Surface reflectance retrieval from the intensity data of a terrestrial laser scanner

Abstract

The intensity data recorded by terrestrial laser scanning systems are considered significant measures of the spectral property of scanned objects. These data can be used in an extensive range of object-based applications. However, the direct retrieval of reflectance from intensity information is infeasible because intensity data are influenced by multiple variables, particularly distance and incidence angle. This study proposes a new method to recover the absolute reflectance value of the scanned surface by eliminating the effects of distance and incidence angle. The Faro Focus 120 terrestrial scanner is utilized in the case study. Two sets of experiments are designed to estimate the parameters of the developed model by using Lambertian targets at different reflectance values. With the estimated parameters, the proposed method is applied to recover the reflectance values of natural surfaces. The deviation of the retrieved reflectance values of natural surfaces from the reflectance values measured by a spectrometer is approximately 2.64%. Results show that the proposed method exhibits high accuracy in retrieving reflectance values and can be utilized for actual mapping tasks and geological applications.

Radiometric correction of laser scanning intensity data applied for terrestrial laser scanning

“…This curve shape is very similar to the one obtained previously by Tan et al [46] where the same scanner model, a Faro Focus 3D 120, was used. Along litterature the mid distance behavior generally do not change, at contrary to the short and long distances.…”

“…The scene represents a sculpture of Niki de Saint Phalle, named Arbre-aux-Serpents (Angers, France). As in [46,17], a mean to assess the correction of an heterogeneous point cloud is to select several areas of a same surface or structure, and compare their degrees of variation before and after correction. Results should state about the homogeneity of the correction on each point clouds whatever the point of view.…”

Specular Reflection Effects Elimination in Terrestrial Laser Scanning Intensity Data Using Phong Model

“…Theoretically, surfaces of higher reflectance will reflect a greater portion of the incident laser radiation, thereby increasing the backscattered signal power and further the intensity [1]. Therefore, the intensity is a source of information closely associated with the reflectance properties of the scanned surface [2][3][4]. Intensity, which is insensitive to ambient light and shadowing [5], is initially used to improve point cloud separability.…”

Modeling and Analysis of a Direct Time-of-Flight Sensor Architecture for LiDAR Applications

“…Furthermore, while the physical phenomena related to scattering medium such as fog or cloud will not be discussed, a time-gating feature in the proposed architecture will be discussed in Section 4.4, as a possible way to detect photons is such scenarios, particularly exploiting the advantages in a DTOF sensing method. Figure 1, a pulsed laser with wavelength, λ laser and repetition rate, f laser , is uniformly illuminated over a target scene at distance, d. The target is assumed to be Lambertian in nature, thus, reflecting photons over a diffuse sphere with diameter, d [20,21]. The horizontal and vertical FOV, θ H and θ V respectively, on the target plane are obtained by applying Pythagoras theorem and the corresponding coverage area, A cov , over the scene is then written as,…”