提出了一种基于场地地表高光谱双向反射分布函数模型的绝对辐射定标方法, 摆脱了对卫星过境时刻同步观测的依赖, 提高了遥感器在轨绝对辐射定标的效率与频次.利用无人机测量系统对敦煌辐射校正场进行了地表方向特性测量, 基于半经验核驱动模型反演了敦煌场地的高光谱双向反射分布函数模型参数.用地表双向反射分布函数模型直接计算的卫星观测方向的地表高光谱反射率数据替代卫星过境时刻场地的地表同步测量数据, 结合中分辨率成像光谱仪大气产品数据, 实现了对Landsat-8卫星的陆地成像仪(OLI)在可见光至近红外波段的高频次绝对辐射定标.Landsat-8/OLI第1~6波段的卫星观测表观辐亮度值与模型计算表观辐亮度值的相对偏差均小于5%, 标准差小于2%.基于无人机场地双向反射分布函数模型的绝对辐射定标方法的定标结果与卫星观测结果具有较高的一致性和稳定性.

An absolute radiometric calibration method based on the surface hyperspectral Bidirectional Reflectance Distribution Function (BRDF) model is proposed, which the efficiency and frequency of on-orbit absolute radiometric calibration of remote sensors are improved by getting rid of the dependence on synchronous observation of satellite overpass time. In-flight high-frequency absolute radiometric calibration verification and application was carried out with Operational Land Imager (OLI) on Landsat-8 using this method. The surface directional reflectance of the Dunhuang test site was measured by the Unmanned Aerial Vehicle (UAV) measurement system, and the hyperspectral BRDF model parameters of the Dunhuang site were inversed based on the semi-empirical kernel-driven model. Comparing the model calculated data with the measured data, the present model is proven to provide a better fit to measured data. The surface hyperspectral reflectance data of satellite observation direction calculated directly by surface BRDF model is used to replace the synchronous measurement data of satellite transit time. The high-frequency absolute radiometric calibration of Landsat-8 OLI is realized by using the reflectance basis method combined with MODIS official atmospheric data products. The relative deviation between the Landsat-8/OLI observed apparent radiance and the model calculated apparent radiance is less than 5% and the standard deviation is less than 2% in the first band to the sixth band. The result shows that the absolute radiometric calibration method based on the UAV BRDF model are in high consistency and stability with the satellite observations.