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- 2016
投影仪全参数平面线性估计的高精度标定方法
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Abstract:
针对投影仪光路结构复杂、主点偏差大导致高精度标定难以实现的问题,提出一种全参数平面线性估计的方法,为投影仪标定过程提供精确的主点偏差初值,实现了投影仪的全参数高精度标定。首先将投影仪作为虚拟相机,利用多频相移原理得到投影仪和标定板的坐标对应关系,然后采用两步法对非线性方程进行求解计算,通过引入向量参数的方法实现非线性方程的线性化,再利用仿射变换关系选取最优点集,得到稳定的直接参数预估算法,最后利用一种全局捆绑调整算法实现投影仪的高精度标定。采用此方法对投影仪单相机系统完成标定之后,测量了标准球以验证精度,实验表明投影仪单相机系统的平均重投影误差为0？？04像素,测得标准球直径平均偏差小于0.1 mm,球心距偏差小于0.05 mm。结果证明,所提出的投影仪标定方法计算模型简单、稳定性高并具有较高的精度,适用于主点偏差较大和投影仪焦距未知的情况。
To solve the problem that the complex optical path of projector and the large deflection of main point are difficult to meet the requirement of high？？precision calibration, a wholly parametric plane linear estimation algorithm of the projector was put forward to determine the initial deviation value of main point. Thus, the wholly parametric high precision calibration of the projector can be fulfilled. Firstly, the projector is treated as a virtual camera to obtain the coordinates of the projector and the calibration board through multiple frequency phase shift principle. Secondly, a two？？step method is utilized to solve the nonlinear equations. To obtain the stable direct parameter estimation, a vector parameter is introduced to solve the linearization of the nonlinear equation and an optimal point set is selected by affine transformation relationship. Finally, a global bundle adjustment algorithm is developed to implement high precision calibration of the projector. After the calibration of single camera system, the standard balls are measured to verify its accuracy. The experimental results showed that the average value of the projector？？camera system’s re？？projection error is 0.04 pixel, and the average deviation is less than 0.1 mm in diameter and 0.05 mm in distance acquired by the standard balls. The results further indicate that the algorithm model is simple, stable and accurate. Above all, the projector calibration algorithm can be applied to the situation that the displacement of main point has a large deviation and focal length is unknown
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