Earticle

By leveraging the characteristics of both quantum encoding and classical data channel, we present a unique and novel multiuser optical communication system that utilizes fascinating properties of the structured light for information transmission. Specifically, we propose an indoor orbital angular momentum (OAM) multiuser multiple-input multiple-output (MIMO) optical communication system, where the quantum encoding is performed and the multiuser transmission is then analyzed from the context of the classical data channel. In the proposed system, as the OAM beam propagates, its angular spread is analyzed. In addition, we show that the variance of the beam divergence increases with the increasing OAM index mode on the basis of the derived MIMO channel impulse response for OAM carrying Laguerre?Gaussian beams. Comparative studies reveal that the proposed system significantly outperforms the conventional non-orthogonal multiple access (NOMA) applied with MIMO.

3차원 공간에서 물체를 재구성하기 위하여 제안된 기존 기법들은 여러 개의 카메라를 사용하거나 여러장의 사진을 촬영하여 물체를 재구성하기 때문에 특정한 하드웨어를 필요로 하거나 촬영 장소에 민감하고 시간이 오래 걸린다는 단점이 있다. 본 논문에서는 유비쿼터스 환경에서 구조광 기법을 이용하여 한 장의 사진의 정보로부터 3차원 물체를 재구성하는 방법을 제안한다. 구조광 기법 적용을 위한 칼라 패턴은 기존연구에서 제안된 것을 사용한다. 본 논문에서는 실제로 객체 재구성 성능에 매우 중요한 줄무늬 패턴 추출과 줄무늬 패턴 매칭에 다양한 영상 처리 기법들로 구성된 파이프라인을 새롭게 제안하고, 패턴 매칭을 위한 최적의 비용 함수를 제안한다. 제안 기법을 통하여 갤럭시 빔과 같은 초소형 프로젝터를 탑재한 스마트폰과 같은 유비쿼터스 혹은 모바일 환경에서 적은 계산 복잡도와 간단한 환경 설정으로 3차원 물체를 재구성하는 것이 가능하다.

Since conventional methods for the reconstruction of 3D objects used a number of cameras or pictures, they required specific hardwares or they were sensitive to the photography environment with a lot of processing time. In this paper, we propose a 3D object reconstruction method using one photograph based on structured light in ubiquitous environments. We use color pattern of the conventional method for structured light. In this paper, we propose a novel pipeline consisting of various image processing techniques for line pattern extraction and matching, which are very important for the performance of the object reconstruction. And we propose the optimal cost function for the pattern matching. Using our method, it is possible to reconstruct a 3D object with efficient computation and easy setting in ubiquitous or mobile environments, for example, a smartphone with a subminiature projector like Galaxy Beam.

The measurement in the manufacturing process of curved ship hull plates still depends on wooden templates as a standard instrument. The metrology-enabled automation in the shipbuilding process has been challenged instead of line measurement with wooden templates. The developed measurement system consists of a CCD camera, multiple structured laser sources and 3-DOF motion device. The system carries out measurement of curved profiles for large scale plates by an optical triangulation method. The results of experiment conducted in a manufacturing shop demonstrate the accurate and robust performance.

Inner structured and bonded panel, or ISB Panel, as a kind of sandwich type panel, has metallic inner structures which have low relative density, because of their dimensional shape of metal between a pare of metal skin sheets or face sheets. In this work, ISB panels and inner structures formed as repeated pyramidal shapes are introduced. Pyramidal structures are formed easily with expanded metal sheet by the crimping process. Three kinds of pyramidal structures are made and used to fabricate test specimen. Through the multi-point electrical resistance welding, inner structures are bonded with skin sheet. 3-point bending tests are carried out to measure the bending stiffness of ISB panel and experimental results are discussed.

Inner structured and bonded panel, or ISB Panel, as a kind of sandwich type panel, has metallic inner structures which have low relative density, due to their dimensional shape of metal between a pair of metal skin sheets or face sheets. Previous works showed that ISB panels containing inner structures formed as repeated pyramidal shapes saved weight up to $60\%$ in condition of same stiffness comparing with solid sheet. In this work, woven metal is adapted to inner structures replacing pyramidal structures. The test specimens of ISB panel containing woven metal made by multi-point electric resistance welding and 3-point bending test have been carried out. The results of experiments and comparisons of process parameters, stiffness and failure mode are discussed.

A 3D reconstruction based on the multi-frequency structured light is proposed to reduce phase error using an adaptive compensation method. The phase error of the traditional 3D reconstruction with the structured light originates from various sources such as lens distortion, the nonlinear imaging system and a nonsinusoidal fringe pattern that can be very difficult to model. An adaptive compensation algorithm is introduced to reduce adaptively the phase error resulting from the fringe pattern

Purpose: This study aimed to compare the accuracy of intra-oral and model scanners using structured light scanning technology in the external, internal, and marginal surfaces of a single zirconia crown. Methods: The maxillary right first molar was selected as the abutment tooth, and an impression was taken to create a master model. Each specimen was scanned 10 times using an intra-oral scanner (IOS group; i600, MegaGen Implant) and a model scanner (MS group) (n=20). All scan data were exported and saved in standard tessellation language format. A three-dimensional analysis program was employed to evaluate the root mean square (RMS) deviations across the external, internal, and marginal surfaces. Statistical analysis was performed using IBM SPSS Statistics 26.0 (IBM), with the Shapiro–Wilk test applied for normality and the Mann–Whitney U test (α=0.05). Results: In the trueness analysis, no statistically significant differences were found between the 2 groups for the external and marginal surfaces (p>0.05). However, the MS group demonstrated significantly higher trueness in the internal surface (p=0.008). In the precision analysis, the IOS group showed higher precision on the external surface, whereas the MS group had higher precision on both the internal and marginal surfaces, with significant differences observed across all surfaces (p<0.05). Conclusion: This study revealed that the MS group demonstrated higher trueness and precision in certain areas. Both scanners achieved accuracy within 120 μm, confirming their potential for clinical application.

본 논문에서는 태양광 발전에 사용되는 대형 집광반사판의 형상측정을 통하여 3D 곡률도, 왜곡도 및 집광률 등을 측정하는 방법을 제안한다. 집광반사판의 경우 다양한 형태의 왜곡으로 인해 집광효율이 감소 할 수 있고, 효율적인 집광을 위하여 곡률과 왜곡 등의 측정 데이터 피드백을 통한 반사판의 곡률 최적화 작업이 필요하다. 곡률도 및 집 광률 측정은 레이저 라인 스캔 방식을 통해 정밀측정이 가능하나 시간이 매우 오래 걸리는 단점이 있고 이를 해결하 기 위해 다양한 구조광 패턴 반사기법들이 지속적으로 연구되고 있다. 본 논문에서는 대형 집광반사판의 곡률도 및 집광률 측정을 위하여 구조광 패턴 편향법(structural light pattern deflectometry : SLPD)을 제안한다. 제안 하는 방법은 빔프로젝터-스크린-측정반사판-카메라로 측정환경을 구성하고, 평면거울을 이용하여 기하보정 및 구조 광 패턴 주소 등록을 수행한다. 그리고 반사판에 의해 변형되어 측정된 구조광 패턴을 기하보정 결과에 적용하여 표 면형상에 대한 X, Y축 gradient를 구하고, integration 계산을 통해 3차원 형상을 복원한다. 복원된 3차원 형상 은 이상적인 설계모델과 비교를 통해 곡률도, 왜곡도 및 집광률 등의 측정이 가능하다.

In this paper, we propose a method to measure 3D curvature, distortion, and light condensation rate by measuring the shape of a large condensing reflector used in solar power generation. In the case of the condensed reflector, the condensing efficiency can be reduced due to various types of distortion. Therefore the curvature optimization operation of the reflector through feedback of measurement data such as curvature and distortion is required for efficient condensing. The curvature and the light collection rate can be measured precisely by the laser line scanning method. However, there are disadvantages that the time is very long, and various structured light pattern reflection techniques are continuously studied to solve this problem. In this paper, we propose structural light pattern deflectometry (SLPD) for the measurement of the curvature and the light collection rate of a large condensed reflector. The proposed method constructs the measurement environment with a beam projector - screen - measurement reflector - camera and performs geometry calibration and registration of structured optical pattern address using a plane mirror. Then, the structural light pattern deformed by the reflector is applied to the geometrical calibration result to obtain the X and Y axis gradients of the surface shape, and the 3D shape is restored by integration calculation. The reconstructed 3D shape can be measured by comparing with the ideal design model, such as curvature, distortion and light-condensing rate.

In structured light 3D measurement field, when the object has smooth surface, it can form a highlight area due to the specular reflection, and the distortion of the object will make a large measurement error. In order to solve this problem, this paper use seven steps sine-phase shift combined with linear diffuser to remove highlight. Firstly, the principle of removing specular with diffuser is analyzed, then the overall design of the system is introduced, which includes 3D reconstruction and system calibration method. Finally the reconstructed experiments are carried out with ceramic plate. Experimental results show that the proposed method can significantly reduce the highlights area of reconstructed image compared with the highlights area without diffuser. The diffuser can obviously inhibited by highlights, although it can not completely remove the highlights, it plays a very important role in reconstructing specular object with more accurate and better quality.

The key problem of computer vision reconstruction technology is to improve accuracy of shape reconstruction and authenticity of color reconstruction. First, color edge Gray code is presented, which encodes with red and blue Gray code stripes, and decodes with sub-pixel located stripe edges. So quantization error and decoding error were eliminated and accuracy of shape reconstruction was improved. Second, color correction method is presented. The coupling phenomena of RGB primary colours existed in the encode and decode process was analyzed, and then Color coupler Correction scheme based on Caspi model Hardware Calibration was designed. Accordingly, a color imbalance caused by the surface curvature in the reconstruction process was analyzed, and color imbalance correction scheme used surface geometric information was also proposed. Shape reconstruction experimental results show that relative error of reconstructed plane is 0.05%, and reconstructed complex surface has same visual effects as real surface. Color reconstruction experimental results show that color of reconstructed surface is uniform after correction, which has same color as real surface. And moreover, This method has strong anti-interference ability and can help to improve the accuracy of shape and color reconstruction.

The existing structured light measurement technologies mainly focus on the single color objects, especially for measuring white object. Mainly because of in the process of three-dimensional measurement for color objects, color object’s surface has a great influence on color components of structured light, leading to the color of structured light changing, this will cause serious errors in the decoding process. To solve this problem, combined with the actual measurements for colored objects, this paper adopts a color Gray code for encoding and decoding structured light, and presents an obtaining technical for color components of structured light, which first through regression analysis builds a mathematical model, and then uses the least squares method for solving it, at last restores the color of the projected stripes to ensure the correctness of decoding, to achieve the measurement for color object and to improve the measurement accuracy. The experimental results show that this method has a good effect on decoding.

As an efficient and reliable method in 3D reconstruction and active measurement, structured light vision technology is being more and more important. Structured light vision technology by one or more image coding pattern projection to measure the scenario, and with the position of the projection direction at an angle with the camera intake scene projection image, and then match the projected image and the code pattern corresponding points using trigonometric obtain a 3D scene information. In order to achieve accurate projection image and coding pattern matching, on the one hand need effective structured light coding method, on the other hand, it is necessary to use a variety of image processing method to accurately locate the position of the projection image feature points. In this paper, a color structured light coding and decoding method based on topology structured and regional structured model is proposed. Finally, the methods for extracting encoded feature points based on waveform analysis and for classifying colors based on clustering analysis are developed. The result of the experiment has shown that the proposed method has good performance for the structured light vision system.

3D scanners are needed in various fields, and their usage range is greatly expanded. In particular, it is being used to reduce costs at various stages during product development and production. Now, the importance of quality inspection in the manufacturing industry is increasing. Structured optical system applied in this study is suitable for measuring high precision of mold, press work, precision products, etc. and economical and effective 3D scanning system for measuring inspection in manufacturing industry can be implemented. We developed Structured light 3D scanner which can measure high precision by using Digital Light Processing (DLP) projector and camera. In this paper, 3D image scanner based on structured optical system can realize 3D scanning system economically and effectively when measuring inspection in the manufacturing industry.

Currently, it is usually a 3D scanner processing method as a laser method. However, the laser method has a disadvantage of slow scanning speed and poor precision. Although optical scanners are used as a method to compensate for these shortcomings, optical scanners are closely related to the distance and precision of the object, and have the disadvantage of being expensive. In this paper, 3D scanner using variable focus lens-based structured light module with improved measurement precision was designed to be high performance, low price, and usable in industrial fields. To this end, designed a telecentric optical system based on a variable focus lens and connected to the telecentric mechanism of the step motor and lens to adjust the focus of the variable lens. Designed a connection structure with optimized scalability of hardware circuits that configures a stepper motor to form a system with a built-in processor. In addition, by applying an algorithm that can simultaneously acquire high-resolution texture image and depth information and apply image synthesis technology and GPU-based high-speed structured light processing technology, it is also stable for changes to external light. We will designed and implemented for further improving high measurement precision.

In order to establish the 3D Temperature Field based on structure light 3D measurement and cross-correlation registration. Infrared/Visible camera calibration method and heterologous images registration method were studied. First, according to infrared camera’s characteristics, the selection of calibration templates have been studied and the calibration of the infrared camera has been accomplished on the basis of planar calibration method; then, we simplified the two-step method based on the mature principle of structure light measurement; and the visible camera was calibrated; finally, use calibrated visible cameras to form structured light measurement system, and register the infrared image and visible image in the geometrical position. Experimental results show that: the relative error of measurement system is less than 0.3%;infrared and visible image’s alignment error in geometrical position is 0.0015 mm. and measurement systems have good reconstruction results for plane and curved ,and cross-correlation method has a good effect for heterrologous images registration.

This paper describes a low-cost miniaturized 3D reconstruction approach using structured light. By projecting known patterns onto a surface, shape and structure of the surface can be measured and characteristic parameters of deformation can be determined. Existing approaches use large geometries and complex optical components. Here we present our system with the size of a cigarette pack and a working distance of only 6 cm. The theoretical depth resolution of the system is determined by the resolution of the camera and the projector as well as the system geometry and was found to be about 100 μm.

제본된 책이나 고문서를 디자타이즈할 때 책을 바르게 펴지 못하거나 지정된 위치나 방위로 위치시키지 못해서 문제가 발생한다. 특히 힘을 가할 수 없는 고문서의 경우에는 바르게 펼수가 없기 때문에 깊이 차이에 의한 문서의 왜곡이 발생한다. 본 연구에서는 Structured Light을 이용하여 깊이 차에 의한 문자의 왜곡을 복원하는 방안을 제안한다. 또한 입력시 책의 위치와 방위에 대한 제한을 완화시킬 수 있도록 책의 위치와 방위 변화에 적을 알 수 있는 방안을 제안한다,

This paper describes the implementation of document image restoration system for the geometric distortion using structured light. To get accurate document images, the bounded book must be flattened by pushing down the book with a class plate. However, most of ancient documents are too fragile to be pushed. The proposed system restores the distorted character image due to geometric distortion.

본 논문은 이동 로보트가 실제 환경속에서 주행할 수 있도록 하기 위한 간단한 structured light 센서의 개발과 이용에 관한 연구로써, 이동로보트에 이 센서를 부착하였을 경우 그 적용범위는 첫째, 복잡한 3차원 물체들 속에서의 실시간 주행경로 주변 물체의 모델링과 인식을 위한 것으로 나뉠 수 있다. 개발된 센서가 갖추고 있는 데이타 습득 속도와 정확도는 실용화 하기에 충분하며, 여러 다양한 상황속에서의 실험을 통하여 이를 확인하였다.

In this paper, a robust and simple structured light sensory system has been studied to endow mobile robots with the ability of navigating in real world. A mobile robot with this sensor can be applied in two ways: first, real time navigation in 3-dimensional world, second, modeling and recognition of environment. Range data obtained with this sensor are fairy accurate, and the data aquisition speed is satisfactory. Experiments in diverse situation show effectiveness of the structured light sensor for the mobile robot.

In this paper, a novel 3D reconstruction method is proposed for radiation environments based on structured light technology. Firstly, throughout the principles of structured light-based 3D reconstruction, we see that the primary sources of error in radiation environments are the impacts of radiation noise and point-cloud registration errors. Then, considering the random nature of radiation noise, this paper proposes a multiframe iterative image-filtering algorithm that effectively and quickly removes radiation noise while preserving the phase information of the structured light. Additionally, a point-cloud initial registration method based on image features is introduced, which reduces the time required for initial matching and ensures accuracy. 3D reconstruction experiments were conducted at radiation dose rates of 60 Gy/h and 100 Gy/h. The results demonstrate that the proposed method maintains high modeling accuracy even in high-radiation environments, validating the reliability of the approach.