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基于SIFT特征匹配的小变形初值估计研究

Study on initial guess of small deformation based on SIFT feature matching

  • 摘要: 为了克服基于尺度不变特征变换(SIFT)特征匹配的小变形初值估计受到特征点误匹配和匹配精度不确定性的影响,引入了对误匹配引起的异常值具有一定抗性的最小一乘算法和霍夫变换算法进行拟合获取变形初值。通过模拟散斑图实验检验最小一乘算法和霍夫变换算法的小变形初值估计可靠性,与随机抽样一致性算法的结果进行了对比;并通过相似模拟实验检验初值算法真实情况下的可靠性。结果表明,在小位移情形下,最小一乘算法的位移初值标准差低于霍夫变换算法和随机抽样一致性算法,为0.0033 pixel ~0.0068 pixel,且在数字图像相关方法中使用其位移初值的相关搜索平均迭代次数为3.692~4.370次;对于实验过程中散斑图出现的破损区域,最小一乘算法的位移初值和数字图像相关方法的位移测量值存在明显差值,最大值为11.80 pixel,最小值为−7.35 pixel,最小一乘算法的变形初值依然可靠,但数字图像相关方法的变形测量有失效风险。该研究为数字图像相关方法的小变形初值估计提供了一定的参考。

     

    Abstract: In order to overcome the impact of mismatched feature points and uncertainty in matching accuracy on initial guess of small deformation based on scale-invariant feature transform (SIFT) feature matching, least absolute deviation algorithm and Hough transform algorithm which are reasonably resistant to outliers caused by mismatches were introduced to obtain initial deformation values. The reliability of initial guess of small deformation calculated from the least absolute deviation algorithm and Hough transform algorithm were verified with the simulated speckle pattern experiments, and the results of two algorithms were compared with that of random sample consensus algorithm. In addition, the reliability of the initial guess algorithm in a real scene was verified with a similar simulation experiment. The results show that the standard deviations of the initial displacements of the absolute deviation algorithm are ranging from 0.0033 pixel to 0.0068 pixel, lower than that of the Hough transform algorithm and the random sampling consistency algorithm in the case of small displacement. The average number of iterations for the correlation search using its initial displacement is 3.692 to 4.370 in the digital image correlation method. For the damaged region in the speckle pattern during the experiment, there is a significant difference between the initial displacement of the least squares algorithm and the displacement measurement of the digital image correlation method, with a maximum of 11.80 pixel and a minimum of −7.35 pixel. The least absolute deviation algorithm still provides reliable initial values, but the digital image correlation method has a risk of deformation measurement failure. This study provides some reference for initial guess of small deformation in the digital image correlation method.

     

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