Empirical modeling for non-Lambertian reflectance based on full-waveform laser detection

Abstract. Empirical models are proposed for recalculating non- Lambertian reflectance based on the transmitted pulses and returned pulses that are recorded by a lab-built full-waveform laser detection system. The experiments were implemented on three objects, which were gray-cement concrete, red dull paper, and glazed indoor tile. The pulse energy was calculated based on the pulse waveforms in two ways, integral of the waveform (IW) method and multiplying peak by the full width at half maximum of the waveform (PF) method. The newly introduced empirical parameters semi-ellipsoid distribution ratio (SEDR) of the semi-ellipsoid model and ellipsoid distribution ratio (EDR) of the ellipsoid model were put forward to evaluate the degree of the non-Lambertian reflectance of material surface, instead of Lambertian-based factor that is the cosine of the incidence angle. We conclude that the bigger values of SEDR and EDR indicate more significant deviation from Lambertian for material surface. The modified reflectance results estimated by using the semiellipsoid model display better approximations than those obtained from Phong cosine. Moreover, it is obvious that the modified reflectance using a combined method of PF and modified semi-ellipsoid model outweighs the results estimated by other manners.