Intensity Correction of Terrestrial Laser Scanning Data by Estimating Laser Transmission Function

Intensity information, recorded by laser scanning, shows great potential for research and applications (e.g., object recognition and registration of images to 3-D models). Multiple studies not only show the significance and possibility of correcting the intensity value but also highlight the existing problems, i.e., that the near-distance and angle-of-incidence effects prevent the practical correction of a terrestrial laser scanner (TLS). In this paper, we explore the near-distance corrections for Z+F Imager5006i, a commercially available coaxial TLS, and propose a corresponding method to correct the range or distance effects on its output intensity data. This method estimates the parameters of customized range-intensity equations using a novel sample data collection design. Using the angle-of-incidence correction method, practical intensity corrections were conducted on TLS point cloud data from white walls and Mogao Grottoes, Dunhuang, China. The results were visualized and show the effectiveness of the proposed method. In addition, we analyzed the new problems that emerge after correction and outline further studies.