成像仿真是相机研制必不可缺的步骤。航空线阵摆扫式相机具有距离远、成像倾角大的特点,容易导致成像仿真过程中坐标投影计算迭代不收敛。针对这一问题,提出一种视向量分段迭代的坐标投影计算方法。首先将迭代窗口内的视向量进行分段,根据像点坐标和其所在扫描行的外方位元素计算各分段处的高程与对应的地面点的高程之差,寻找差值最小的分段;然后在该分段处继续构建迭代窗口进行计算,直至高程差值的最小值小于给定的阈值,得到像点坐标对应的地面点三维坐标;最后将该地面点对应的正射影像上的灰度值赋予模拟影像的像点,生成仿真影像。通过三组不同地形的实验数据成像仿真结果表明,该方法成像仿真的精度高于0.005 pixel,且其稳健性较高,能够适用于大倾角成像方式的成像仿真。

Imaging simulation is an essential step in camera development. The aerial linear whiskbroom camera has the characteristics of long distance and large imaging angle, which easily leads to the coordinate projection calculation in the imaging simulation process is iteratively non-convergence. To solve this problem, a new iterative coordinate projection calculation method based on visual vector segmentation is proposed. Firstly, the visual vector is segmented in the iteration window, and then the elevation difference between each segmentation and the corresponding ground point is calculated according to the coordinates of the image point and the exterior orientation element of the scan line. The segmentation of minimum elevation difference is found. Then the iterative window continually built at the segmentation is calculated until the minimum elevation difference is less than the given threshold, thus the image coordinates corresponding to three-dimensional coordinates of the ground point are obtained. Finally, the gray value of the orthographic image is given to the simulated pixel point corresponding to the ground point to generate simulation images. The imaging simulation results of the experimental data from three different terrains show that the accuracy of this imaging simulation method is higher than 0.005 pixel. Its robustness is higher and it can be applied to the imaging simulation of large-angle imaging method.