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In this study, we adopt a criterion of Barker code to generate a high-resolution image from sparse flight samples to establish a three-dimensional (3-D) imaging model of airborne array SAR. Under the condition of motion error, we utilize the Modified Uniformly Redundant Arrays (MURA) modulation and 3-D Back Projection (BP) algorithm to obtain 3-D complex image pairs under each flight. Based on interferometry and Compressed Sensing (CS) in frequency domain, the array deformation error compensation is realized. The phases of 3-D complex image formed by the echo corresponding to negative MURA modulation are referred to perform phase compensation on each single-pass complex image to restore the image phase relation of each flight. Coherent accumulation of each complex image is implemented to realize high-resolution 3-D imaging under sparse flight sampling. Simulation analysis and experimental data verify the feasibility of the proposed method.

Copyright of Laser Technology is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

CurviLinear SAR (CLSAR) is increasingly attracting considerable interest in the field of radar remote sensing. Various methods of 3-D target feature extraction and aperture design have been proposed, and these methods are classified in this paper. The basic theories of these methods are systematically studied and compared, and their advantages and disadvantages are summarized. Moreover, the main 3-D target feature extraction and aperture methods are described. Finally, the future research fields of CLSAR are proposed.

To realize perception of local lunar surface under the condition of relative stationary before soft landing during moon discovery, a novel 3-D imaging method is proposed. The method is based on range high-resolution in altitude dimensional and 2-D receiving digital beam forming to radar scene floor. The outstanding feature is this method can realize 3-D imaging without relative motion between radar and target. According to imaging principle, the transmitting waveforms, antenna shape and size has been researched and designed; the choosing of imaging height and stepping size for scene scan were also discussed; the whole imaging processing flow was given and has been simulated using computer. Simulation results indicate that it can obtain 3-D coordinates of strong scattering centers accurately and reconstruct 3-D image of scene successfully. [ABSTRACT FROM AUTHOR]

In order to accurately recover the complete shape of the measured object with partial occlusion, a system for light field 3-D imaging based on multi-line structured light marking was proposed and a structured light field 3-D imaging method based on the Hough transform was proposed for the image processing problem in this system. The extracted sub-pixel fringe center coordinates were used to Hough transform, then the voting distribution in the Hough parameter space was analyzed, and adaptive range voting and adaptive window strategies were designed. Consequently, the parameters of multiple straight lines in the epipolar plane image can be accurately determined by the proposed method, which does not need to encode the fringe level. The experimental results show that the mean deviation and standard deviation of the fitted plane are 0.0096 mm and 0.0074 mm respectively. The complete shape of measured object is accurately obtained, which utilities the occlusion of different sub-aperture images is inconsistent in light field imaging. The result is helpful for solving the occlusion problem in the 3-D measurement process, and this work provides a reference for the measurement method to obtain complete and efficient 3-D data. [ABSTRACT FROM AUTHOR]

Conventional Synthetic Aperture Radar (SAR) can only obtain two-dimensional (2-D) azimuth-range images without accurately reflecting the three-Dimensional (3-D) scattering structure information of the targets. However, SAR Tomography (TomoSAR) is a multi-baseline interferometric measurement mode that extends the synthetic aperture principle into the elevation direction, making it possible to recover the true height of the target, thereby achieving 3-D imaging. Moreover, Differential SAR Tomography (D-TomoSAR) extends the synthetic aperture principle into the elevation and time directions simultaneously. Thus, it can obtain the target 3-D scattering structure along with the deformation speed of the observed target. GaoFen-3 (GF-3) is the first C-band multi-polarization 1 m resolution SAR satellite of China. It has several advantages, such as high-resolution, large swath width, and multiple imaging modes, which are crucial to the development of a high-resolution earth observation technology for China. Presently, GF-3 data are mainly used in the image processing field, such as target identification. However, the phase information of the SAR images is not yet fully utilized. Moreover, because of the high-dimensional imaging ability that was overlooked at the beginning of designing the system, existing SAR images acquired by GF-3 have spatial and temporal de-coherence problems. Thus, it is difficult to use the images in further interference series processing. To solve the above problems, this study achieved 3-D and four-Dimensional (4-D) imaging of buildings around Yanqi Lake, in Beijing, based on the data of seven SAR complex images. We obtained the 3-D scattering structure information of buildings and achieved millimeter-level high-precision monitoring of building deformation. The preliminary experimental results demonstrate the application potential of GF-3 SAR data and provide a technical support for the subsequent further application of the GF-3 SAR satellite in urban sensing and monitoring.

Copyright of Systems Engineering & Electronics is the property of Journal of Systems Engineering & Electronics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Signal Processing is the property of Journal of Signal Processing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper proposes a three-dimensional tomographic SAR imaging method based on a combined sparse and low-rank structures. The traditional Compressed Sensing (CS) based tomographic SAR imaging methods only utilize the sparse representation and reconstruct along the elevation axis of a given azimuth-distance unit. Considering that the target distributions in cities, forests, and other cases are relatively similar, the elevation backscattering patterns of adjacent azimuth-range cells (pixels) are expected to be highly correlated. The proposed method introduces the Karhunen-Loeve transform to characterize the low-rank structures of the elevation of the target areas and constructs a tomographic SAR imaging model that combines sparse and low-rank structures. The ADMM algorithm is applied to solve the tomographic SAR imaging model, the complex original optimization problem is decomposed into several relatively simple sub-problems, and the tomographic SAR imaging results are obtained by the alternate projection of optimization variables. This method improves the reconstruction accuracy in the case of a few interferograms or channels and has better imaging performance. Simulations and real data experiments show that the reconstruction method can effectively separate the scatterers and ensure the accuracy of the reconstruction energy, maintain a good imaging performance under the condition of reducing the number of interferograms or channels, and effectively suppress the artifacts.

Array Synthetic Aperture Radar (ASAR) system radar imaging field has gained attention because of its three-dimensional (3-D) imaging ability. A novel Circular Array SAR (CASAR) system is employed for 3-D high-resolution radar imaging to overcome the drawbacks exhibited by linear array SAR in high-resolution imaging and by circular SAR in side-lobe suppression. Point Spread Function (PSF) model based on the CASAR system is derived, and the advantages of the new configuration of the circular array in 3-D imaging are theoretically analyzed. Prototype CASAR experimental system is built on the basis of the abovementioned analysis. PSF simulation experiments and outdoor 3-D CASAR imaging experiments under outdoor conditions are performed to verify performance of the CASAR system in 3-D SAR imaging. Compared imaging results acquired using linear array SAR, circular SAR, and CASAR system proves that the CASAR system has highresolution 3-D SAR images and demonstrates effective side-lobe suppression capability.

The size and the shape of brain tissue offer lots of information for clinical diagnosis and treatment. The commercial imaging systems, such as x-ray computer tomography (CT) and magnetic resonant image (MRI), always display only two dimensional (2-D) image, which makes quantitative diagnosis of the variation of brain tissue very difficult. Furthermore, some tissue may be connected through little vessels, which is also difficult to identify using discrete 2-D image. In this study, we processed CT image data using an general purpose IBM personal computer. A new three dimensional (3-D) recursive tracing algorithm was proposed. This new algorithm can automatically extract the image of brain tissue in each 2-D image. The information obtained was therefore used to reconstruct 3-D image. This system allows user to observe 3-D size and shape of brain tissue from arbitrary view. Such 3-D image can also be used to calculate the volume of tissue. Using overlay projecting method, it can display skin, bone, brain tissue and gray material at the same time. Such display method accurately shows the relative position of each tissue and offer physicians important information for diagnosis and treatment.

The concept of Geosynchronous Circular SAR (Geo-CSAR) is introduced in this paper. With the design of the geosynchronous orbit parameters, a near-circular satellite sub-track could be formed to enable the staring imaging mode, which supports the advanced applications for wide-field and 3-D information acquisition under long-term consistent observation. This paper also analyzes Geo-CSAR's imaging formation capabilities, and concludes its attractive advantages over low-earth orbit spaceborne SAR in terms of instantaneous coverage, consistent observing area, 3-D positioning accuracy and etc.. Encouraging expectations for Geo-CSAR thus could be positively predicted in military investigation and disaster monitoring management applications.

Copyright of Journal of Remote Sensing is the property of Editorial Office of Journal of Remote Sensing & Science Publishing Co. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Laser Technology is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Signal Processing is the property of Journal of Signal Processing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Signal Processing is the property of Journal of Signal Processing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Near-field 3-D imaging based on a scanning array is an important application of Synthetic Aperture Radar (SAR) 3-D imaging technology for civil use. Compared with Single-Input-Single-Output (SISO) arrays, a Multi-Input-Multi-Output (MIMO) scanning system is a special imaging method characterized by high imaging quality, high array efficiency, loose requirements for antenna spacing and low cost. In this paper, two imaging regimes, namely, MIMO-planar scanning and MIMO cylindrical scanning, are described in terms of signal models, imaging algorithms, experimental systems, and imaging results. The results show the great application potential of the imaging technology in various scenarios.

Using azimuth beam steering, space-borne Synthetic Aperture Radar (SAR) can observe from multiple azimuth angle in single pass. During multiple azimuth angle observation, the satellite orbit is equivalent to long three-dimensional (3-D) curvilinear array, which has the potential for 3-D imaging. Sampling by space-borne multiple azimuth angle SAR is sparse in height dimension, which makes unambiguous 3-D imaging by 3-D fast Fourier transform infeasible. Besides, the complex relationship between the targets’projection in multi-angle SAR images and the height error is difficult to determine. To overcome this limitation, in this paper, we present a 3-D imaging method based on joint multiple azimuth angle Doppler frequency rate estimation. First, a relationship is proposed between the height error and Doppler frequency rate at different azimuth angle. Then, the Doppler frequency modulation rate error is estimated by Map Drift (MD) technique. Next, the height estimation results of different azimuth angle are combined to improve the estimation accuracy. From the estimated height and the target location in the SAR images, 3-D geometric information is retrieved and 3-D imaging is achieved. Our simulation experiments validate that the height estimation can achieve an accuracy of few meters with the proposed method.

To study the PET imaging performance of cross-strip cadmium zinc telluride detector with a size of 16.4 mm×16.4 mm×5 mm, which can determine the 3-D position information of 511 keV gamma photons. The 32 electrodes of the detector are all read out using charge sensitive preamplifiers and filter amplification modules, and then input high-speed analog-to-digital converters to sample the data, and obtain the full pulse shape of the signal in the detector, and use the ADC built-in FPGA to perform the online signal processing, digital processing such as peak finding and filtering. The energy resolution of the CZT detector for 511 keV gamma photons is 6.35%. According to the electrode structure of the CZT detector, 3-D position coordinate calculation formulas for the interaction of gamma photons can be obtained. The CZT detector realizes a 3-D imaging function with a sub-millimeter resolution.

Synthetic Aperture Radar (SAR) Tomography (TomoSAR) is a novel technique that enables three-Dimensional (3-D) imaging using multi-baseline two-Dimensional (2-D) data. The essence of TomoSAR is actually to solve a one-dimensional spectral estimation problem. Compressed Sensing-based (CS) algorithm can retrieve solutions with only a few non-uniform acquisitions and has gradually become the main imaging method. In the conventional processing flow of CS algorithms, the continuous elevation direction is divided into a pre-set grid, and the targets are assumed to be exactly on the grid. \begin{document}$ {{L}}_{1} $\end{document} minimization has been proven to be effective in TomoSAR imaging. In the conventional processing flow, the continuous elevation axis is divided into fixed grids, and scatters are assumed to be exactly on the pre-set grid. However, this hypothesis is generally untenable, and will lead to a problem called “Basis Mismatch”, which is rarely discussed in TomoSAR. In this letter, we first discuss the model of Off-grid TomoSAR, and then propose an addictive perturbation model to compensate for the errors caused by the grid effect. We utilize the local optimization thresholding algorithm to solve the complex-valued \begin{document}$ {{L}}_{1} $\end{document} minimization problem of TomoSAR. We conducted experiments both on simulation data and actual airborne flight data. Our simulation results indicate that the proposed method can estimate a more accurate position of scatters, which leads to better original signal recovery. The reconstruction results of actual data verify that the impact of grid mismatch can be mostly eliminated.

PURPOSE: To evaluate the clinical usefulness of spiral 3-D CT reconstruction for maxillary impacted teeth. METHODS: Spiral CT was performed in 47 patients whose maxillary impacted teeth couldn't be judged clearly through the panoramic radiograph and occlusal film. 3-D reconstruction, including MIP (maximum intensity projection) and MPR (multiplanar reconstructions) was made to display the impacted teeth's shape, location and its relationship with adjacent teeth. RESULTS: There were 67 maxillary impacted teeth in 47 patients. Spiral 3-D CT could clearly demonstrate the dental image including crown, root, neck and root bifurcation, and 3-D imaging could clearly display the maxilla anatomy and the dental structure.CONCLUSION: Spiral CT 3-D reconstruction is a useful technique to display three- dimensional configuration of teeth.Three dimensional reconstruction is an accurate and effective method to localize impacted teeth before orthodontic treatment. Supported by Key Science and Technology Research Project of Shandong Province (Grant No. 2006GG2202031) and Key Science and Technology Research Project of Dongying City (2006-24). [ABSTRACT FROM AUTHOR]

To improve the cross-range resolution of three-dimensional (3-D) images obtained along the direction of movement by Multiple-Input Mmultiple-Output (MIMO) radar, a novel MIMO-ISAR 3-D imaging method that combines multi-snapshot images is proposed. This method integrates multiple single-snapshot 3-D images acquired by a planar antenna array during a specific period of observation and extracts the peak slice along the linear fitting direction of the scatterers to construct a new 3-D image. The simulation results demonstrated that the proposed method significantly improves the cross-range resolution of the imaging results along the direction of movement compared with other methods based on single-snapshot 3-D images. Additionally, compared with the classical MIMO-ISAR method based on rearrangement and interpolation, this method is suitable for both fast-moving and slow-moving targets. Moreover, the imaging results are well focused and the side lobes along the direction of movement are effectively suppressed.

Linear Array Synthetic Aperture Radar (LASAR) is a novel and promising radar imaging technique. In recent years, Compressed Sensing (CS) sparse recovery has been a research focus for high-resolution three-Dimensional (3-D) LASAR imaging. Compared with the traditional two-Dimensional (2-D) SAR imaging, LASAR suffers from many problems, including under-sampling data and multi-dimensional and higher-order phase errors due to its sparse Linear Array Antenna (LAA) and the joint 2-D motions of the platform and LAA. The conventional autofocusing methods of 2-D SAR may be not suitable for CS-based LASAR 3-D sparse autofocusing. To address the multi-dimensional and higher-order phase errors in LASAR 3-D imaging with respect to under-sampling data, in this paper, we propose a sparse autofocusing algorithm based on semidefinite programming for CS-based LASAR imaging. First, by combining CS-based imaging theory, image maximum sharpness, and the minimum square error principle, we construct a LASAR phase-error estimation model based on under-sampled data. Next, we use semi-definite programming relaxation to estimate the phase errors. Lastly, we employ an iterated approximation method to improve the precision of the phase-error estimation and achieve the final CS-based LASAR autofocusing. To further improve the efficiency of the algorithm, we select only the dominant scattering areas for LASAR phase-error estimation. We present our simulation and experimental results to confirm the effectiveness of out proposed algorithm.

3D cone beam computed tomography (CBCT) images offer a unique and new appreciation of the anatomical structures and underlying anomalies not possible with conventional radiographs. However, in almost all aspects of CBCT imaging, from utilization to application, inherent limitations and pitfalls exist. Importantly, these inherent limitations and pitfalls have practical implications which need to be addressed before the potential of this technology can be fully realized. The purpose of this review was to explore the current limitations and pitfalls associated with CBCT imaging to allow for better and more accurate understanding of the possibilities this imaging modality could offer, particularly pertaining to 3D cephalometry. [ABSTRACT FROM AUTHOR]

Objective: To explore the application of imaging techniques in determining the death cause and injury manner., Methods: One case due to high fall was fully examined using multi-slice spiral computed tomography (MSCT), 3-D imaging creation and magnetic resonance imaging (MRI). The systemic and detailed autopsy was subsequently performed to compare with the results from imaging studies. The advantages and disadvantages of autopsy and imaging studies were then analyzed., Results: Most of the important information such as trauma, fracture and hemorrhage could be obtained by imaging techniques. Furthermore, imaging methods can predict injuries in internal body before autopsy and be minimal or non-invasive to the cadaver. However, the imaging techniques probably also can not find some details in comparison to autopsy in forensic practice and need to improve in their future application., Conclusion: Application of imaging techniques can be used as the guidance and complimentary for the forensic autopsy in the identification of injury manner. In addition, the application can even be used to replace autopsy in some special circumstances.

Purpose: To evaluate the clinical usefulness of spiral 3-D CT reconstruction for maxillary impacted teeth., Methods: Spiral CT was performed in 47 patients whose maxillary impacted teeth couldn't be judged clearly through the panoramic radiograph and occlusal film. 3-D reconstruction, including MIP (maximum intensity projection) and MPR (multiplanar reconstructions) was made to display the impacted teeth's shape, location and its relationship with adjacent teeth., Results: There were 67 maxillary impacted teeth in 47 patients. Spiral 3-D CT could clearly demonstrate the dental image including crown, root, neck and root bifurcation, and 3-D imaging could clearly display the maxilla anatomy and the dental structure., Conclusion: Spiral CT 3-D reconstruction is a useful technique to display three-dimensional configuration of teeth.Three dimensional reconstruction is an accurate and effective method to localize impacted teeth before orthodontic treatment.

Confocal scanning microscopy is a new technique which can obtain the 3-D images of samples by using scanning and computer processing. It has been widely used in biomedical fields owing to its advantages such as high resolution and 3-D imaging. In this paper, we analyze the principle and research development of confocal scanning microscopies, and illustrate its advantages by comparing it with other microscopies.

Background: To apply spiral CT angiography( SCTA) as imaging method of pulmonary angiography and study the imaging findings of cancerous invasion of central pulmonary artery (CICPA) in lung cancer patients by means of spiral CT pulmonary angiography (SCTPA) ., Methods: Thirty patients with central type of lung cancer proved by bronchoscopy biopsy or surgery underwent SCTPA, and 30 cases who had negative results on conventional CT as control. Technic parameters of SCTPA applied for both groups were as follows: contrast medium injection rate of 3-4ml/ s, collimation of 3mm, pitch of 1. 5, reconstruction interval of 1. 2 mm. The CT manifestations of vessel course and lumen of central pulmonary artery(CPA) were observed and the enhancement intensity of CICPA segment wasmeasured by 3-D imaging of CTA., Results: The changes of vessel course were found in 18 cases( 60%) . The direction of displacement of CPA was different depending on predominant site of the mass and the pathway of CICPA. Centripetal or eccentric stenosis of CPA lumen in various degree with rigid and smooth contour was visualized in 26 cases( 86. 7%) . Decreased enhancement intensity of CPA was significantly shown in cases whose CPA lumen severely narrowed ( P < 0. 05) , and not distinct while stenosis of CPA lumen wasmild tomoderate degree ( P > 0. 05) ., Conclusions: The direct CT signs of CICPA in lung cancer by SCTPA in this study include displacement of vessel course, stenosis of lumen and decreased intensity of contrast enhancement of CPA. SCTPA is a significant complement to conventional CT in diagnosis of CICPA in lung cancer.