针对圆形标志点标定鱼眼镜头模型参量准确度不高的问题, 提出一种基于质心点优化的鱼眼相机标定方法.首先在已有的鱼眼镜头成像模型的基础上, 获取模型内外参量的初值, 并利用两步求解法求取畸变参量的初值；然后通过模型求取标志圆的投影椭圆, 对该投影椭圆和图像上的椭圆分别求质心, 进而建立目标函数并优化模型各参量, 最后实现鱼眼镜头的精确标定.模拟实验和真实图像实验结果均表明: 本文提出的方法能够明显提高鱼眼镜头的标定准确度, 为鱼眼视觉相关问题的研究提供了可靠的参量依据.

Due to the low calibration accuracy for fisheye lenses by using circular control points, this paper proposes a fisheye camera calibration algorithm optimized by centroid method. Firstly, initial values of intrinsic and extrinsic parameters of imaging model were obtained, and then initial value of distortion parameters were solved by Two Step method. Secondly, centroid of ellipse detected from image and ellipse projected by imaging model were solved respectively. Then distance between those two centroid was minimized and cost function was established in order to optimizing the model′s parameters. Finally, parameters of imaging model were calibrated precisely. Experiment results with quantitive and qualitative comparison show that our method can improve the accuracy of calibration for fisheye lens.