Reconstruction

An Improved Back-projection Algorithm for Magnetic Induction...

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2012 International Conference on Biomaterial and Bioengineering(ICBB 2012)

作者： Li Ke Xiao Lin Qiang Du Institute of Biomedical and Electromagnetic Engineering Shenyang University of Technology

Magnetic induction tomography(MIT) acted as a contactless and non-invasive medical imaging technology has aroused wide concern, while a large amount of calculation and a series of convergence problems in the solution of the inverse problem become technical difficulties for MIT. In order to solve these problems, an improved back-projection image reconstruction algorithm based on the magnetic field lines distribution is presented in this paper. Firstly, the eddy current problem of MIT was solved by the finite element method to obtain the magnetic field distribution. Secondly, the back-projection areas were divided according to the magnetic field lines distribution in the homogeneous field. Finally, image reconstruction was realized by projecting the phase shifts back along the corresponding projection area. The reconstruction results for perturbations with different conductivities appearing at different locations reveal that the improved back-projection algorithm for MIT owning the character of high speed performs well in reflecting location and shape information of the perturbation.

关键词： Magnetic Induction Tomography back-projection algorithm Image Reconstruction

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A near-field back-projection algorithm for wall penetrating SAR

A near-field back-projection algorithm for wall penetrating ...

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IET International Radar Conference 2015

作者： Wei Liu Wei Wei Meng Zheng Yin Xiang Zegang Ding Beijing Key Laboratory of Embedded Real-time Information Processing Technology Beijing Institute of Technology No. 203 Research Institute of China Ordance Industries Xi'an Shaanxi 710065 China

ISBN: (纸本)9781510822023

We are going to develop a handheld wall penetrating SAR (WPSAR) to investigate the small shallowly buried objects such as thin wires, cables and so on. The WPSAR will be working very close to the wall surface, and the objects of interest sometimes buried inside the induced near-filed region of the probe. As a result, the traditional far-field SAR imaging algorithm cannot be used. Thus, a useful near-field back-projection algorithm is investigated in this paper, which backprojects the probe's aperture field into the wall, instead of backprojecting the echo signal along the wave propagation track as it is done in the traditional BP. A full wave simulation data given by CST is used to validate our algorithm. The result shows that the proposed near-field BP algorithm gives a correct imaging result while the traditional one fails.

关键词： back-projection algorithm Synthetic aperture radar Near-field imaging Ground penetrating radar Synthetic aperture radar ground penetrating radar projection algorithms near-field algorithms wall surface wall simulated data Rescue Specific absorption rate SAFETY ANALYSIS REPORTS Probes CONDENSATE STORAGE TANK

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Implementing a back-projection Tomographic Reconstruction algorithm Using a Fan-Shaped Beam

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RUSSIAN JOURNAL OF NONDESTRUCTIVE TESTING 2017年第5期53卷 387-392页

作者： Ozdiev, A. Kh. Kryuchkov, Yu. Yu. Tomsk Polytech Univ Phys Tech Inst Tomsk 634050 Russia

A back-projection tomographic reconstruction algorithm using a fan-shaped beam is considered. The freeware that implements the method of back projections is mainly applicable only in the case of parallel radiation. Distinctions in how this approach is applied when using parallel and fan-shaped beams are described in part that is related to the geometry of an experiment. The implementation of the algorithm with allowance for the peculiarities of reconstruction with a divergent beam is presented as a flow chart. The results provided in the paper demonstrate the working capacity of the algorithm.

关键词： X-ray tomography fan-shaped beam reconstruction back-projection algorithm

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back-projection Imaging for Synthetic Aperture Radar with Topography Occlusion

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REMOTE SENSING 2023年第3期15卷 726-726页

作者： Chen, Zhanye Zeng, Zhiqiang Fu, Dongning Huang, Yan Li, Qiang Zhang, Xin Wan, Jun Chongqing Univ Sch Microelect & Commun Engn Chongqing 400044 Peoples R China Chongqing Univ Chongqing Key Lab Space Informat Network & Intelli Chongqing 400044 Peoples R China Hwa Create Technol Cop Ltd Beijing 100193 Peoples R China HWA NCUT Radar RF Simulat Lab Beijing 100114 Peoples R China Southeast Univ Sch Informat Sci & Engn State Key Lab Millimeter Waves Nanjing 210096 Peoples R China Xidian Univ Hangzhou Inst Technol Hangzhou 311200 Peoples R China

When synthetic aperture radar (SAR) is conducting remote sensing or terrain mapping, its radar beam is inevitably occluded by the variations in the under-test topography. Although back-projection algorithm (BPA) can theoretically directly solve the imaging problems of topography variations that most current SAR imaging algorithms cannot handle, these BPAs only solve the phase focusing of SAR echo signal, and do not consider the mismatch of SAR imaging results caused by topography occlusion. To solve the mis-imaging issue of the occluded area generated by BPA under the case of topography variation, a topography-based BPA (Topo-BPA) is proposed in this paper. Firstly, a new beam occlusion judgment algorithm based on spherical wave assumption is proposed, and its core is depression angle interpolation and depression angle updating. Then, the proposed Topo-BPA embeds the proposed beam occlusion judgment algorithm before the classical BPA, which not only did not reduce the focus depth of BPA, but improved the imaging accuracy of classical BPA. Finally, numerical experiments have demonstrated the superiority of the Topo-BPA's performance in comparison with classical BPA.

关键词： back-projection algorithm synthetic aperture radar topography variation beam occlusion

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