球形靶标中心成像点的高精度定位

为提高球形靶标中心在像平面上成像点的定位精度,研究了球形靶标成像理论及球心成像点定位方法。建立了空间球在摄像机系统下的投影模型,结合空间解析几何理论,证明了球形靶标的透视投影特性。推导出了球心成像点坐标的精确表达式,并结合测量实际给提出了球心成像点的高精度定位方法。利用仿真实验建立了球心投影畸变误差模型并分析了相关影响因素。最后,结合陶瓷标准球进行了视觉系统位姿参数标定实验。结果表明,该定位方法求得的空间球球心重投影误差比传统的球心成像坐标定位方法产生的重投影误差平均减少了36%,位姿参数稳定性相对提高了40%。得到的结果验证了该球形靶标中心成像点定位方法精度高,鲁棒性强,可应用于基于球形靶标的视觉标定或测量中。

High-precision positioning of projected point of spherical target center

To improve the positioning precision of the projected point for a spherical target center, the imaging theory of spherical target and positioning method of the spherical target center were investigated. By establishing the imaging model of spherical target and combining spatial analytic geometry theory, the perspective projection properties of spherical target were verified and an exact expression for the position of projection point of sphere center was deduced. Finally, by combining with an actual measurement, the precision positioning method for the projected point of spherical target center was given. Furthermore, an error model for projected spherical central distortion was established on the basis of the simulation experiment, and corresponding effect factors were analyzed. With the use of a ceramic standard ball, calibration experiments of the pose parameters of a vision system were implemented. It shows that the re-projected error of the spherical target center from the proposed method has less 36% averagely than that of the traditional method, and the stability of the pose parameters is increased by 40% relatively. These results verify that the proposed positioning method for the projected point of spherical target center has high precision and robustness, and it can be widely used in visual calibration or measurement based on spherical targets.