坐标反变换即根据已知的物方坐标求其像方坐标的过程,是线阵推扫式影像几何处理的重要计算环节。对于时间延迟积分电荷耦合器件(time delay integration charge coupled devices,TDICCD)推扫影像,由于行积分时间跳变,若直接基于共线方程模型进行坐标反变换计算,不仅迭代次数多,在某些情况下还会出现不收敛的情况;利用有理多项式模型等通用成像几何模型替代其共线方程模型时,又存在拟合精度不高难以满足实际要求的问题。对此,本文提出了一种基于虚拟扫描行的TDICCD推扫影像坐标反变换方法,巧妙地解决了TDICCD推扫影像坐标反变换的效率和精度问题,利用国产资源卫星进行实验验证了此方法的正确性和可行性。
A coordinate inverse transform (CIT) calculates the image-space coordinates of a corresponding ground point, and is substantially important for the processing of linear array pushbroom images. One of the imaging characteristics of a TDI CCD pushbroom sensor is that the scanline integration time fluctuates. CIT is performed on TDI CCD pushbroom images, based on its collinearity equations; the process will iterate several times, and even then sometimes, no convergent results are available. Since the fluctuation of integration time also affects the alternative accuracy of generic imaging models such as the rational function model (RFM), the accuracy of CIT based on the RFM of TDI CCD pushbroom images can be hardly guaranteed. Hence, this paper proposes a novel method for a CIT of TDI CCD pushbroom images based on virtual image scanline, solving the problem of low effi- ciency and accuracy when calculating image-space coordinates. Experiments tested on the TDI CCD pushbroom images from a domestic resource satellite demonstrate the correctness and feasibility of our method.