Scale integration of bi-directional reflectance effects in remotely sensed vegetated surfaces

Researchers are becoming increasingly aware of the importance of characterising the anisotropic reflectance of vegetated surfaces for remote ground cover monitoring. View angle considerations are particularly important for wide field of view sensors such as the NOAA AVHRR series of instruments. Orbital constraints mean that it is difficult to adequately sample the domain of viewing and illumination geometries in order to build a model of the surface anisotropy. This paper assesses the feasibility of applying a Bidirectional reflectance distribution function (BRDF) derived from high resolution data (30 cm), acquired with an aircraft mounted digital camera, over a number of vegetation classes, to the low resolution (1.1 km) AVHRR observations. The validity of integrating data from these significantly different scales is discussed. Limitations on data comparison due to atmospheric and radiometric effects are also addressed