摘要
鉴于透视投影模型在长焦相机标定过程中存在过参数化的问题,采用仿射近似投影模型对长焦相机成像过程进行建模,并提出了基于仿射近似投影模型的长焦相机标定方法。首先,深入分析了仿射投影位姿模糊的形成机制,在此基础上详细推导了仿射近似投影下基于平面模板的长焦相机内外参数解算方法;然后,基于透视投影模型,以重投影像点残差平方和最小为目标函数,对内外参数初值进行优化求精;最后,针对仿射投影模型的位姿模糊,在平面标定模板基础上附加微凸圆柱标志。仿真和实际实验结果显示,所提出的长焦相机标定方法有效可行,在实验室环境下重建平面目标的离面中误差优于0.02 mm。
Objective Featuring unique advantages of high spatial resolution and more detailed information,telephoto cameras have been widely employed in military fields such as aerial reconnaissance,damage assessment,and patrol monitoring,as well as civil fields including industrial precision processing,aerial photogrammetry,deformation monitoring,and traffic surveillance.However,there are practical obstacles to the adoption of telephoto lenses on small-format cameras,with potential difficulties in self-calibration.A telephoto lens will inevitably narrow the field of view(FOV),exerting detrimental effects on the performance of the central perspective projection model,which will result in overparameterization,ill-conditioning,and subsequent numerical instability in normal equations of the bundle adjustment.Linear dependencies between the intrinsic and extrinsic parameters make it rather difficult to recover satisfactory calibration parameters in such weak geometry conditions.Therefore,an alternative affine approximation of the perspective projection model is adopted to accommodate high-accuracy and close-range photogrammetry with telephoto lenses,which makes full use of the advantages of the model,such as high linearity,simplicity,and high robustness.Additionally,a calibration method of telephoto cameras based on the affine approximation projection model is proposed.By employing the proposed model,this paper aims to obtain better calibration performance of telephoto cameras,thereby laying a foundation for the application of telephoto cameras.Methods As the most common affine approximation of the perspective projection model,the characteristics of weak perspective and paraperspective projection are thoroughly elaborated,according to which a calibration method of telephoto camera based on the affine approximation projection model is built.In this paper,the formation mechanism of reversal ambiguity is thoroughly analyzed,and the estimation method of calibration parameters based on the planar template under the affine approximat
作者
孙聪
马艳
张国龙
高奕
于起峰
Sun Cong;Ma Yan;Zhang Guolong;Gao Yi;Yu Qifeng(State Key Laboratory of Astronautic Dynamics,Xi'an Satellite Control Center,Xi'an 710043,Shaanxi,China;College of Aeronautics and Astronautics,National University of Defense Technology,Changsha 410073,Hunan,China)
出处
《光学学报》
EI
CAS
CSCD
北大核心
2023年第4期85-95,共11页
Acta Optica Sinica
基金
国家自然科学基金重大科研仪器研制项目(11727804)。
关键词
测量
长焦相机
相机标定
仿射近似投影
位姿模糊
measurement
telephoto camera
camera calibration
affine approximation projection
pose ambiguity
