Article
Engineering, Electrical & Electronic
Pengfei Sun, Fuqiang Zhou, Lin Wang, Wanning Zhang, Yang Liu, Lemiao Yang
Summary: Multiviewpoint or multisensor 3-D vision measurement is widely used for large-scale measurement. However, the parameters of the global camera used for unifying the local measurement coordinates are easily affected by external factors, reducing the accuracy of the 3-D reconstruction. Therefore, a novel camera calibration method based on a flexible multidirectional target (FMT) is proposed to solve this problem.
IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT
(2023)
Article
Optics
Junzhou Huo, Haidong Zhang, Zhichao Meng, Fan Yang, Guiyu Yang
Summary: This paper proposes a flexible calibration method for defocused cameras in complex engineering scenes. The method achieves high calibration accuracy by solving the distortion coefficient and establishing an image distance conversion model through linear camera calibration based on image pairs. Experimental results show that the method is effective and has satisfactory calibration accuracy and good anti-noise performance.
OPTICS AND LASERS IN ENGINEERING
(2022)
Article
Engineering, Electrical & Electronic
Yujian Pan, De Bast, Sofie Pollin
Summary: This article focuses on indoor direct positioning using a practical MIMO array, introducing a method for on-site array calibration and a two-stage positioning scheme. Experimental results demonstrate that the proposed method achieves high accuracy and superior performance.
IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT
(2021)
Article
Optics
Xing Qu, Pengyu Hu, Huiwen Deng, Yu Duan, Shuming Yang
Summary: This paper proposes two methods based on blinking pattern and calibration panel motion to solve the problem of DVS not being able to directly detect traditional control points. The experimental results show that both methods can significantly reduce the standard deviation compared to the conventional methods.
OPTICS AND LASERS IN ENGINEERING
(2023)
Article
Computer Science, Information Systems
Congcong Li, Jing Li, Yuguang Xie, Jiayang Nie, Tao Yang, Zhaoyang Lu
Summary: In this paper, a novel calibration-free cross-camera target association algorithm is proposed to relate local visual data of the same object across cameras with overlapping FOVs. The algorithm utilizes the interactions between objects and their spatiotemporal consistency to associate cameras. It has wide applicability in multi-camera systems with unknown or rarely available calibration data and large perspective gaps between cameras. Experimental evaluations verify the effectiveness and robustness of the proposed method.
IEEE TRANSACTIONS ON MULTIMEDIA
(2023)
Article
Optics
Yulong Yin, Huabing Zhu, Pei Yang, Zhaohui Yang, Kai Liu, Hongwei Fu
Summary: This paper proposes a high-precision and robust binocular camera calibration method based on a coding target. The method improves the stability and robustness of calibration results by designing a coding target with simple patterns and using a rapid, robust, and accurate decoding algorithm. Additionally, the introduction of zenith and azimuth angles enhances the robustness of the calibration. Furthermore, a multi-constraint optimization method is proposed to refine the parameters of the binocular camera and improve the accuracy of calibration. Experimental results confirm the effectiveness of the proposed method.
Article
Chemistry, Analytical
Lazaros Grammatikopoulos, Anastasios Papanagnou, Antonios Venianakis, Ilias Kalisperakis, Christos Stentoumis
Summary: In this paper, a simple and intuitive approach for estimating the calibration of a Lidar instrument with respect to a camera and their synchronization shifting during data acquisition is presented. The calibration is achieved by estimating the 3D rigid transformation of the camera system with respect to the Lidar frame based on 2D to 3D point correspondences. The AprilTag fiducial marker and custom-made retroreflective target are used for extracting 2D points and detecting Lidar points, respectively. After the geometrical calibration, the temporal calibration is carried out by matching the position of AprilTag to the corresponding Lidar target. The proposed method provides highly accurate results in both single-camera-to-Lidar calibration and multi-camera texturing scheme of city point clouds.
Article
Chemistry, Multidisciplinary
Zean Bu, Changku Sun, Peng Wang, Hang Dong
Summary: This work presents a novel method for calibrating light detection and ranging (LiDAR) with a camera, utilizing a specially designed calibration target to obtain intrinsic and extrinsic parameters. Experimental results demonstrate the effectiveness of this calibration method in obtaining accurate results.
APPLIED SCIENCES-BASEL
(2021)
Article
Engineering, Multidisciplinary
Jianbin Cao, Xu Zhang, Dawei Tu, Guangya Zhou
Summary: Calibration of out-of-focus cameras is crucial for some special 3D reconstruction applications. This paper proposes a vision-guided calibration method, including an optimal pose selection algorithm and an iterative phase-target technology. The method improves the calibration accuracy by simultaneously optimizing the mathematical properties of the solution and the angular uncertainty of the corners.
Article
Engineering, Electrical & Electronic
Sanghyun Yoon, Sungha Ju, Hieu Minh Nguyen, Sangyoon Park, Joon Heo
Summary: This study proposes a novel spatiotemporal calibration method that accurately estimates seven parameters, improving the accuracy of sensor data fusion.
IEEE SENSORS JOURNAL
(2022)
Article
Engineering, Electrical & Electronic
Sebastian Schramm, Johannes Rangel, Daniela Aguirre Salazar, Robert Schmoll, Andreas Kroll
Summary: This article compares different types of camera calibration targets in the visible, near infrared, medium-wave infrared, and long-wave infrared spectral ranges, finding that a single target can provide good results across all ranges, which is particularly important for the extrinsic calibration of cameras of different wavelengths. The contrast-to-noise ratio and different OpenCV feature detection algorithms are shown to be reasons for varying calibration quality with different targets.
IEEE SENSORS JOURNAL
(2021)
Article
Chemistry, Analytical
Xudong Lv, Shuo Wang, Dong Ye
Summary: In this paper, a novel CNN-based LiDAR-camera extrinsic calibration algorithm named CFNet is proposed, which introduces a correlation layer and innovatively defines a calibration flow to improve calibration accuracy by considering geometric information, outperforming current CNN methods on the KITTI dataset.
Article
Computer Science, Information Systems
Jonguk Kim, Hyansu Bae, Suk Gyu Lee
Summary: This paper proposes a stereo camera calibration method based on calibration and validation techniques, with experimental results demonstrating its efficiency.
Article
Multidisciplinary Sciences
Wei-wei Sheng
Summary: This paper proposes a precise measurement method and corresponding calibration procedure for a line structure light vision sensor with a large measurement range. By utilizing a linear translation stage and planar target, the relationship between the center point of the laser stripe and the perpendicular/horizontal distance is obtained. The proposed method eliminates the need for distortion compensation and significantly improves measurement precision.
SCIENTIFIC REPORTS
(2023)
Article
Engineering, Electrical & Electronic
Wei Zou, Zhenzhong Wei
Summary: The paper proposes a flexible calibration method for multicameras, simulating a hand-eye calibration problem and using only a few calibration images to solve it. By optimizing camera parameters simultaneously and introducing epipolar constraint, the calibration accuracy is improved, addressing the stability issues in multicamera calibration.
IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT
(2021)
Article
Optics
Tianyue He, Qican Zhang, Mingwei Zhou, Tingdong Kou, Junfei Shen
Summary: This paper presents an end-to-end snapshot hyperspectral imaging technique using a physics-informed dual attention neural network for multimodal learning. By modeling the 3D spectral cube reconstruction procedure and solving compressive-imaging inverse problem, the hyperspectral volume can be directly recovered from an RGB image. The proposed method is faster and more precise than traditional scanning methods, and offers great potential for future spectral imaging applications.
Article
Optics
Xiaolong Ke, Tianyi Wang, Zili Zhang, Lei Huang, Chunjin Wang, Vipender S. Negi, Weslin C. Pullen, Heejoo Choi, Daewook Kim, Mourad Idir
Summary: With the rapid development of precision technologies, the demand for high-precision optical surfaces has increased significantly. This paper studies the strategies for multi-tool dwell time optimization and proposes an innovative method for simultaneously scheduling dwell time for multiple tools. The effectiveness of the proposed method is validated through simulation and experiment.
Article
Optics
Zhoujie Wu, Wenbo Guo, Qican Zhang, Haoran Wang, Xunren Li, Zhengdong Chen
Summary: In this work, a time-overlapping structured-light 3D shape measuring technique is proposed to achieve high-speed and high-performance measurement on complex dynamic scenes. The technique reduces information redundancy, ensures measuring robustness, and improves measuring accuracy. Experimental results demonstrate the effectiveness of the proposed method in various complex dynamic scenes.
Article
Optics
Tingdong Kou, Qican Zhang, Chongyang Zhang, Tianyue He, Junfei Shen
Summary: This paper presents a computational imaging system that integrates dual-aperture optics and a physics-informed dual-encoder neural network to achieve large depth-of-field (DOF) extension. The system combines a small-aperture NIR camera and a large-aperture VIS camera to provide sharp edges and faithful color. A specific network with parallel double encoders and a multi-scale fusion module is proposed to solve the imaging inverse problem and preserve delicate scene textures. Experimental results demonstrate that the method effectively produces high-fidelity images with a larger DOF range. The system has the potential for various vision applications such as smartphone photography, computational measurement, and medical imaging.
Article
Chemistry, Multidisciplinary
Yueyang Li, Wenbo Guo, Junfei Shen, Zhoujie Wu, Qican Zhang
Summary: In this paper, a method based on three-stream neural networks is proposed to reduce motion-induced error, and a general dataset establishment method for dynamic scenes is introduced. Experimental results demonstrate that the proposed method significantly improves the traditional phase-shifting algorithm and is promising for high-speed 3D measurement.
APPLIED SCIENCES-BASEL
(2022)
Article
Optics
Sijie Zhu, Yiping Cao, Qican Zhang, Yajun Wang
Summary: By proposing a high-efficiency and robust binary fringe optimization method, this paper achieves superfast 3D shape measurement with high accuracy. The method combines 1D optimization and 2D modulation to overcome the challenges of achieving high accuracy and high speed simultaneously.
Article
Optics
Yansong Jiang, Zhoujie Wu, Yuankun Liu, Xin Yu, Qican Zhang
Summary: The conventional CTHPU algorithm is effective for measuring isolated objects or discontinuous surfaces, but not suitable for high-speed applications. We propose a MTHPU algorithm that can update a 3D result in dynamic scenes using only four fringe patterns, achieving high accuracy and efficiency.
OPTICS AND LASERS IN ENGINEERING
(2023)
Article
Optics
Wei Xu, Weihe Xu, Nathalie Bouet, Juan Zhou, Hanfei Yan, Xiaojing Huang, Lei Huang, Ming Lu, Maxim Zalalutdinov, Yong S. Chu, Evgeny Nazaretski
Summary: We have developed a new machine-learning-based approach for automatically measuring small angles between multiple planar surfaces characterized by white light interferometers. This method utilizes an unsupervised clustering algorithm to identify the distinct surfaces in interferometer images and calculates the angles between them through surface fitting. The method simplifies the angle measurement procedure and has been successfully applied to the alignment of 2D Multilayer Laue Lenses (MLLs) for high-resolution x-ray microscopy, demonstrating its automatic, accurate, and robust small-angle measurement capabilities.
OPTICS AND LASERS IN ENGINEERING
(2023)
Article
Optics
Tianyue He, Qican Zhang, Chongyang Zhang, Tingdong Kou, Junfei Shen
Summary: A digital lens (DL) is proposed to compensate for chromatic aberration and a neural network is used to address wavelength-independent degradation. This method reduces optical complexity and achieves achromatic imaging in the analog domain.
Article
Optics
Lei Huang, Lukas Lienhard, Tianyi Wang, Francois Polack, Josep Nicolas, Steven Hulbert, Mourad Idir
Summary: We have developed the Multi-Pitch Nano-accuracy Surface Profiler (MPNSP) to characterize strongly curved X-ray mirrors for diffraction-limited soft X-ray focusing. The measurement process involves forward-and-backward scans along the tangential direction at multiple pitch angles. Our research and development aim to measure strongly curved X-ray mirrors with a large slope range while maintaining high measurement repeatability and self-consistency.
OPTICS AND LASERS IN ENGINEERING
(2023)
Article
Optics
Weslin C. Pullen, Tianyi Wang, Heejoo Choi, Xiaolong Ke, Vipender S. Negi, Lei Huang, Mourad Idir, Daewook Kim
Summary: Computer-controlled optical surfacing (CCOS) systems have become more deterministic in achieving target surface profiles, but the optimal set of tool sizes for the shortest run time is difficult to determine. This paper proposes the characteristic frequency ratio (CFR) as a measure for tool correction capability and quantitatively studies different CFRs' performance in tool size selection using computer simulation. The study finds that CFR = 0.75 achieves the most stable trade-off between run time and iterations, providing a general criterion for tool size selection in CCOS processes.
Article
Optics
Xin Lai, Yueyang Li, Xunren Li, Zhengdong Chen, Qican Zhang
Summary: This paper proposes a quadratic phase estimation method using the extended Kalman filter to remove the phase error introduced by uncertain phase shift, improving the accuracy of the phase-measuring profilometry (PMP) system. By eliminating background and fringe modulation, the proposed method evaluates the quadratic phase coefficients and estimates phase shifts to compute the unwrapping phase. Experimental results show that the algorithm effectively evaluates the actual phase shift, compensates the phase error, and demonstrates high speed, high accuracy, and robustness.
Article
Optics
Yueyang Li, Zhouejie Wu, Junfei Shen, Qican Zhang
Summary: This paper proposes a method for real-time processing and 3D measurement of dynamic scenes based on network architecture search. By designing a lightweight neural network and employing an improved dual-frequency strategy, high-accuracy 3D reconstruction and measurement are achieved.
Article
Engineering, Electrical & Electronic
Zhoujie Wu, Zhengdong Chen, Zhaosheng Chen, Haoran Wang, Wenbo Guo, Xunren Li, Qican Zhang
Summary: In this study, a chromatic digital image correlation-assisted fringe projection profilometry method is proposed for accurate 3-D shape, deformation measurement, and strain analysis. Colorful fluorescent pigment is introduced to fabricate speckle patterns, and an optimal fluorescent color is determined to ensure high fringes intensity modulation and speckles' chroma difference. The method overcomes the contradictions between fringe projection profilometry and digital image correlation on the requirement of surface reflectivity, and can provide accurate measurement of shape, deformation, and strain.
IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT
(2023)
Article
Optics
Zhengdong Chen, Xunren Li, Haoran Wang, Zhaosheng Chen, Qican Zhang, Zhoujie Wu
Summary: This paper proposes a method for multi-dimensional information sensing based on digital image correction-assisted fringe projection profilometry. By introducing fluorescent markers and a general information separation method, accurate and high-resolution multi-dimensional information can be obtained and analyzed.
