Robust detection and ordering of ellipses on a calibration pattern

Álvarez, Luis; Salgado, Agustín; Sánchez, Javier

doi:10.1134/s1054661807040098

Cited by 5 publications

(3 citation statements)

References 16 publications

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“…Due to the advantage of easy detection and high accuracy positioning, the circular target is widely adopted in stereovision field . In civil engineering, the circular target is usually mounted on structural surface for measuring structural deformations .…”

Section: Three‐step Calibration Algorithmmentioning

confidence: 99%

Stereovision monitoring for entire collapse of a three-story frame model under earthquake excitation

Shan

Yuan

Wang

et al. 2018

Struct Control Health Monit

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Summary During the stage of structural collapse, conventional contact sensors are usually taken away from structure to protect sensors, and the entire displacement curves of structural collapse cannot be acquired. To deal with this problem, a stereovision‐based displacement measurement method is used to monitor the entire structural collapse. To improve measurement accuracy, a three‐step calibration algorithm based on solid circle target is proposed to calibrate stereovision system in this paper. The Digital Image Correlation method is employed to perform sequential image matching of circular target on structural surface. A set threshold of correlation criterion is introduced to eliminate image mismatch, and the reference image is correspondingly updated to conduct later matching under large deformations of structures. A shaking table test of a 3‐story frame model under El Centro earthquake is performed in lab. Experimental results indicate that the displacement curves acquired by the proposed stereovision method and linear variable differential transformers agree well, and this testifies the reliability and effectiveness of the presented stereovision method. Compared with our previous stereovision method, the proposed stereovision method has a higher precision and faster running speed. This demonstrates that the proposed stereovision method is more suitable for the actual use and can monitor the entire process of structural collapse.

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Section: Three‐step Calibration Algorithmmentioning

confidence: 99%

Stereovision monitoring for entire collapse of a three-story frame model under earthquake excitation

Shan

Yuan

Wang

et al. 2018

Struct Control Health Monit

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show abstract

“…Up to now, 2D plane calibration template is adopted in most camera calibration, which includes checkerboard, grid template and circle array template [4]. Circle feature [8][9][10] is prone to be detected, and has advantages of high orientation accuracy of its center and high computation speed, so it is used extensively to industrial machine vision applications. Fig.…”

Section: Parameter Solutionmentioning

confidence: 99%

A Novel Camera Calibration Method Based on Circle Array Target

Wang

Ding

2012

AMR

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To improve accuracy of computer visual inspection in keyboard automatic assembly line, a new two-stage camera calibration method was presented. 2D circle array was used as calibration plate, and centers of the circles were taken as feature points. And feature point coordinates were extracted without human interference. The proposed camera calibration method was divided into two stages. First, lens distortion was neglected, internal and external parameters of the camera were obtained by modified camera calibration toolbox for MATLAB. Then, lens distortion was taken into account, and improved genetic algorithm (GA) was adopted to optimize camera parameters gotten in the first stage. Experiment results indicate the proposed method is feasible, and can meet with requirements of the given application.

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“…System calibration precision directly influences the measurement precision. There are many calibration methods [3][4][5][6]. According to the characteristic parameters of the circular saw blade, the standard gauge block was used as a calibration reference.…”

Section: Image Processing and Camera Calibrationmentioning

confidence: 99%

Visual Integrated Measurement on Geometry Parameters of Circular Saw Blade

Liu

Zhao²,

Dai³

2010

AMR

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Established the circular saw blade visual measurement system and developed geometry parameters measurement software. Calculated the inner and outer circle diameters and the roundness error, the tooth angle and the radial rake angle, the radial direction clearance angle on the basis of image processing. Calibrated the measured part using the standard gauge block. Improved the circle and the line sub-pixel methods. Experiment results showed that the fitting error of improved least–square linear fitting method was quarter of ordinary least–square linear fitting error under small difference of orientation time. The diameters of the inner circle and the outer circle ,the roundness error ,the tooth cusp angle and the radial rake angle, the radial direction clearance angle were respectively 25.204mm, 193.624mm, 0.005mm, 59.999°±0.00695°, 15.004°±0.0104°, 14.997°±0.0137° while taken sub-pixel method.

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Robust detection and ordering of ellipses on a calibration pattern

Cited by 5 publications

References 16 publications

Stereovision monitoring for entire collapse of a three-story frame model under earthquake excitation

Stereovision monitoring for entire collapse of a three-story frame model under earthquake excitation

A Novel Camera Calibration Method Based on Circle Array Target

Visual Integrated Measurement on Geometry Parameters of Circular Saw Blade

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