基于光斑高斯拟合的大视场星相机定焦方法

针对高精度立体测绘任务对星相机的使用要求,提出了一种基于光斑高斯拟合的星相机焦面定焦方法。首先,搭建了基于星点靶标和平行光管的定焦系统,通过移动靶标在中心和边缘视场获取多幅不同程度的离焦图像；其次,采用基于平方加权的质心定位算法计算各视场靶标点像的精确位置用于像面拟合；然后,采用Gibbs采样/马尔可夫蒙特卡洛法对每个光斑进行高斯曲面拟合,获取星点的高斯半径,通过对各视场的最佳焦面位置进行最小二乘拟合,得到最佳像面。对上述定焦方法进行了试验验证,结果表明星相机在各视场的能量集中度测量值与设计值符合,星相机在轨拍摄的星点图像满足要求。

Focus Locating Method on Guassian Fitting of Light Spot for Wide Field Star Camera

Aiming at the requirements of star camera for high precision stereo mapping, a focus locating method based on Guassian fitting of light spot is introduced. Firstly, a focus locating system was built with a point target and a collimator. Several defocused photos were taken by moving the target in central and fringe fields of view. Secondly, an algorithm of centroid locating on squared weighting method was used to calculate the precise location in each field of view to fit the image surface, and an algorithm of Gibbs sampling and Markov Chain Monte Carlo was applied to each light spot to make Guassian curve fitting, to get the Guassian radius of each light spot. Then, the best focal plane was acquired by least squares fitting of the optimum focal planes in each field of view. Tests verify that the enegy focusability in each field of view agrees with the design value, and the pictures taken on orbit meet requirements.