引入灭点约束的TSAI两步法相机标定改进研究

针对TASI两步法相机标定过程无法求解相机主点位置的问题,引入灭点几何约束进行改进,推导并建立了平面格网上两组正交直线透视投影形成的双灭点与相机内参数以及TASI两步法相机标定过程参数间的严格数学关系,详细阐述了综合运用双灭点与径向准直约束计算相机内参数的迭代过程,并以此为基础,给出了相机外方位参数以及径向畸变参数的求解步骤。实验结果验证了该改进方法的有效性。

An Improved Tsai＇s Two-stage Camera Calibration Approach Using Vanish Point Constrain

This paper presents our improvement to the Tsai’s monoview calibration approach with enhanced ability to principle point issues and higher calibration precision is achieved as well.Taking one grid plane as reference object,well-known radial alignment constrain(RAC)is extended to handle with principle point position parameters firstly,though function-dependency between principle point and other parameters are introduced.Next,vanishing points intersected with the perspective projection of grid lines,parallel to world coordinate system X,Y axis respectively,are related to dependent parameters involved in calibration equation from extended RAC and as a result,new non-linear calibration equation with independent parameters is deprived.After that,procedure using improved approach to calibrate camera parameters is specifically listed.In this step,one Least Square based iterative solution is proposed to solve the non-linear calibration equation as well as initial parameter values are given.Finally,stimulated images generated with OpenGL toolkit with known camera parameters and real image from CCD camera Nikon P5100 are used for calibration experiments.Valuable conclusions are conducted.