变焦相机自标定方法研究

Research on Self Calibration Method of Zoom Camera

研究了变焦式相机的标定方法,采用基于二消失点的自标定方法对变焦摄像机的两个固定焦距下的一般参数进行标定,通过与张正友标定方法、机器视觉软件Halcon标定的结果进行比较,验证了该方法的可行性和鲁棒性.为了能够更好地反映变焦相机的变焦特性,建立了能更精确描述变焦摄像机的厚透镜模型.笔者通过对变焦图像进行SIFT特征匹配,根据匹配点对建立直线方程组,采用最小二乘方法估计变焦图像的缩放中心,另外,还计算了不同焦距之间的光心位移.实验结果表明,光心位移与焦距的变化量有明显的差距,从而说明厚透镜模型更适合用来描述摄像机的变焦镜头.

In this paper,the calibration methods of camera zoom is studied. The self calibretion method based on two vanishing points is used to calibrate the general parameters of zoom camera. Compared with the results of two methods of Zhang Zhengyou and the machine vision software Halcon,the feasibility and robustness of the method in this paper is verified. In order to better reflect the characteristics of the zoom camera,a thick lens model selected can describe the zoom camera more accurately. The linear equations can be established according to feature correspondences obtained by the method based on SIFT feature matching between zoom images,and then the zoom center can be identified with the least square method. In addition,the optical center displacement can also be calculated between different focal length. The experimental result shows that the variation between optical center displacement and focal length has a apparent significant gap,so that the thick lens model is more suitable to describe the zoom camera.