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基于单CCD尺寸检测的摄像机标定方法
Camera calibration method of size detection based on single CCD
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作 者:唐亚平 陈苏婷
TANG Yaping, CHEN Suting( 1 Jiangsu Key Laboratory of Meteorological Observation and Signal Processing, Nanjing University of Information Science &Technology, Nanjing 210044)
机构地区:南京信息工程大学江苏省气象探测与信息处理重点实验室,南京210044
出 处:《南京信息工程大学学报:自然科学版》 2014年第6卷第6期 525-529页,共5页
Journal of Nanjing University of Information Science & Technology
基 金:中国博士后科学基金(2011M500940);江苏省高校自然科学研究重大项目(12KJA510001)
摘 要:为提高机械零件尺寸检测的精度,针对Tsai两步标定法中初始参数不精确的问题,提出了基于直线投影约束的三步标定方法。该方法首先利用直线投影约束条件求解出图像中心点和畸变参数的初始值,然后结合径向排列约束条件求解超定方程组得出全部外部参数和余下内部参数值,最后对全局参数进行非线性优化。为验证提出方法的效果,通过建立基于图像模板的世界坐标系实现,即首先利用图像像素坐标求取摄像机坐标,再将摄像机坐标进行归一化,利用外参数矩阵就可以求解出图像点的世界坐标。结果表明,该方法可以有效提高摄像机标定的精度,像素误差可达0.1265像素点,单目视觉尺寸检测中任意两点距离误差小于0.41%。
The problem of inaccurate initial parameters perplexed the Tsai two-step calibration method, hence a three-step calibration method based on linear projection constraints is proposed for camera calibration in order to im-prove the size detection precision of mechanical parts.Firstly,the linear projection constraint conditions were used to solve the initial accurate value of the image center and the distortion parameters.Combined the radial alignment con-straint conditions with overdetermined equations,all the external parameters as well as the rest of internal parameters are then solved.Finally,the nonlinear optimization is conducted to all the parameters by constrained conditions.The world coordinate system based on image template is established to verify the effect of the proposed method.Using the image pixel coordinates, the camera coordinates are calculated and then normalized. The world coordinates corre-sponding to image point are solved using the external parameter matrix. An experiment is carried out with single CCD,and the coordinate results are comparatively analyzed with Tsai method and Zhang method.The experiment re-sults show that this proposed method can effectively improve the accuracy of camera calibration, with pixel error reaching 0-126 5 and distance error of arbitrary two points in monocular visual size detection being less than 0-41%.
关键词:电荷耦合元件(CCD) 摄像机标定 直线约束 径向约束 归一化 Tsai方法
CCD ;camera calibration ;linear constraint ;radial constraint ;normalization ;Tsai method ; |
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