The coastal environment is particularly subject to the effects of the climate change.It is thus necessary to survey frequent its evolution to preserve it. In this context, the Airborne Laser Scanning (ALS) is a powerful tool that offers the possibility to survey very large areas with repeatable and regular acquisitions with a high spatial resolution. Along with the discrete topography measurements, the ALS backscattered intensity by the coastal surfaces is also acquired. This data, not fully yet studied in the litterature, provides new information characterizing the scanned surfaces. However, they are very much influenced by the variable incidence angle of the laser shots from the plane. The behavior of the intensity reflected by the surface flown according to the incidence angle is analyzed using the microfacets distribution model. The results showed that, in coastal environments, three surface types have distinct behaviors: (i) the water surfaces reflecting specularly the incident beam, (ii) highly diffuse sandy surfaces, (iii) and higly water-saturated sandy areas combining specular and diffuse mechanisms. For the unsaturated sandy surfaces, studies demonstrated that (i) the granulometry, for the fine to very coarse sand, does not influence the backscattered intensity and (ii) a empirically law allows to link the moisture factor to the intensity.
Analysis of Airborne Laser Scanning intensity in sandy coastal environments