Abstract
Terrestrial laser scanning sensors deliver not only three-dimensional geometric information of the scanned objects but also the intensity data of returned laser pulse. Recent studies have demonstrated potential applications of intensity data from Terrestrial Laser Scanning (TLS). However, the distance and incident angle effects distort the TLS raw intensity data. To overcome the distortions, a new intensity correction method by combining the piecewise fitting and overlap-driven adjustment approaches was proposed in this study. The distance effect is eliminated by the piecewise fitting approach. The incident angle effect is eliminated by overlap-driven adjustment using the Oren–Nayar model that employs the surface roughness parameter of the scanned object. The surface roughness parameter at a certain point in an overlapped region of the multi-station scans is estimated by using the raw intensity data from two different stations at the point rather than estimated by averaging the surface roughness at other positions for each kind of object, which eliminates the estimation deviation. Experimental results obtained by using a TLS sensor (Riegl VZ-400i) demonstrate that the proposed method is valid and the deviations of the retrieved reflectance values from those measured by a spectrometer are all less than 3%.
Highlights
During the last two decades, terrestrial laser scanning (TLS), an active remote sensing technique, is one of the most significant means to acquire three-dimensional (3D) point cloud (X, Y, Z) containing high-accuracy and high-density surface topography, which has been widely used in a variety of applications [1,2]
A large number of researchers have focused on data processing algorithms for 3D point clouds, such as the segmentation, classification, and extraction approaches from a mass of point cloud data based on the geometric property of the scanned objects [3,4,5]
The system transmission factor, distance effect and incident angle effect on TLS intensity data should be eliminated so that the intensity data is only related to the physical characteristics of the scanned objects
Summary
During the last two decades, terrestrial laser scanning (TLS), an active remote sensing technique, is one of the most significant means to acquire three-dimensional (3D) point cloud (X, Y, Z) containing high-accuracy and high-density surface topography, which has been widely used in a variety of applications [1,2]. The received power is transformed and recorded as a digital number called “intensity”, which involves the physical characteristics of the scanned object at that point [6]. Some are related to the TLS sensor itself such as the laser wavelength, laser divergence angle and laser power, which can be collectively called as the system transmission factor and considered as a constant. The others are related to the scanned objects including distance, incident angle and physical characteristics of the scanned surface [8,19], which have significant effects on the intensity data and are variable for different scanned objects. The system transmission factor, distance effect and incident angle effect on TLS intensity data should be eliminated so that the intensity data is only related to the physical characteristics of the scanned objects
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
