Intensity data correction based on incidence angle and distance for terrestrial laser scanner

Terrestrial laser scanning (TLS) systems not only convey geometric information but also deliver backscattered intensity data of the scanned targets, which are generally acknowledged as significant observations that involve target reflectance information. Numerous studies have shown the potential of TLS intensity in many applications. However, directly using original intensity data is not recommended because of the existence of radiometric system variations, scan geometry discrepancies, environmental differences, and other factors. Performing radiometric correction is, therefore, indispensable to fully eliminate these effects and to compute target reflectance as accurately as possible. In this study, we investigate the effects of incidence angle and distance on intensity measurements and propose a practical method to eliminate the two effects for different TLS instruments. The results show that incidence angle and distance significantly influence TLS intensity data, and the proposed model with versatility can accurately correct the laser intensity value to eliminate the effects of incidence angle and distance.