辐射定标是光学遥感卫星数据定量化应用的关键技术之一。提出了基于亚像元目标的高分辨率光学遥感卫星在轨辐射定标方法,以反射点源作为参照目标,并以地面同步测量为主,通过简化辐射传输的计算过程获取大气透过率与遥感器入瞳辐亮度;根据多能量等级的亚像元目标设置与系统点扩展函数检测结果,将亚像元目标辐射与程辐射、地气耦合辐射及背景辐射有效分离;突破时空及天气条件限制,在复杂环境条件下实现光学遥感卫星全动态范围的高精度定标。实验结果表明,基于亚像元目标的高分辨率光学遥感卫星在轨辐射定标不确定度优于3.2%,与基于大面积多反射率灰阶靶标的定标结果相差3%;这种轻小型的亚像元目标适应于光学遥感卫星的高频次定标应用需求。

Radiometric calibration is one of the key technologies for quantitative application of optical remote sensing satellite data. This study proposes an on-orbit radiometric calibration approach for a high-resolution optical remote sensing satellite based on sub-pixel targets. The detection reference is the reflected point source, and the ground synchronization measurement is mainly used. Atmospheric transmittance and incident pupil radiance are obtained by simplifying radiometric transfer calculation. The method can also effectively isolate the response of a remote sensing image created by sub-pixel targets from the response produced by sky path radiance, ground-atmospheric coupled radiance, and background radiance, according to multi-energy sub-pixel target setting and on-orbit point spread function detection results. The approach can break the limit of time, locale, and weather conditions and achieve high precision calibration for the optical remote sensing satellite with a full dynamic range in complex environments. Results show that calibration uncertainty for the high-resolution optical remote sensing satellite based on sub-pixel targets is lower than 3.2%. Moreover, the calibration result of the proposed method is different from that of the gray-scale target method by 3%. A small and light sub-pixel target can satisfy the high frequency on-orbit calibration application of the optical sensing satellite.