Investigating the Angular and Spectral Properties of Natural Targets Using Chris-Proba Images of San Rossore Test Site

This paper addresses the use of the bidirectional reflectance distribution function (BRDF) of natural surfaces for remote sensing applications and environmental monitoring. Multiangle images, acquired by the compact high resolution imaging spectrometer (CHRIS) over the San Rossore test site, have been analysed in order to exploit the potential of using the BRDF for data mining and precise retrieval of biophysical and geophysical parameters. The apparent reflectance and the anisotropy factor (ANIF) of selected soil cover types have been computed, after correcting the at-sensor radiance for atmospheric effects. The departure of soil reflectance from the standard Lambertian behaviour has been investigated, together with the hypothesis of BRDF spectral-angular separability. Then, the ANIF dependence on surface optical properties, illumination and viewing geometry has been assessed and demonstrated using an ANIF image. The stability of the atmospheric correction procedure was analysed, studying the retrieved reflectance versus the solar zenith angle.