针对山区遥感影像计算雪面反射率的难点,采用各向异性校正与地形校正相结合的方法,将研究区不同坡面方向的雪面反射率归一化至平坦地表垂直观测方向上的雪面反射率,以消除地形影响.其中,各向异性校正采用二向反射分布函数(Bidirectional Reflectance Distribution Function,BRDF)模型;地形校正采用山地辐射传输模型.遥感影像选用新疆玛纳斯河流域的高分一号卫星(GF-1)宽幅相机数据.利用同步观测的积雪光谱数据对此方法的校正能力进行验证,结果表明此方法能够消除大部分地形和大气的影响;计算的雪面反射率在非阴影区与阴影区均与实测数据相一致;该方法可为山区积雪的光学遥感研究提供技术支撑.
Aiming at the difficulty in calculating snow reflectance from high spatial resolution image in mountain areas,a method combined with anisotropy correction and topographic correction was proposed to covert the snow reflectance in different slope to the nadir direction on the flat surface.In the process of anisotropy correction and topographic correction,BRDF model and mountain radiation transmission model were applied to eliminate topographic effects respectively.The GF-1 WFV image of Manasi River Basin,Xinjiang Province was chosen as research data and snow spectral data achieved by synchronous observation was employed to evaluate the this method.The results showthat this method could generally eliminate the influence caused by rugged terrain and atmosphere,and the snow reflectance calculated by this method was in agreement with field observations in both non-shadow area and shadow area.This method can support the research on optical remote sensing of snow in mountain areas.