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| Principle and Method of Automatic Calibration in Digital Image Processing of Rail Wear |
| WU Fu-hua, YU Xue-cai, WU Ke-qing, ZHANG Lei |
| School of Optoelectronic Information, UESTC, Chengdu, Sichuan 610054, China |
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Abstract A simple implicit parameter calibration method is proposed. The transition matrix element which is also called implicit parameter is obtained from the relation between the calibration board feature points world coordinates and its corresponding distorted image coordinates. Then the measured image is restored to the world coordinate system for measuring which can be seen as the image obtained from the case that the camera perpendiculars to the measured plane and under the case of no distortion in the lens. This method is used in the rail wear image measurement. After field test, it shows that the image calibration accuracy reaches 0.2mm and accuracy of the measurement system is better than 0.5mm which meets the requirements of the standard.
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2013, Vol. 34 
