scholarly journals Three-Dimensional Interferometric ISAR Imaging Algorithm Based on Cross Coherence Processing

Sensors ◽  
2021 ◽  
Vol 21 (15) ◽  
pp. 5073
Author(s):  
Qian Lv ◽  
Shaozhe Zhang
Keyword(s):  
3D Imaging ◽  
High Efficiency ◽  
Imaging System ◽  
Computational Cost ◽  
Three Dimensional ◽  
Reconstruction Algorithm ◽  
Image Plane ◽  
Interferometric Phase ◽  
Isar Imaging ◽  
Reflectivity Function

Interferometric inverse synthetic aperture radar (InISAR) has received significant attention in three-dimensional (3D) imaging due to its applications in target classification and recognition. The traditional two-dimensional (2D) ISAR image can be interpreted as a filtered projection of a 3D target’s reflectivity function onto an image plane. Such a plane usually depends on unknown radar-target geometry and dynamics, which results in difficulty interpreting an ISAR image. Using the L-shape InISAR imaging system, this paper proposes a novel 3D target reconstruction algorithm based on Dechirp processing and 2D interferometric ISAR imaging, which can jointly estimate the effective rotation vector and the height of scattering center. In order to consider only the areas of the target with meaningful interferometric phase and mitigate the effects of noise and sidelobes, a special cross-channel coherence-based detector (C3D) is introduced. Compared to the multichannel CLEAN technique, advantages of the C3D include the following: (1) the computational cost is lower without complex iteration and (2) the proposed method, which can avoid propagating errors, is more suitable for a target with multi-scattering points. Moreover, misregistration and its influence on target reconstruction are quantitatively discussed. Theoretical analysis and numerical simulations confirm the suitability of the algorithm for 3D imaging of multi-scattering point targets with high efficiency and demonstrate the reliability and effectiveness of the proposed method in the presence of noise.

scholarly journals Three-dimensional imaging of hold baggage for airport security

2014 ◽  
Vol XL-5 ◽  
pp. 331-336
Author(s):  
S. Kolokytha ◽  
R. Speller ◽  
S. Robson
Keyword(s):  
3D Imaging ◽  
Imaging System ◽  
Tomographic Reconstruction ◽  
Three Dimensional ◽  
Handling Time ◽  
Cost Effective ◽  
Airport Security ◽  
X Ray ◽  
Common System ◽  
Close Range

This study describes a cost-effective check-in baggage screening system, based on "on-belt tomosynthesis" (ObT) and close-range photogrammetry, that is designed to address the limitations of the most common system used, conventional projection radiography. The latter's limitations can lead to loss of information and an increase in baggage handling time, as baggage is manually searched or screened with more advanced systems. This project proposes a system that overcomes such limitations creating a cost-effective automated pseudo-3D imaging system, by combining x-ray and optical imaging to form digital tomograms. Tomographic reconstruction requires a knowledge of the change in geometry between multiple x-ray views of a common object. This is uniquely achieved using a close range photogrammetric system based on a small network of web-cameras. This paper presents the recent developments of the ObT system and describes recent findings of the photogrammetric system implementation. Based on these positive results, future work on the advancement of the ObT system as a cost-effective pseudo-3D imaging of hold baggage for airport security is proposed.

scholarly journals A Microwave Three-Dimensional Imaging Method Based on Optimal Wave Spectrum Reconstruction

Sensors ◽  
2020 ◽  
Vol 20 (24) ◽  
pp. 7306
Author(s):  
Yan Zhang ◽  
Baoping Wang ◽  
Yang Fang ◽  
Zuxun Song
Keyword(s):  
3D Imaging ◽  
Imaging System ◽  
Wave Spectrum ◽  
Sampling Rate ◽  
Three Dimensional ◽  
Imaging Method ◽  
Data Sampling ◽  
Spectrum Reconstruction ◽  
Memory Space ◽  
Target Wave

Limited by the Shannon–Nyquist sampling law, the number of antenna elements and echo signal data of the traditional microwave three-dimensional (3D) imaging system are extremely high. Compressed sensing imaging methods based on sparse representation of target scene can reduce the data sampling rate, but the dictionary matrix of these methods takes a lot of memory, and the imaging has poor quality for continuously distributed targets. For the above problems, a microwave 3D imaging method based on optimal wave spectrum reconstruction and optimization with target reflectance gradient is proposed in this paper. Based on the analysis of the spatial distribution characteristics of the target echo in the frequency domain, this method constructs an orthogonal projection reconstruction model for the wavefront to realize the optimal reconstruction of the target wave spectrum. Then, the inverse Fourier transform of the optimal target wave spectrum is optimized according to the law of the target reflectance gradient distribution. The proposed method has the advantages of less memory space and less computation time. What is more, the method has a better imaging quality for the continuously distributed target. The computer simulation experiment and microwave anechoic chamber measurement experiment verify the effectiveness of the proposed method.

scholarly journals Application of Three-Dimensional Imaging to the Intestinal Crypt Organoids and Biopsied Intestinal Tissues

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Yun Chen ◽  
Ya-Hui Tsai ◽  
Yuan-An Liu ◽  
Shih-Hua Lee ◽  
Sheng-Hong Tseng ◽  
...  
Keyword(s):  
3D Imaging ◽  
Imaging System ◽  
3D Structure ◽  
Three Dimensional ◽  
Spatial Relationship ◽  
Intestinal Transplantation ◽  
Muscle Layer ◽  
3D Images ◽  
Nerve Network ◽  
Transplant Patients

Two-dimensional (2D) histopathology is the standard analytical method for intestinal biopsied tissues; however, the role of 3-dimensional (3D) imaging system in the analysis of the intestinal tissues is unclear. The 3D structure of the crypt organoids from the intestinal stem cell culture and intestinal tissues from the donors and recipients after intestinal transplantation was observed using a 3D imaging system and compared with 2D histopathology and immunohistochemistry. The crypt organoids and intestinal tissues showed well-defined 3D structures. The 3D images of the intestinal tissues with acute rejection revealed absence of villi and few crypts, which were consistent with the histopathological features. In the intestinal transplant for megacystis microcolon intestinal hypoperistalsis syndrome, the donor’s intestinal tissues had well-developed nerve networks and interstitial cells of Cajal (ICCs) in the muscle layer, while the recipient’s intestinal tissues had distorted nerve network and the ICCs were few and sparsely distributed, relative to those of the donor. The 3D images showed a clear spatial relationship between the microstructures of the small bowel and the features of graft rejection. In conclusion, integration of the 3D imaging and 2D histopathology provided a global view of the intestinal tissues from the transplant patients.

Validation of a Vision-Based, Three-Dimensional Facial Imaging System

2003 ◽  
Vol 40 (5) ◽  
pp. 523-529 ◽  
Author(s):  
A. Ayoub ◽  
A. Garrahy ◽  
C. Hood ◽  
J. White ◽  
M. Bock ◽  
...  
Keyword(s):  
3D Imaging ◽  
Cleft Lip ◽  
Imaging System ◽  
Three Dimensional ◽  
Procrustes Analysis ◽  
Facial Morphology ◽  
3D Images ◽  
Registration Errors ◽  
Measuring Machine ◽  
Full Face

Objective The aim of this study was to assess the accuracy of a newly developed three-dimensional (3D) imaging system in recording facial morphology. Methods Twenty-one infants with cleft lip each had a full-face alginate impression taken at the time of primary lip repair, and a stone cast was constructed from each impression. Five anthropometric points were marked on each cast. Each cast was digitized, and the 3D co-ordinates of the five points were obtained using a co-ordinate measuring machine (CMM, Ferranti) of documented accuracy (9.53 μm). Each cast was scanned in four positions using a computerized stereophotogrammetry (C3D) system. The five points were located on the 3D images, and their 3D co-ordinates were extracted by three operators. The co-ordinate systems produced by C3D were aligned, via translation and rotation, to match the CMM co-ordinate system using partial ordinary procrustes analysis. The displacements of the adjusted C3D co-ordinates from the reference co-ordinates were then measured. Three different types of errors were identified: operator, system, and registration errors. Results Operator error was within 0.2 mm of the true co-ordinates of the landmarks. C3D was accurate within 0.4 mm. The average displacement of points over the 21 casts at four positions for the three operators was 0.79 mm (median 0.68). Conclusions The presented 3D imaging system is reliable in recording facial deformity and could be utilized in recording cleft deformities and measuring the changes following surgery

scholarly journals Scanning acoustic microscopy for material evaluation

2020 ◽  
Vol 50 (1) ◽  
Author(s):  
Hyunung Yu
Keyword(s):  
Cross Sections ◽  
High Efficiency ◽  
Three Dimensional ◽  
High Sensitivity ◽  
Reconstruction Algorithm ◽  
Acoustic Microscopy ◽  
Light Sources ◽  
Scanning Acoustic Microscopy ◽  
Nonlinear Properties ◽  
Additional Information

Abstract Scanning acoustic microscopy (SAM) or Acoustic Micro Imaging (AMI) is a powerful, non-destructive technique that can detect hidden defects in elastic and biological samples as well as non-transparent hard materials. By monitoring the internal features of a sample in three-dimensional integration, this technique can efficiently find physical defects such as cracks, voids, and delamination with high sensitivity. In recent years, advanced techniques such as ultrasound impedance microscopy, ultrasound speed microscopy, and scanning acoustic gigahertz microscopy have been developed for applications in industries and in the medical field to provide additional information on the internal stress, viscoelastic, and anisotropic, or nonlinear properties. X-ray, magnetic resonance, and infrared techniques are the other competitive and widely used methods. However, they have their own advantages and limitations owing to their inherent properties such as different light sources and sensors. This paper provides an overview of the principle of SAM and presents a few results to demonstrate the applications of modern acoustic imaging technology. A variety of inspection modes, such as vertical, horizontal, and diagonal cross-sections have been presented by employing the focus pathway and image reconstruction algorithm. Images have been reconstructed from the reflected echoes resulting from the change in the acoustic impedance at the interface of the material layers or defects. The results described in this paper indicate that the novel acoustic technology can expand the scope of SAM as a versatile diagnostic tool requiring less time and having a high efficiency.

scholarly journals Squint Model InISAR Imaging Method Based on Reference Interferometric Phase Construction and Coordinate Transformation

2021 ◽  
Vol 13 (11) ◽  
pp. 2224
Author(s):  
Yu Li ◽  
Yunhua Zhang ◽  
Xiao Dong
Keyword(s):  
Coordinate Transformation ◽  
Cross Correlation ◽  
Three Dimensional ◽  
Image Distortion ◽  
Imaging Method ◽  
Phase Ambiguity ◽  
Correlation Algorithm ◽  
Interferometric Phase ◽  
Isar Imaging

The imaging quality of InISAR under squint geometry can be greatly degraded due to the serious interferometric phase ambiguity (InPhaA) and thus result in image distortion problems. Aiming to solve these problems, a three-dimensional InISAR (3D ISAR) imaging method based on reference InPhas construction and coordinate transformation is presented in this paper. First, the target’s 3D coarse location is obtained by the cross-correlation algorithm, and a relatively stronger scatterer is taken as the reference scatterer to construct the reference interferometric phases (InPhas) so as to remove the InPhaA and restore the real InPhas. The selected scatterer needs not to be exactly in the center of the coarsely located target. Then, the image distortion is corrected by coordinate transformation, and finally the 3D coordinates of the target can be accurately estimated. Both simulation and practical experiment results validate the effectiveness of the method.

scholarly journals High-dynamic range compressive spectral imaging by grayscale coded aperture adaptive filtering

2015 ◽  
Vol 35 (3) ◽  
pp. 53-60 ◽  
Author(s):  
Nelson Eduardo Diaz ◽  
Hoover Fabian Rueda Chacon ◽  
Henry Arguello Fuentes
Keyword(s):  
Dynamic Range ◽  
Imaging System ◽  
Three Dimensional ◽  
Spectral Imaging ◽  
Reconstruction Algorithm ◽  
High Dynamic Range ◽  
Data Cube ◽  
Coded Aperture ◽  
Coded Apertures

<p class="p1">The coded aperture snapshot spectral imaging system (CASSI) is an imaging architecture which senses the three dimensional informa-tion of a scene with two dimensional (2D) focal plane array (FPA) coded projection measurements. A reconstruction algorithm takes advantage of the compressive measurements sparsity to recover the underlying 3D data cube. Traditionally, CASSI uses block-un-block coded apertures (BCA) to spatially modulate the light. In CASSI the quality of the reconstructed images depends on the design of these coded apertures and the FPA dynamic range. This work presents a new CASSI architecture based on grayscaled coded apertu-res (GCA) which reduce the FPA saturation and increase the dynamic range of the reconstructed images. The set of GCA is calculated in a real-time adaptive manner exploiting the information from the FPA compressive measurements. Extensive simulations show the attained improvement in the quality of the reconstructed images when GCA are employed.  In addition, a comparison between traditional coded apertures and GCA is realized with respect to noise tolerance.</p>

scholarly journals Accuracy and Precision of Three-dimensional Imaging System of Children’s Facial Soft Tissue

2020 ◽  
Vol 47 (1) ◽  
pp. 17-24
Author(s):  
Kyunghwa Choi ◽  
Misun Kim ◽  
Koeun Lee ◽  
Okhyung Nam ◽  
Hyo-seol Lee ◽  
...  
Keyword(s):  
Soft Tissue ◽  
3D Imaging ◽  
Imaging System ◽  
Three Dimensional ◽  
Facial Growth ◽  
3D Scanner ◽  
Facial Soft Tissue ◽  
Linear Measurements ◽  
Accuracy And Precision ◽  
3D Photogrammetry

The purpose of this study was to evaluate the accuracy and precision of the three-dimensional (3D) imaging system of children’s facial soft tissue by comparing linear measurements. The subjects of the study were 15 children between the ages of 7 and 12. Twenty-three landmarks were pointed on the face of each subject and 16 linear measurements were directly obtained 2 times using an electronic caliper. Two sets of 3D facial images were made by the 3D scanner. The same 16 measurements were obtained on each 3D image. In the accuracy test, the total average difference was 0.9 mm. The precision of 3D photogrammetry was almost equivalent to that of direct measurement. Thus, 3D photogrammetry by the 3D scanner in children had sufficient accuracy and precision to be used in clinical setting. However, the 3D imaging system requires the subject’s compliance for exact images. If the clinicians provide specific instructions to children while obtaining 3D images, the 3D device is useful for investigating children’s facial growth and development. Also the device can be a valuable tool for evaluating the results of orthodontic and orthopedic treatments.

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