Reflectance anisotropy is a signal that contains information on the optical and structural properties of vegetation and other surfaces and can be studied by performing multi-angular reflectance measurements that are often done using cumbersome goniometric measurements.
A research team of the UARSF have recently published a paper in Remote Sensing in which they describe an innovative and fast method using a hyperspectral pushbroom spectrometer (HYMSY) mounted on a multirotor unmanned aerial vehicle (UAV) to perform such multi-angular measurements. By hovering the UAV above a surface while rotating it around its vertical axis, they were able to sample the reflectance anisotropy within the field of view of the spectrometer, covering all view azimuth directions up to a 30° view zenith angle. They used this method to study the reflectance anisotropy of barley, potato, and winter wheat at different growth stages. The results of this study indicate that the presented method is capable of retrieving anisotropic reflectance characteristics of vegetation canopies and that it is a feasible alternative for field goniometer measurements.
Full-text version of the paper can be found at: