- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Charuco Board-Based Omnidirectional Camera Calibration Method
摘要： In this paper, we propose a Charuco board-based omnidirectional camera calibration method to solve the problem of conventional methods requiring overly complicated calibration procedures. Specifically, the proposed method can easily and precisely provide two-dimensional and three-dimensional coordinates of patterned feature points by arranging the omnidirectional camera in the Charuco board-based cube structure. Then, using the coordinate information of the feature points, an intrinsic calibration of each camera constituting the omnidirectional camera can be performed by estimating the perspective projection matrix. Furthermore, without an additional calibration structure, an extrinsic calibration of each camera can be performed, even though only part of the calibration structure is included in the captured image. Compared to conventional methods, the proposed method exhibits increased reliability, because it does not require additional adjustments to the mirror angle or the positions of several pattern boards. Moreover, the proposed method calibrates independently, regardless of the number of cameras comprising the omnidirectional camera or the camera rig structure. In the experimental results, for the intrinsic parameters, the proposed method yielded an average reprojection error of 0.37 pixels, which was better than that of conventional methods. For the extrinsic parameters, the proposed method had a mean absolute error of 0.90° for rotation displacement and a mean absolute error of 1.32 mm for translation displacement.
关键词： virtual reality,camera calibration,omnidirectional camera
更新于2025-09-23 15:23:52
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Virtual Image Points Based Geometrical Parameters’ Calibration for Focused Light Field Camera
摘要： In the light field imaging, the geometrical parameters' calibration of the light field camera is the foundation of computational imaging techniques, such as the calibration of the light field data, digital refocusing, depth reconstruction, all-in-focus imaging, and so on. In this paper, we propose a virtual image points based geometrical parameters' calibration for focused light field camera. In the forward model, the mapping from the object points to the virtual image points with respect to the main lens as well as the mapping from the virtual image points to the image points on the detector with respect to the microlens array are established. While calibrating geometrical parameters, the inverse problem of calculating the virtual image points from the corner on the detector is established and the model of calculating the geometrical parameters of the focused light field camera is established. Levenberg–Marquardt algorithm is used to solve the geometrical parameters iteratively. We use the checkerboard for the calibration experiment and validate the calculation via the reprojection of the checkerboard corners.
关键词： computational imaging,virtual image point,light field camera,Camera calibration
更新于2025-09-23 15:23:52
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[IEEE 2018 Colour and Visual Computing Symposium (CVCS) - Gj?vik (2018.9.19-2018.9.20)] 2018 Colour and Visual Computing Symposium (CVCS) - Evaluation of Color Correction Methods for Printed Surfaces
摘要： Achieving truthful reproduction of color is a well-known problem for printing applications. In this paper, we evaluate different methods for camera color calibration, within the scope of a moving image acquisition system. The acquisition device consists of a RGB camera and two fixed tungsten lamps. Our goal is to determine the most robust end-to-end framework given the acquisition conditions. We tested some color mapping methods commonly mentioned in the literature and made modifications to our specific needs. Our modified 3D lookup table (LUT) based method performs the best in the given conditions with future possibilities of hybrid LUTs combining the best performing aspects of different types of LUTs.
关键词： color correction,camera calibration,color calibration,color imaging
更新于2025-09-23 15:23:52
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A STUDY OF NEAR-INFRARED (NIR) FILTER FOR SURVEILLANCE APPLICATION
摘要： Lately, most illegal activities occur in the dead of night when most of the surveillance cameras cannot capture movements clearly. Therefore, Near-Infrared (NIR) filter was used to increase the visualization of suspect identification when the image or footage is captured in a dark environment. The objective of this study was to determine the optimum NIR filters based on the stability of the camera calibration parameters and to evaluate the accuracy of mapping. In this study, four NIR filters with different wavelengths (715, 780, 830, and 850 nm) were tested. The investigation comprised: (1) the calibrations of the camera and NIR filters and (2) a case study involving a simulation test for surveillance application. The type of sensor used was a digital video camera (Sony HC5E HDV) and the camera was set up at multiple stations to form a single convergence configuration. The statistical Analysis of Variance (ANOVA) was used in this study to find (differences in) the significance of the NIR imaging in the calibration and three-dimensional (3D) measurement. The results showed that the camera parameters varied for every type of filter used and this influenced the 3D measurement of the object mapping. In summary, the 850 nm NIR filter was the most optimum for surveillance application based on the stability of the camera calibration and the standard deviation in the mapping accuracy.
关键词： three-dimensional (3D) measurement,camera calibration,Near-infrared filters
更新于2025-09-23 15:22:29
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Temperature Compensation Method for Digital Cameras in 2D and 3D Measurement Applications
摘要： This paper presents the results of several studies concerning the effect of temperature on digital cameras. Experiments were performed using three different camera models. The presented results conclusively demonstrate that the typical camera design does not adequately take into account the effect of temperature variation on the device’s performance. In this regard, a modified camera design is proposed that exhibits a highly predictable behavior under varying ambient temperature and facilitates thermal compensation. A novel temperature compensation method is also proposed. This compensation model can be applied in almost every existing camera application, as it is compatible with every camera calibration model. A two-dimensional (2D) and three-dimensional (3D) application of the proposed compensation model is also described. The results of the application of the proposed compensation approach are presented herein.
关键词： temperature effect,3D imaging,structured light,camera calibration
更新于2025-09-23 15:21:21
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Hybrid Plasmonic Waveguide based 3??3 Multimode Interferometer for Compact 120?° Optical Hybrid
摘要： The Kinect system is arguably the most popular 3-D camera technology currently on the market. Its application domain is vast and has been deployed in scenarios where accurate geometric measurements are needed. Regarding the PrimeSense technology, a limited amount of work has been devoted to calibrating the Kinect, especially the depth data. The Kinect is, however, inevitably prone to distortions, as independently confirmed by numerous users. An effective method for improving the quality of the Kinect system is by modeling the sensor’s systematic errors using bundle adjustment. In this paper, a method for modeling the intrinsic and extrinsic parameters of the infrared and colour cameras, and more importantly the distortions in the depth image, is presented. Through an integrated marker- and feature-based self-calibration, two Kinects were calibrated. A novel approach for modeling the depth systematic errors as a function of lens distortion and relative orientation parameters is shown to be effective. The results show improvements in geometric accuracy up to 53% compared with uncalibrated point clouds captured using the popular software RGBDemo. Systematic depth discontinuities were also reduced and in the check-plane analysis the noise of the Kinect point cloud was reduced by 17%.
关键词： 3D/stereo scene analysis,quality assurance,quantization,camera calibration,Kinect
更新于2025-09-23 15:21:01
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3D tracking of multiple onsite workers based on stereo vision
摘要： Varied sensing technologies have been delved in for positioning workers and equipment in construction sites. Vision-based technology has been received growing attentions by the virtue of its tag-free and inexpensive con?guration. One of the core research works in this area was the use of stereo camera system for tracking 3D locations of construction resources. However, the previous work was limited to tracking of a single entity. To overcome the limitation, this paper presents a new framework for tracking multiple workers. The proposed framework supplements the previous work by embedding an additional step, entity matching, which ?nds corresponding matches of tracked workers across two camera views. Entity matching takes advantage of the epipolar geometry and workers' motion directions for ?nding correct pairs of a worker's projections on two image planes. This paper also presents an e?ective approach of camera calibration for positioning entities located a few tens of meters away from the cameras. The proposed framework is evaluated based on completeness, continuity, and localization accuracy of the generated trajectories. The evaluation results have shown its capability of retrieving 96% of actual movements, within localization errors of 0.821 m with 99.7% con?dence.
关键词： Occlusion,Computer vision,Entity matching,Tracking,Construction worker,Site monitoring,Camera calibration
更新于2025-09-23 15:21:01
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A Study on the Uncertainty of a Laser Triangulator Considering System Covariances
摘要： A laser triangulation system, which is composed of a camera and a laser, calculates distances between objects intersected by the laser plane. Even though there are commercial triangulation systems, developing a new system allows the design to be adapted to the needs, in addition to allowing dimensions or processing times to be optimized; however the disadvantage is that the real accuracy is not known. The aim of the research is to identify and discuss the relevance of the most significant error sources in laser triangulator systems, predicting their error contribution to the final joint measurement accuracy. Two main phases are considered in this study, namely the calibration and measurement processes. The main error sources are identified and characterized throughout both phases, and a synthetic error propagation methodology is proposed to study the measurement accuracy. As a novelty in uncertainty analysis, the present approach encompasses the covariances of correlated system variables, characterizing both phases for a laser triangulator. An experimental methodology is adopted to evaluate the measurement accuracy in a laser triangulator, comparing it with the values obtained with the synthetic error propagation methodology. The relevance of each error source is discussed, as well as the accuracy of the error propagation. A linearity value of 40 μm and maximum error of 0.6 mm are observed for a 100 mm measuring range, with the camera calibration phase being the main error contributor.
关键词： accuracy,camera calibration,laser triangulation,laser calibration,uncertainty,covariances
更新于2025-09-23 15:19:57
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Real-Time Weld Quality Prediction Using a Laser Vision Sensor in a Lap Fillet Joint during Gas Metal Arc Welding
摘要： Nondestructive test (NDT) technology is required in the gas metal arc (GMA) welding process to secure weld robustness and to monitor the welding quality in real-time. In this study, a laser vision sensor (LVS) is designed and fabricated, and an image processing algorithm is developed and implemented to extract precise laser lines on tested welds. A camera calibration method based on a gyro sensor is used to cope with the complex motion of the welding robot. Data are obtained based on GMA welding experiments at various welding conditions for the estimation of quality prediction models. Deep neural network (DNN) models are developed based on external bead shapes and welding conditions to predict the internal bead shapes and the tensile strengths of welded joints.
关键词： deep neural network,camera calibration,laser vision sensor,gas metal arc welding,weld quality prediction
更新于2025-09-23 15:19:57
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[IEEE 2020 IEEE 20th Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems (SiRF) - San Antonio, TX, USA (2020.1.26-2020.1.29)] 2020 IEEE 20th Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems (SiRF) - 28 Gbps Bang-Bang CDR for 100G PSM4 with Independently Tunable Proportional and Integral Parameters of the Loop Filter in $0.25\ \mu \mathrm{m}$ Photonic BiCMOS Technology
摘要： The Kinect system is arguably the most popular 3-D camera technology currently on the market. Its application domain is vast and has been deployed in scenarios where accurate geometric measurements are needed. Regarding the PrimeSense technology, a limited amount of work has been devoted to calibrating the Kinect, especially the depth data. The Kinect is, however, inevitably prone to distortions, as independently confirmed by numerous users. An effective method for improving the quality of the Kinect system is by modeling the sensor’s systematic errors using bundle adjustment. In this paper, a method for modeling the intrinsic and extrinsic parameters of the infrared and colour cameras, and more importantly the distortions in the depth image, is presented. Through an integrated marker- and feature-based self-calibration, two Kinects were calibrated. A novel approach for modeling the depth systematic errors as a function of lens distortion and relative orientation parameters is shown to be effective. The results show improvements in geometric accuracy up to 53% compared with uncalibrated point clouds captured using the popular software RGBDemo. Systematic depth discontinuities were also reduced and in the check-plane analysis the noise of the Kinect point cloud was reduced by 17%.
关键词： 3D/stereo scene analysis,quality assurance,quantization,camera calibration,Kinect
更新于2025-09-23 15:19:57