Common self-polar triangle of separate circles for light field camera calibration

Due to the trade-off between spatial resolution and angular resolution of the light field, it is difficult to extract high precision corner points and line features from light fields for calibration. A novel calibration pattern of separate circles is designed, and a light field camera calibration method based on common self-polar triangle with respect to separate circles is proposed in this paper. First, we explore the uniquity and reconstruction of common self-polar triangle with respect to sperate circles. Then, based on projections of the multi-projection-center model on the plane and conic, the common self-polar triangle on the sub-aperture image is reconstructed and used to estimate planar homography. Finally, a light field camera calibration algorithm is then proposed, including linear initialization and non-linear optimization. Experimental results on both synthetic and real data have verified the effectiveness and robustness of the method and algorithm proposed.

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Camera Calibration Method Based on Circle Plane Board

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.475-476.184 ◽

2013 ◽

Vol 475-476 ◽

pp. 184-187

Author(s):

Wen Guo Li ◽

Shao Jun Duan

Keyword(s):

Camera Calibration ◽

Calibration Method ◽

Lens Distortion ◽

Edge Extraction ◽

Circle Plane ◽

Circle Centre ◽

Extraction Algorithm ◽

Calibration Algorithm ◽

Characteristic Points ◽

Distortion Parameters

We present a camera calibration method based on circle plane board. The centres of circles on plane are regarded as the characteristic points, which are used to implement camera calibration. The proposed calibration is more accurate than many previous calibration algorithm because of the merit of the coordinate of circle centre being obtained from thousand of of edge pionts of ellipse, which is very reliable to image noise caused by edge extraction algorithm. Experiments shows the proposed algorithm can obtain high precise inner parameters, and lens distortion parameters.

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Industrial part localization and grasping using a robotic arm guided by 2D monocular vision

Industrial Robot the international journal of robotics research and application ◽

10.1108/ir-06-2018-0128 ◽

2018 ◽

Vol 45 (6) ◽

pp. 794-804 ◽

Cited By ~ 3

Author(s):

Zhaohui Zheng ◽

Yong Ma ◽

Hong Zheng ◽

Yu Gu ◽

Mingyu Lin

Keyword(s):

Camera Calibration ◽

High Precision ◽

Calibration Method ◽

Monocular Vision ◽

Robotic Arm ◽

Robot Arm ◽

Content Type ◽

Calibration Algorithm ◽

Target Locating ◽

Practical Implications

Purpose The welding areas of the workpiece must be consistent with high precision to ensure the welding success during the welding of automobile parts. The purpose of this paper is to design an automatic high-precision locating and grasping system for robotic arm guided by 2D monocular vision to meet the requirements of automatic operation and high-precision welding. Design/methodology/approach A nonlinear multi-parallel surface calibration method based on adaptive k-segment master curve algorithm is proposed, which improves the efficiency of the traditional single camera calibration algorithm and accuracy of calibration. At the same time, the multi-dimension feature of target based on k-mean clustering constraint is proposed to improve the robustness and precision of registration. Findings A method of automatic locating and grasping based on 2D monocular vision is provided for robot arm, which includes camera calibration method and target locating method. Practical implications The system has been integrated into the welding robot of an automobile company in China. Originality/value A method of automatic locating and grasping based on 2D monocular vision is proposed, which makes the robot arm have automatic grasping function, and improves the efficiency and precision of automatic grasp of robot arm.

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Camera Calibration Method Based on Halcon

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.385-386.518 ◽

2013 ◽

Vol 385-386 ◽

pp. 518-522

Author(s):

Zhi Xian Zhang ◽

Li Liang ◽

Yong Deng

Keyword(s):

Computer Vision ◽

Camera Calibration ◽

Ccd Camera ◽

Calibration Method ◽

Geometrical Model ◽

Accuracy Analysis ◽

Calibration Algorithm ◽

Cross Platform ◽

Computation Speed

Aiming at the applications of computer vision,a nonlinear image geometrical model for array CCD camera was build and the interior parameters and exterior parameters as well were analyzed.By applying Halcon calibration board with circular targets plane of matrix gridding type and functions library,a camera calibration algorithm and accuracy analysis were given.Experiments indicated that the parameters were accurate and this method is simple and it improves the calibration precision and computation speed, and has a good cross-platform portability.

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Holographic Micromirror Array with Diffuse Areas for Accurate Calibration of 3D Light-Field Display

Applied Sciences ◽

10.3390/app10207188 ◽

2020 ◽

Vol 10 (20) ◽

pp. 7188

Author(s):

Lode Jorissen ◽

Ryutaro Oi ◽

Koki Wakunami ◽

Yasuyuki Ichihashi ◽

Gauthier Lafruit ◽

...

Keyword(s):

Light Field ◽

3D Visualization ◽

Calibration Method ◽

Automatic Calibration ◽

Display System ◽

Extrinsic Parameters ◽

Calibration Algorithm ◽

Fully Automatic ◽

Intrinsic And Extrinsic Parameters ◽

Micromirror Array

Light field 3D displays require a precise alignment between the display source and the micromirror-array screen for error free 3D visualization. Hence, calibrating the system using an external camera becomes necessary, before displaying any 3D contents. The inter-dependency of the intrinsic and extrinsic parameters of display-source, calibration-camera, and micromirror-array screen, makes the calibration process very complex and error-prone. Thus, several assumptions are made with regard to the display setup, in order to simplify the calibration. A fully automatic calibration method based on several such assumptions was reported by us earlier. Here, in this paper, we report a method that uses no such assumptions, but yields a better calibration. The proposed method adapts an optical solution where the micromirror-array screen is fabricated as a computer generated hologram with a tiny diffuser engraved at one corner of each elemental micromirror in the array. The calibration algorithm uses these diffusing areas as markers to determine the relation between the pixels of display source and the mirrors in the micromirror-array screen. Calibration results show that virtually reconstructed 3D scenes align well with the real world contents, and are free from any distortion. This method also eliminates the position dependency of display source, calibration-camera, and mirror-array screen during calibration, which enables easy setup of the display system.

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The Projector Calibration Based on ZHANG’s Self-Calibration Method

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.981.364 ◽

2014 ◽

Vol 981 ◽

pp. 364-367

Author(s):

Guang Yu ◽

Bo Yang Yu ◽

Shu Cai Yang ◽

Li Wen ◽

Wen Fei Dong ◽

...

Keyword(s):

Camera Calibration ◽

Dimensional Space ◽

Three Dimensional ◽

Calibration Method ◽

Linear Calibration ◽

Self Calibration ◽

Operation Process ◽

Projector Calibration ◽

Calibration Algorithm ◽

Relationship Of

Projector calibration can be seen as a special case of the camera calibration. It can establish the relationship of the three dimensional space coordinates for points and projector image coordinates for points DMD by using a projector to project coding pattern. In camera calibration, ZHANG’s self-calibration was conducted in the maximum likelihood linear refinement. Operation process takes the lens distortion factors into account finding out the camera internal and external parameters finally. Using this algorithm to the projector calibration can solve the traditional linear calibration algorithm which is complex and poor robustness. Otherwise, it can improve the practicability of calibration method. This method can both calibrate the internal and external parameters of projector, which can solve the problem of independently inside or outside calibration.

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Camera Calibration Method Based on Vanishing Point

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.513-517.3719 ◽

2014 ◽

Vol 513-517 ◽

pp. 3719-3722

Author(s):

Wen Guo Li ◽

Shao Jun Duan

Keyword(s):

Camera Calibration ◽

Calibration Method ◽

Experimental Results ◽

Vanishing Point ◽

Feature Points ◽

Vanishing Points ◽

Parallel Lines ◽

Internal Parameters ◽

The Matrix ◽

Calibration Algorithm

We present a camera calibration method based on vanishing point, that is, the vanishing points of two groups of parallel lines on the target plane are used to achieve camera calibration. A series of known positions points on target plane are used as the feature points, and the target images are recorded, the image coordinates of feature points are used to calculate the coordinates of vanishing point, then the matrix between feature points and camera is used to obtain internal parameters of camera. Experimental results show that the proposed calibration algorithm is correct, simple and convenient.

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Research on the Substation 3D Real Scene Surveillance

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1008-1009.742 ◽

2014 ◽

Vol 1008-1009 ◽

pp. 742-747 ◽

Cited By ~ 1

Author(s):

Hao Chen ◽

Ya Ping Hu ◽

Jin Gyi Yan ◽

Jiong Cong Chen ◽

Juan Hu

Keyword(s):

Video Surveillance ◽

Camera Calibration ◽

Surveillance System ◽

Calibration Method ◽

Video Monitoring ◽

Video Surveillance System ◽

Monitoring Point ◽

Technical Problems ◽

Real Scene ◽

Calibration Algorithm

The reasonable distribution of the video monitoring points in the substation is one of the technical problems to be solved in the engineering. We combined the camera calibration algorithm with the real application of the substation video monitoring point layout, and proposed a nonlinear camera calibration method of the external parameters based on the 3D real scene, which is suited for the substation video surveillance system. The optimal video monitoring points are determined by the relationship between the video produced by the camera movement and the visual scope displayed with the 3D real scene, and testified by the location of each object through its boundary geometric element shown in the pictures. It has been proved applicable by the video simulating analysis on the 110kV main transformer monitoring points. This method has been used in the engineering design of the Guangdong Power Grid substation video surveillance system.

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