海洋一号C卫星海岸带成像仪在轨几何定标

On-orbit geometric calibration of HY-1C satellite coastal zone imager

海洋一号C卫星(HY-1C)搭载的海岸带成像仪(coastal zone imager,CZI)为满足大幅宽成像需求,采用双相机组合成像,每台相间使用2片4色电荷耦合光敏元器件(charge-coupled device,CCD)拼接。从严密几何成像模型出发,对相机成像过程中存在的系统误差进行分析,采用一种基于探元指向角的几何定标模型,并结合CZI相机设计特点与几何特性,设计出一套针对HY-1C/CZI的几何定标方案。首先利用CZI参考基准波段影像与高精度参考影像进行绝对几何定标,采用分步迭代的方法对参考基准波段影像内外定标参数进行解算,其次进行波段间相对几何定标,最后得到所有波段影像的几何定标结果。实验结果表明,经在轨几何定标后,平面无控定位精度优于5个像元,影像几何质量得到明显改善,说明所采用的定标模型和方案合理有效。

In order to meet the requirements of wide-width imaging,the coastal zone imager(CZI)onboard HY-1C satellite adopts the combination of two cameras for imaging and splices two 4-color charge-coupled devices(CCD)between single phase.Based on the rigorous geometric imaging model,this paper analyzes the systematic errors existing in the imaging process of the camera,adopts a geometric calibration model based on the directional angle of probe,and designs a geometric calibration scheme for the CZI camera based on the design of camera characteristics and geometric characteristics.CZI reference band images and high-precision reference images are used to carry out absolute calibration,and the internal and external calibration parameters of reference band images are calculated by step iterative method.According to the bands’constraint relation,the calibration results of non-reference band images are obtained by relative calibration between bands.The experimental results show that,the positioning accuracy of plane-free control points is better than 5 pixels after on-orbit geometric calibration,and the geometric quality of the images is obviously improved,which indicates that the calibration model and scheme adopted in this paper are reasonable and effective.