TDI CCD交错拼接推扫相机严格几何模型构建与优化

Establishment and Optimization of Rigorous Geometric Model of Push-broom Camera Using TDI CCD Arranged in an Alternating Pattern

时间延迟积分电荷耦合器件(TDI CCD)交错拼接推扫相机,是指焦平面上交错成两行排列多个TDI CCD阵列,并采用推扫成像方式的光学相机。为兼顾空间分辨率与地面覆盖宽度,当前较多的高分辨率光学遥感卫星都搭载了此类相机。本文总结了此类相机的成像原理和特点,基于成像瞬间多片CCD共享一套外方位元素的特点构建了该类相机的"整体几何模型"。针对定位过程中的外部误差和内部误差,基于整体几何模型设计了相应的内外误差补偿方案,对该类相机几何模型的优化进行了研究。以8片TDI CCD交错拼接的天绘一号(TH-1)卫星高分相机原始影像为试验数据设计了多组试验对本文方法进行验证。结果表明:本文的整体几何模型可严格描述该类相机的原始几何物像关系;仅进行外部误差补偿时,影像定位精度显著提升,但各分片CCD影像残留有不同的系统误差;仅进行内部误差补偿时,影像定位精度没有显著提升,但各分片CCD影像定位精度的一致性得到明显改善;对内部、外部误差均补偿后,影像在X、Y、Z方向的定位精度皆优于2m,且各分片CCD影像定位精度具备一致性;将计算出的内部误差补偿参数应用于成像时间间隔22d的其他多景影像时仍达到了同样的定位精度。

Push-broom cameras using TDI CCD arranged in an alternating pattern are widely carried by typical high-resolution optical satellites in order to obtain high space resolution and enough strip width.For this kind of cameras,several TDI CCD are arranged in an alternating pattern in two lines on the focal plane and push-broom imaging mode is always adopted.Imaging principle and characteristic of this kind of camera is introduced.Exterior parameters of TDI CCD are modeled together based on their same values in any instant of time and an integrated geometric model is finally established.Error compensation methods are designed to remove exterior error and interior error based on this integrated geometric model.A series of tests are designed to verify models and methods proposed in this paper using original image of TH-1Satellite HR Camera whose detectors are divided into 8modules arranged in an alternating pattern.As the results,the imaging geometry of this kind of camera can be rigorously described by this integral geometrical model.The positioning accuracy can be obviously improved by our exterior error compensation method,however,different residual error would be remained for different TDI CCD.The positioning accuracy will not be obviously improved while systematic errors of different TDI CCD can be effectively removed by the interior error compensation method.2mpositioning accuracy in X,Y and Zdirections can be achieved and different systematic errors can be removed when both exterior and interior error were compensated.The same accuracy can be achieved in the other scenes when the calculated inner distortion parameters are adopted.