Improved reflectance calculation in full-waveform LiDAR considering the angle of incidence

Abstract. Reflectance is a widely used feature for all types laser scanning data. Thus, the accuracy and improvement of the reflectance parameter is a persistent topic of research. For short laser pulses with medium-sized footprints, previous work has investigated the effects of inclined targets on the recorded waveform of full-waveform LiDAR systems. In this work, a new methods to extract incidence angle from only a single waveform can be leveraged to improve reflectance values through recalculation based on the laser-radar equation and correcting for angle of incidence artifacts. The results of the proposed method are evaluated with two datasets based on two different topo-bathymtric laser scanners. For both systems, we calculated the relative biconical reflectance and relative averaged bidirectional reflectance distribution function (rBRDF) and evaluated them on homogeneous roof faces. The two reflectance measures are then compared to the initial reflectance values of the laser scanners used in the study. Both measures showed improvements compared to the standard values. The biconical reflectance shows the best overall mean score for all surveyed roofs with an median absolute devation improvement of 0.80 dB to 0.62 dB for the RIEGL VQ-880-GII and 0.61 dB to 0.56 dB for the RIEGL VQ-1560i-DW. In addition the rBRDF also displays an improvement with varying results depending on the deployed system. These results highlight the advantages of the proposed reflectance measures and the potential improvement of the widely used LiDAR attribute.