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考虑圆心偏差补偿的分步相机标定方法

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在视觉测量领域,高精度的相机标定往往采用圆形目标。为了解决主流相机标定算法使用圆心标定造成圆心偏差、使用全参数优化产生过拟合或容易陷入局部最优解、以及忽略畸变中心产生标定误差的问题,本文提出了一种考虑圆心偏差补偿的分步相机标定方法,用于实现单目相机的高精度标定。首先,与传统的单图像畸变校正方法不同,本文提出的多图像畸变校正方法可以计算共同的畸变中心和系数,使畸变校正精度更高,稳定性和计算效率更强;其次,将圆心投影点与圆轮廓投影中心的差值作为圆心偏差进行补偿,重复迭代上述过程,使标定结果精度更高更稳定;最后,通过最小化重投影误差对相机参数非线性优化,完成畸变参数和相机参数的分步式标定,进一步提高了标定结果的鲁棒性。另外,本文通过模块对比实验研究了圆心偏差补偿和相机参数优化对相机标定的影响,结果表明两者都可提升标定精度,且后者作用更大,当两者同时使用时标定精度和稳定性进一步得到提高。本文进行了计算机仿真和真实实验,均证明了本文所提方法具有较高的精度、较强的稳定性和鲁棒性,可用于高精度的视觉测量领域。
A stepwise camera calibration method incorporating compensation for eccentricity error
In visual measurement,high-precision camera calibration often employs circular targets.To address issues in mainstream methods,such as the eccentricity error of the circle from using the circle's center for calibration,overfitting or local minimum from full-parameter optimization,and calibration errors due to neglecting the center of distortion,a stepwise camera calibration method incorporating compensation for eccentricity error was proposed to enhance monocular camera calibration precision.Initially,the multi-image distortion correction method calculated the common center of distortion and coefficients,improving precision,stability,and efficiency compared to single-image distortion correction methods.Subsequently,the projection point of the circle's center was compared with the center of the contour's projection to iteratively correct the eccentricity error,leading to more precise and stable calibration.Finally,nonlinear optimization refined the calibration parameters to minimize reprojection error and boosts precision.These processes achieved stepwise camera calibration,which enhanced robustness.In addition,the module comparison experiment showed that both the eccentricity error compensation and the camera parameter optimization could improve the calibration precision,but the latter had a greater impact.The combined use of the two methods further improved the precision and stability.Simulations and experiments confirmed that the proposed method achieved high precision,stability,and robustness,suitable for high-precision visual measurements.

camera calibrationerror compensationeccentricity errordistortion correctioncenter of distortionoptical measurement

魏家起、王鹏、李岳、李默晶、李林、孙长库、付鲁华

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天津大学精密测试技术及仪器全国重点实验室,天津 300072

相机标定 圆心偏差 误差补偿 畸变校正 畸变中心 光学测量

2024

测试科学与仪器
中北大学

测试科学与仪器

影响因子:0.111
ISSN:1674-8042
年,卷(期):2024.15(4)