Camera calibration method based on improved distortion model

A camera calibration and distortion model technology, applied in the field of computer vision, can solve problems such as low precision, complex implementation, and non-convergent results

Inactive Publication Date: 2017-12-22
NANJING UNIV OF SCI & TECH
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Problems solved by technology

[0003] Currently the most widely used camera calibration method is Zhang Zhengyou calibration method, but it only considers the influence of radial distortion
Due to the randomness of lens manufacturing, the distribution of various distortion errors in the image is not completely consistent, so it is difficult to find a distortion model that can accurately reflect the degree of image distortion in practical applications
In addition, in the existing Zhang Zhengyou calibration method, the dimension to be solved is often large, which leads to non-convergence of the results or long calculation time during the optimization process, and the problems of complex implementation and low accuracy

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  • Camera calibration method based on improved distortion model

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Embodiment 1

[0129] This embodiment is a camera calibration method based on an improved distortion model.

[0130] combine image 3 , Table 1, since the accuracy of the calibration board directly affects the accuracy of the calibration results, the checkerboard calibration board used in the embodiment of the present invention is as follows image 3 The specific parameters of the calibration board are shown in Table 1.

[0131] Combined with Table 2, it can be found in the calibration process that the difference in the number of calibration images has a certain impact on the calibration results. In order to obtain relatively stable internal parameters of the camera, 15 to 25 calibration images of different poses are used in the embodiment of the present invention to calibrate the camera used, and the calibration results are shown in Table 2.

[0132] Table 1. Checkerboard Calibration Board Parameters Used

[0133]

[0134] Table 2 The results of calibrating the cameras used with 15-25...

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Abstract

The invention discloses a camera calibration method based on an improved distortion model. The method comprises the following steps: according to the transformation relationship between a world coordinate system and an image coordinate system, establishing a camera calibration model; according to orthogonal property of a matrix, obtaining a constraint equation of internal parameters of a camera; approximately calculating an initial value through a linear solution method, and then, calculating a homography matrix through a gradient method; according to the calculated constraint equation and the homography matrix, calculating camera model parameters; combining Zhengyou Zhang and Heikkila calibration models, changing solving order of the two ends of a distortion model equation according to radial distortion and tangential distortion, and calculating the initial value through a linear least square method; and carrying out optimization solution on the camera parameters through a Levenberg-Marquardt algorithm to obtain optimal camera parameters. The method realizes camera calibration and has the advantages of high calibration precision and easy implementation.

Description

technical field [0001] The invention belongs to the technical field of computer vision, in particular to a camera calibration method based on an improved distortion model. Background technique [0002] Camera calibration refers to shooting a special calibration plate under the camera model, then processing the captured calibration image, and obtaining the internal and external parameters of the camera model through coordinate transformation, so as to obtain the relative position of the camera in the world coordinate system. Location. Since the camera calibration is required in the process of detecting the remaining thickness of the pantograph slide plate wear and the length of the crack, the length of the detection target in the image is converted into the actual physical length to obtain high-precision measurement results. Therefore, it is particularly important to calibrate the camera accurately. [0003] Currently the most widely used camera calibration method is Zhang ...

Claims

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Application Information

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IPC IPC(8): G06T7/80
CPCG06T7/80G06T2207/30208
Inventor 刘新海陈叶健俞赛艳白良留裴卫卫邢宗义
Owner NANJING UNIV OF SCI & TECH
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