光测轨检系统的高精度摄像机标定

High precision camera calibration method of track inspection system

将靶标设定为一个辅助平面,建立辅助平面坐标系进行2步标定:第1步求取靶标面与像平面的对应透视关系;第2步求取空间坐标系与辅助平面坐标系的透视关系。研究结果表明:相对于传统标定法,该方法同时考虑径向畸变和切向畸变,提高了目标点定位精度;建立隐式数学模型而非直接标定摄像机内外参数,简化了标定。且将畸变量包含与隐式方程中不用实际求出畸变量,所以不要求靶标与摄像机成特殊位置;两步均用最小二乘法快速求解线性方程,简便快速;采用对特征圆标号的高精度标定模板,特征圆心可以精准提取,标定图像有较高的鲁棒性。

The method sets a assistant plane and establishes coordination on it. The process is divided into tow steps. The first step gets corresponding perspective relation between target plane and imaging plane. The second step gets perspective relation between assistant plane coordinate system and space coordinate system. By compa- ring with the traditional camera calibration methods, the method mentioned here takes full account of radial and tangential distortion to improve the location accuracy. To simplify the calibration, implicit model was used instead of calibrating parameters of the camera directly. The method does not consider distortion rather than embody the distortion in equation, that means the camera and the target must not be placed in special location. Step two does not refer to distortion. It is simple and fast to solve linear equations by using least squares. Using a special kind of central target, features can be extracted and the images of calibration have a high robustness.