Analysis of Incidence Angle and Distance Effects on Terrestrial Laser Scanner Intensity: Search for Correction Methods

Abstract

Abstract:The intensity information from terrestrial laser scanners (TLS) has become an important object of study in recent years, and there are an increasing number of applications that would benefit from the addition of calibrated intensity data to the topographic information. In this paper, we study the range and incidence angle effects on the intensity measurements and search for practical correction methods for different TLS instruments and targets. We find that the range (distance) effect is strongly dominated by instrumental factors, whereas the incidence angle effect is mainly caused by the target surface properties. Correction for both effects is possible, but more studies are needed for physical interpretation and more efficient use of intensity data for target characterization.

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

“…However, many confounding variables distort the capability of the original intensity to directly retrieve the target characteristics, of which the instrumental mechanism, atmospheric conditions, target surface properties, and data acquisition geometry plays a significant and dominant role [17,18]. During one campaign period, instrumental configurations are kept constant and atmospheric attenuation can be ignored.…”

A non-destructive technique for health assessment of fire-damaged concrete elements using terrestrial laser scanning

“…(5) is a suitable physical based model under the assumptions mentioned above. However, in reality different relations have been observed between intensity and range for TLS than described by the physical model at near distances due to factors such as instrumental effects [27,33,26,31] causing the physical model to be inapplicable at all scanning distances. Theoretically, the effects of the range and the angle of incidence on the intensity have been found to be independent, implying that it is possible to solve each one of them separately.…”

“…13 and it can be clearly seen that the correction is valid for distances greater than 1m as the rest of the scanning distances investigated follow the theoretical trend where a decreasing course for the intensity is observed over the whole range of scanning distances as the distance increases. Several researchers such as Kaasalainen et al [27] have reported that scanning measurements taken at short ranges of 1m for instance have their intensities reduced in order to avoid overexposure of the scanner's photo-detector. In a similar vein Antilla et al [18] used the HDS6000 scanner and reported that for the first 5m distances, the intensity is reduced so as to keep the level of the intensity within the realm of the sensor's dynamic range and from 5m and above, the intensity roughly follows the range squared inverse as described in the radar range equation.…”

“…The addition of intensity data to the geometric data has proved useful in several applications [19,26,27] and a study by Teza et al [20] showed a successful method based on curvature analysis of TLS geometric data and aimed at recognizing surface defects of a concrete bridge due to mass loss. However, laser scanner intensity data is not often utilised, because it is affected by several factors such as scanning distance and incidence angle, water content, ambient light, humidity, type of laser and object surface properties [21,22].…”

Towards High-Definition 3D Urban Mapping: Road Feature-Based Registration of Mobile Mapping Systems and Aerial Imagery

“…However, the reflected laser signal is significantly affected by the scanning geometry, mainly the distance and the laser incidence angle to the target surface [47][48][49][50]; therefore, it cannot be directly used for road marking extraction. In MMS scanning, where the distance between the scanner and target is relatively close, and the target surface is larger than the footprint of the laser beam, the range dependence can be expressed as 1/R 2 , where R is the range [47]. Another important parameter is the incidence angle.…”