Topographic and Distance Effects in Laser Scanner Intensity Correction

The effect of incidence angle on the intensity of laser backscatter has been studied in photonics and optics, but the applications of these results to remote sensing of natural land targets are limited, as well as the availability of experimental validation data for airborne and terrestrial laser scanning, where the incidence angle correction using the Lambertian scattering law is common. We have investigated the role of topographic (incidence angle) and distance effects in the radiometric calibration of monostatic terrestrial and airborne laser scanner data. Our results show that the Lambertian (cosine) correction is practically valid at incidence angles up to 20o, whereas at greater angles of incidence, the accuracy of data is still very limited to estimate the performance of any correction method. We also discuss the mixed effects of distance and target reflectance on terrestrial laser scanner intensity calibration, for which the number of applications is constantly increasing. As there are differences in the intensity detectors of different instruments, it is important that the effects of distance and target reflectance are well defined before using any terrestrial laser scanner in intensity measurement. * Corresponding author.