基于图像特征分布优化的相机外参自标定  

External parameter calibration based on image feature distribution optimization

作　　者：王宗盛 苏志龙 韩永胜[3] 关棒磊 张东升[1,2] 于起峰 WANG ZongSheng;SU ZhiLong;HAN YongSheng;GUAN BangLei;ZHANG DongSheng;YU QiFeng(School of Mechanics and Engineering Science,Shanghai University,Shanghai 200444,China;Shanghai Key Laboratory of Mechanics in Energy Engineering,Shanghai Institute of Applied Mathematics and Mechanics,Shanghai 200444,China;Department of Water Conservancy Engineering,Shandong Water Conservancy Vocational College,Rizhao 276826,China;Hunan Provincial Key Laboratory of Image Measurement and Vision Navigation,College of Aerospace Science and Engineering,National University of Defense Technology,Changsha 410073,China)

机构地区：[1]上海大学力学与工程科学学院,上海200444 [2]上海市应用数学与力学研究所,上海市能源力学重点实验室,上海200444 [3]山东水利职业学院水利工程系,日照276826 [4]国防科技大学空天科学学院,图像测量与视觉导航湖南省重点实验室,长沙410073

出　　处：《中国科学：技术科学》2021年第11期1410-1418,共9页Scientia Sinica(Technologica)

基　　金：国家重点研发计划(编号:2018YFF01014200);国家自然科学基金(批准号:12002197,12072184,11727804);中国博士后科学基金第67批面上资助(编号:2020M671070);上海市“超级博士后”计划(编号:2019192)资助项目。

摘　　要：标定两个已知相机之间的相对外参是三维视觉变形测量中的一个基本任务.当使用自标定技术时,一般需要在标定图像中建立立体对应关系,而实际测量场景中复杂的纹理分布对可靠立体特征的建立提出了挑战.为此,本文通过研究图像特征分布的优化策略,提出了一种针对实际测量任务的非约束场景外参标定方法.首先,通过图像特征匹配获得立体图像间的点匹配信息,并利用图像相关算法进行筛选,建立一组可靠的立体点对应关系,从而通过求解本质矩阵得到相机间的外参估计.随后,以重投影误差作为标定精度评估指标,提出一种特征点稀疏和循环补充策略,可对单帧或者多帧图像的特征点分布进行优化,有效实现对标定误差的补偿.实验表明本文的标定算法具有良好的精度和鲁棒性.External parameter calibration between two known cameras is a fundamental task in three-dimensional visual deformation measurement.The self-calibration technique requires the establishment of stereo correspondences in the calibration images;however,the complex distribution of textures in real scenes poses a great challenge to the development of reliable stereo correspondences.This paper proposes a non-constrained external parameter calibration method for actual measurement tasks by studying the optimization strategy of image feature distribution.First,the correspondences between stereo images are obtained through feature-matching,and an image correlation algorithm is adopted to screen outliers for establishing a set of reliable stereo correspondences.External parameter estimation between two cameras is then achieved by solving the essential matrix.A feature-point sparse and recurrent supplemental strategy using the reprojection error as the metric of calibration accuracy is proposed.This strategy can optimize the feature distribution of single or multiple frames,thereby effectively realizing calibration error compensation.Experiments show that the calibration algorithm proposed in this paper has good accuracy and robustness.

关 键 词：相机标定 极线约束 数字图像相关 特征匹配 

分 类 号：TP391.41[自动化与计算机技术—计算机应用技术]