回转体形貌测量中的相机自标定  

Camera calibration in morphology measurement of axisymmetric body

作　　者：李雅倩[1] 林洪彬[1] 

机构地区：[1]燕山大学电气工程学院,河北秦皇岛066004

出　　处：《光学精密工程》2011年第8期1957-1963,共7页Optics and Precision Engineering

基　　金：国家科技重大专项资助项目(No.2010ZX04017-013);河北省科学技术研究与发展计划资肋项目(No.10212152);秦皇岛市科学技术研究与发展计划资助项目(No.201001A077)

摘　　要：为实现回转体形貌测量系统的相机自标定,研究了回转体对象的透视投影特性,提出了一种基于被测回转体对象自约束特征的摄像机内、外参数自动标定方法。首先,利用被测场景中回转体截面特征易于提取的特性,从测得图像提取场景中的截面椭圆,利用正交于回转轴的截面椭圆求取圆环点的像,并结合极线约束建立绝对二次曲线像的全约束方程;然后,通过对求取的绝对二次曲线矩阵进行Cholesky分解获得相机的内参数。其次,在求得的内参数矩阵的基础上,通过回转轴和截面图像的成像特点建立测量系统外参数方程,求解测量系统外部参数。实验结果表明,利用本文方法进行相机内参数标定的精度优于0.95%,外参数标定精度优于5.6%。该方法只需利用被测对象自身几何约束,不需任何标定板和标定块,标定过程简单有效,能够满足工程实际需要。To realize the automatic calibration of the camera used in morphology measurement of an axisymmetric body,the perspective projection characteristics of the axisymmetric body were investigated,and a automatic calibration method for intrinsic and extrinsic parameters of the measureing camera was proposed based on self constraint characteristics of measured axisymmetric body.Firstly,by utilizing the extration of section fetures easily,the ellipses in the images of axisymmetric body cross sections were estimated to obtain the images of the circular points.Then,combining with the epipolar constraint,the full constraint equations of the image for an absolute conic were established and computed to obtain the camera intrinsic parameters by Cholesky＇s factorization.Secondly,based on the intrinsic matrix of the camera,the extrinsic parameter equations were established by using the image of the symmetry axis and cross sections to solve the extrinsic parameters.Experimental results indicate that the relative precision of the intrinsic parameters is better than 0.95% and that of the extrinsic parameters is 5.6%.By utilizing only the axisymmetric constraints of the measured object without the calibration plate or block,the calibration process is simple,effective,and can satisfy the real needs.

关 键 词：形貌测量 回转体 标定 圆环点 极线约束 

分 类 号：TP391.4[自动化与计算机技术—计算机应用技术] TP212.12[自动化与计算机技术—计算机科学与技术]