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

Sanna Kaasalainen,Anssi Krooks,Anttoni Jaakkola,Antero Kukko,Mikko Kaasalainen

doi:10.3390/rs3102207

Sanna Kaasalainen, Anssi Krooks + Show 3 more

Open Access

https://doi.org/10.3390/rs3102207

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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.

Highlights

The signal received by a LiDAR detector is mainly affected by four essential factors: instrumental and atmospheric effects, the target scattering characteristics, and the measurement geometry
We have investigated the radiometric calibration of terrestrial laser scanners (TLS) intensity [13], and the incidence angle and distance effects on the intensity [12,22,28]
We have studied the range and incidence angle effects on the intensity measurement and radiometric calibration for different terrestrial laser scanners to establish a correction scheme for both of these effects

Summary

Introduction

The signal received by a LiDAR detector is mainly affected by four essential factors: instrumental and atmospheric effects, the target scattering characteristics, and the measurement geometry. 2011, 3 equation summarizes all the parameters relevant to describe these effects and the power of the backscattered signal in a laser scanner detector [1]. Σ is the backscatter cross section: it describes the scattering of a wave from an object. The power of the backscattered signal is inversely proportional to R2 for homogeneous targets spreading over the entire laser footprint (these are called extended targets [1]). For linear objects and individual large scatterers, the intensity is proportional to R3 and R4 respectively [1,2]

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Conclusion