Droacor Topographic Correction Method with Adaptive Diffuse Irradiance Based Shadow Correction

Hyperspectral instruments on UAV systems are increasingly used for extensive and repeated data acquisitions. This paper describes an efficient automatic atmospheric and topographic correction for such instruments. It is based on the DROACOR apparent reflectance outputs for flat terrain, which are further corrected for terrain illumination variations and cast shadows. The correction uses a specific cast shadow detection routine in combination with a semi-empirical estimate of the portion of indirect irradiance on the shaded pixels. Results on three example cases show that ground reflectances can successfully be revealed in shaded areas by the presented method.