Terrain characterization and vegetation structural analysis with full-waveform airborne laser scanners

Full-waveform airborne laser scanning (FWF-ALS) is an active remote sensing technique that records the entire backscattered waveform from transmitted laser pulses. By decomposing the backscatter signals into a series of echoes in a post-processing step, information about the geometric location and radiometric properties of each individual scatterer can be obtained. Even though research on small-footprint waveform data can still be considered to be only in its beginning, a number of benefits start to emerge. From a theoretical point of view, the value of FWF-ALS sensors lies in the fact that the measurement process is depicted in its entire complexity. Thus it is possible to physically model the measurements process. From a practical point of view, the combination of geometric and radiometric information offers new means for interpreting the derived 3D point cloud and for deriving vegetation and terrain information. In this contribution we discuss methods for processing full-waveform ALS data for improving the characterization of the terrain and vegetation structure. The results show that full-waveform information is particularly useful for characterizing low vegetation cover, terrain roughness, and different forest classes. Examples are drawn from study areas in eastern Austria.