scholarly journals Compressive Sensing Based Three-Dimensional Imaging Method with Electro-Optic Modulation for Nonscanning Laser Radar

Symmetry ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 748
Author(s):  
Yulong An ◽  
Yanmei Zhang ◽  
Haichao Guo ◽  
Jing Wang
Keyword(s):  
Compressive Sensing ◽  
3D Imaging ◽  
Low Cost ◽  
Functional Model ◽  
Three Dimensional ◽  
Visible Spectrum ◽  
Depth Map ◽  
Imaging Method ◽  
Practical Applications ◽  
Electro Optic

Low-cost Laser Detection and Ranging (LiDAR) is crucial to three-dimensional (3D) imaging in applications such as remote sensing, target detection, and machine vision. In conventional nonscanning time-of-flight (TOF) LiDAR, the intensity map is obtained by a detector array and the depth map is measured in the time domain which requires costly sensors and short laser pulses. To overcome such limitations, this paper presents a nonscanning 3D laser imaging method that combines compressive sensing (CS) techniques and electro-optic modulation. In this novel scheme, electro-optic modulation is applied to map the range information into the intensity of echo pulses symmetrically and the measurements of pattern projection with symmetrical structure are received by the low bandwidth detector. The 3D imaging can be extracted from two gain modulated images that are recovered by solving underdetermined inverse problems. An integrated regularization model is proposed for the recovery problems and the minimization functional model is solved by a proposed algorithm applying the alternating direction method of multiplier (ADMM) technique. The simulation results on various subrates for 3D imaging indicate that our proposed method is feasible and achieves performance improvement over conventional methods in systems with hardware limitations. This novel method will be highly valuable for practical applications with advantages of low cost and flexible structure at wavelengths beyond visible spectrum.

scholarly journals Automatic Detection Technology of Sonar Image Target Based on the Three-Dimensional Imaging

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Wanzeng Kong ◽  
Jinshuai Yu ◽  
Ying Cheng ◽  
Weihua Cong ◽  
Huanhuan Xue
Keyword(s):  
Data Storage ◽  
3D Imaging ◽  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
Automatic Detection ◽  
Classification Model ◽  
Image Detection ◽  
Practical Applications ◽  
Sonar Image ◽  
Detection Technology

With 3D imaging of the multisonar beam and serious interference of image noise, detecting objects based only on manual operation is inefficient and also not conducive to data storage and maintenance. In this paper, a set of sonar image automatic detection technologies based on 3D imaging is developed to satisfy the actual requirements in sonar image detection. Firstly, preprocessing was conducted to alleviate the noise and then the approximate position of object was obtained by calculating the signal-to-noise ratio of each target. Secondly, the separation of water bodies and strata is realized by maximum variance between clusters (OTSU) since there exist obvious differences between these two areas. Thus image segmentation can be easily implemented on both. Finally, the feature extraction is carried out, and the multidimensional Bayesian classification model is established to do classification. Experimental results show that the sonar-image-detection technology can effectively detect the target and meet the requirements of practical applications.

scholarly journals Cone-Beam Three-Dimensional Dental Volumetric Tomography in Dental Practice

2017 ◽  
Vol 7 (3) ◽  
pp. 62 ◽  
Author(s):  
Suzan Cangul ◽  
Ozkan Adiguzel
Keyword(s):  
Soft Tissues ◽  
Low Cost ◽  
Three Dimensional ◽  
Cone Beam ◽  
Imaging Method ◽  
Dental Practice ◽  
3 Dimensional ◽  
Scanning Time ◽  
Technological Advances ◽  
Native Speakers Of English

Imaging methods are of great importance for diagnosis and treatment in dentistry. With technological advances, great progress has been made in these methods. Over time, 3-dimensional (3-D) imaging has replaced 2-dimensional, thereby providing examination of objects in all directions. Of these methods, which play an important role in the clinical evaluation of patients, cone-beam computed tomography (CBCT) is the newest and most advanced imaging method. This method will revolutionize dental in comparison with conventional CT, it has several advantages, including a shorter scanning time, low radiation dose, low cost and the acquisition of high-resolution images. With 3-D imaging technology, this method has introduced the possibility of applying several procedures from diagnosis in the maxillofacial region to operative and surgical procedures. Although very clear results are not obtained from the imaging of soft tissues, the most important advantage of this technology is the capability of imaging hard and soft tissues together.   How to cite this article: Cangul S, Adiguzel O. Cone-Beam Three-Dimensional Dental Volumetric Tomography in Dental Practice. Int Dent Res 2017;7:62-70.  Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

scholarly journals Microdroplet-guided intercalation and deterministic delamination towards intelligent rolling origami

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Borui Xu ◽  
Xinyuan Zhang ◽  
Ziao Tian ◽  
Di Han ◽  
Xingce Fan ◽  
...  
Keyword(s):  
Low Cost ◽  
Rolling Direction ◽  
Three Dimensional ◽  
Van Der Waals Interaction ◽  
Creative Design ◽  
General Strategy ◽  
Practical Applications ◽  
On Demand ◽  
Vapor Sensing ◽  
Fundamental Research

Abstract Three-dimensional microstructures fabricated by origami, including folding, rolling and buckling, gain great interests in mechanics, optics and electronics. We propose a general strategy on on-demand and spontaneous rolling origami for artificial microstructures aiming at massive and intelligent production. Deposited nanomembranes are rolled-up in great amount triggered by the intercalation of tiny droplet, taking advantage of a creative design of van der Waals interaction with substrate. The rolling of nanomembranes delaminated by liquid permits a wide choice in materials as well as precise manipulation in rolling direction by controlling the motion of microdroplet, resulting in intelligent construction of rolling microstructures with designable geometries. Moreover, this liquid-triggered delamination phenomenon and constructed microstructures are demonstrated in the applications among vapor sensing, microresonators, micromotors, and microactuators. This investigation offers a simple, massive, low-cost, versatile and designable construction of rolling microstructures for fundamental research and practical applications.

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 Cylindrical Three-Dimensional Millimeter-Wave Imaging via Compressive Sensing

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Guoqiang Zhao ◽  
Shiyong Li ◽  
Bailing Ren ◽  
Qingwei Qiu ◽  
Houjun Sun
Keyword(s):  
Compressive Sensing ◽  
Millimeter Wave ◽  
Imaging Techniques ◽  
New Technology ◽  
Three Dimensional ◽  
Sampling Theorem ◽  
Future Application ◽  
Imaging Method ◽  
Wave Imaging ◽  
The Cost

Millimeter-wave (MMW) imaging techniques have been used for the detection of concealed weapons and contraband carried by personnel. However, the future application of the new technology may be limited by its large number of antennas. In order to reduce the complexity of the hardware, a novel MMW imaging method based on compressive sensing (CS) is proposed in this paper. The MMW images can be reconstructed from the significantly undersampled backscattered data via the CS approach. Thus the number of antennas and the cost of system can be further reduced than those based on the traditional imaging methods that obey the Nyquist sampling theorem. The effectiveness of the proposed method is validated by numerical simulations as well as by real measured data of objects.

scholarly journals A Novel 3D Imaging Method for Airborne Downward-Looking Sparse Array SAR Based on Special Squint Model

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Xiaozhen Ren ◽  
Yao Qin ◽  
Lihong Qiao
Keyword(s):  
3D Imaging ◽  
Three Dimensional ◽  
Imaging Method ◽  
Computationally Efficient ◽  
Theory Analysis ◽  
Imaging Geometry ◽  
Range Resolution ◽  
Sparse Array ◽  
Resolution Imaging ◽  
Cross Track

Three-dimensional (3D) imaging technology based on antenna array is one of the most important 3D synthetic aperture radar (SAR) high resolution imaging modes. In this paper, a novel 3D imaging method is proposed for airborne down-looking sparse array SAR based on the imaging geometry and the characteristic of echo signal. The key point of the proposed algorithm is the introduction of a special squint model in cross track processing to obtain accurate focusing. In this special squint model, point targets with different cross track positions have different squint angles at the same range resolution cell, which is different from the conventional squint SAR. However, after theory analysis and formulation deduction, the imaging procedure can be processed with the uniform reference function, and the phase compensation factors and algorithm realization procedure are demonstrated in detail. As the method requires only Fourier transform and multiplications and thus avoids interpolations, it is computationally efficient. Simulations with point scatterers are used to validate the method.

scholarly journals Introduction to 3D Imaging Using Photogrammetry

2018 ◽  
Vol 2 ◽  
pp. e27029
Author(s):  
JP Brown
Keyword(s):  
3D Imaging ◽  
Low Cost ◽  
Three Dimensions ◽  
Imaging Method ◽  
Laptop Computer ◽  
Full Color ◽  
Single Lens ◽  
Hands On ◽  
Museum Professionals ◽  
Full Day

This full day workshop will provide an introduction to 3D imaging using photogrammetry. The course is designed for museum professionals who are already familiar with using digital single lens reflex (DSLR) cameras, and want to extend their practice to 3D imaging. Photogrammetry is a low-cost-of-entry 3D imaging method which can be used to produce excellent results for many different museum specimens, and scales well. From large buildings to tiny clay molds, photogrammetry has been used to successfully model and document a very wide variety of museum material in full color and in three dimensions. The technique can also be extended to multi-spectral imaging. The workshop will be hands-on and will cover camera setup, lighting, and image processing, imaging flat and contoured specimens. We will look at working at different scales, and metric photogrammetry using Agisoft Photoscan. The course will be led by a museum professional with five years of experience of using photogrammetry to image museum collections from bivalves and taxidermy to textiles, and fossils to furniture. Due to the intensive and fast-moving nature of the workshop, participation is limited to eight people. Participants will be expected to bring a DSLR and a laptop computer to the workshop.

scholarly journals True-Color Three-Dimensional Imaging and Target Classification Based on Hyperspectral LiDAR

2019 ◽  
Vol 11 (13) ◽  
pp. 1541 ◽  
Author(s):  
Chen ◽  
Shi ◽  
Gong ◽  
Sun ◽  
Chen ◽  
...  
Keyword(s):  
3D Imaging ◽  
Spectral Band ◽  
Three Dimensional ◽  
Principal Component ◽  
Support Vector ◽  
Imaging Method ◽  
Spectral Correlation ◽  
Spectral Bands ◽  
True Color ◽  
Band Combinations

True-color three-dimensional (3D) imaging exploits spatial and spectral information and can enable accurate feature extraction and object classification. The existing methods, however, are limited by data collection mechanisms when realizing true-color 3D imaging. We overcome this problem and present a novel true-color 3D imaging method based on a 32-channel hyperspectral LiDAR (HSL) covering a 431–751 nm spectral range. We conducted two experiments, one with nine-color card papers and the other with seven different colored objects. We used the former to investigate the effect of true-color 3D imaging and determine the optimal spectral bands for compositing true-color, and the latter to explore the classification potential based on the true-color feature using polynomial support vector machine (SVM) and Gaussian naive Bayes (NB) classifiers. Since using all bands of HSL will cause color distortions, the optimal spectral band combination for better compositing the true-color were selected by principal component analysis (PCA) and spectral correlation measure (SCM); PCA emphasizes the amount of information in band combinations, while SCM focuses on correlation between bands. The results show that the true-color 3D imaging can be realized based on HSL measurements, and three spectral bands of 466, 546, and 626 nm were determined. Comparing reflectance of the three selected bands, the overall classification accuracy of seven different colored objects was improved by 14.6% and 8.25% based on SVM and NB, respectively, classifiers after converting spectral intensities into true-color information. Overall, this study demonstrated the potential of HSL system in retrieving true-color and facilitating target recognition, and can serve as a guide in developing future three-channel or multi-channel true-color LiDAR.

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