在大型结构件的损伤监测过程中,摄像机镜头畸变往往引起成像畸变,如果直接利用畸变图像进行标定、测量,将引起较大误差,降低损伤监测精度。为了有效地校正成像畸变,提出一种改进的基于直线特征的非量测畸变校正方法。分析实际测量中成像畸变的像差模型;直接利用场景中存在的直线特征,得到带权重因子的直线射影不变约束关系和三点近似共线约束关系,并建立两组畸变校正约束方程求解畸变系数;通过实验验证提出方法的可行性和有效性。校正结果表明,相比不带权重的直线特征标定方法,提出方法优化结果的均方根误差精度提高了0.21 pixel。

The camera lens distortion often causes image distortion during damage monitoring process of large structures, great errors will be resulted and damage detection accuracy will be reduced if the distorted image is directly used for calibration and measurement. We propose an improved non-metric distortion calibration method based on straight line characteristics to correct the distortion effectively. Firstly, we analyze the aberration model of the distorted image in actual measurement. Then, we obtain the constraint relationships with weighting factors based on the principle of linear projective invariance and three-point approximate collinearity according to the straight line features in the scene, and establish two sets of distortion correction constraint equations to solve the distortion parameters. Finally, the feasibility and validity of the proposed method is demonstrated experimentally. Root mean square error of the proposed method is improved by 0.21 pixel compared with the calibration method based on the linear feature without weighting factors.