SDGSAT-1多谱段成像仪在轨几何定标方法研究

Study of On-orbit Geometric Calibration of SDGSAT-1 Multispectral Imager

针对SDGSAT-1多谱段成像仪像速异速匹配的特点,提出基于时间对齐约束的在轨几何定标方法。为减少由于多谱段成像仪各片CMOS成像速度不恒定、不一致所造成的同影像行行时不一致对定标造成的不利影响,通过时间对齐约束,采用基于探元指向角和安装矩阵的几何定标模型,综合利用绝对定标和相对定标方法,对SDGSAT-1多谱段成像仪进行在轨几何定标。本文方法能将定标景对地定位误差从定标前约90 km提升至优于0.5像素,配准误差优于0.3像素,测试景对地定位误差优于5像素,配准精度优于0.4像素。和传统方法相比,本文方法能提升绝对定标精度,降低片间拼接误差。实验结果表明,本文方法使多谱段成像仪内外部系统误差得到了精确的标定和补偿,较好地消除了内外几何成像参数误差造成的影响。

Considering characteristics of different CMOS chips images at different speeds of SDGSAT-1 multispectral imager,this paper proposed an on-orbit geometric calibration method based on ground control points used for calibration within the same imaging period.In order to reduce negative influence caused by different CMOS chips imaging speeds which implies different line numbers correspond to different line times,under the constraint of ground control points within the same imaging period,with the imaging model based on detector direction angle and additional matrix,the method used the absolute and relative calibration jointly.The positioning accuracy was improved from 90 kilometers to better than 0.5 pixel and registration accuracy was better than 0.3 pixel in images used for calibration.The positioning accuracy was better than 5 pixels and registration accuracy was better than 0.4 pixel in test images.Compared with classic calibration method,the parameters given by proposed method has a higher positioning accuracy and a better stitching performance between CMOS chips.Results showed that proposed method worked and the positioning accuracy and registration accuracy of multispectral imager were promoted.