遥感25号无场化相对辐射定标

摘要

遥感25号是中国首颗高敏捷亚米级高分辨率光学遥感卫星.常规的偏航相对辐射定标利用卫星或相机偏航90°对地面均匀场进行成像,使得传感器所有探元获取相同的入瞳辐射亮度,实现卫星传感器的相对辐射定标.但拍摄单一地物均匀场并不能实现卫星传感器全动态范围的辐射定标,并降低了该方案的应用效率.本文针对中国遥感25号卫星,提出了不依赖于地面均匀场的无场化偏航辐射定标方法实现遥感25号的高精度高频次相对辐射定标;同时在偏航辐射定标数据处理中提出基于line segment detector(LSD)算法偏航定标数据规定化方法,确保偏航辐射定标图像每一行数据为传感器所有探元对同一地物的成像;采用传感器探元直方图规定化的方法实现遥感25号全动态范围相对辐射定标参数解算.利用遥感25号偏航辐射定标数据进行辐射定标试验并与传统在轨统计辐射定标进行对比,结果表明遥感25号经偏航辐射定标后所有探元平均条纹系数优于0.07%,图像上各种条纹条带噪声以及残余条带噪声得到较好去除,无场化偏航辐射定标方法优于传统在轨统计辐射定标方法.%YG-25 is the first agility optical remote sensing satellite of China to acquire the sub-meter imagery of the earth.The side slither calibration technique is an on-orbit maneuver that has been used to flat-field image data acquired over the uniform calibration field.However, imaging to the single uniform calibration field cannot afford to calibrate the full dynamic response range of the sensor and reduces the efficiency.The paper proposes a new relative radiometric calibration method that a 90-degree yaw maneuver is performed over any non-uniform features of the Earth for YG-25.Meanwhile, we use an enhanced side slither image horizontal correction method based on line segment detector(LSD)algorithm to solve the side slither image over-shifted problem.The shifted results are compared with other horizontal correction method.The histogram match algorithm is used to calculate the relative gains of all detectors.The correctness and validity of the proposed method are validated by using the YG-25 on-board side slither data.The results prove that the mean streaking metrics of relative correction images of YG-25 is better 0.07%, the noticeable striping artifact and residual noise are removed, the calibration accuracy of side slither technique based on non-uniform features is superior to life image statistics of sensor's life span.