MOBILE MAPPING AND THE USE OF BACKSCATTER DATA FOR THE MODELLING OF INTERTIDAL ZONES OF BEACHES.

Mobile mapping with laser scanning is frequently limited to the sole geometric reconstruction of objects or surfaces. In the special case of the construction of Digital Elevation Models (DEMs) of intertidal zone of beaches, this task is known to be very challenging. In the context of the interdisciplinary research project named 'SeArch', which aims at documenting and managing archaeological patrimony in the North Sea, a field campaign was organized in the summer of 2013. During this campaign, an amphibious vehicle (ARGO) was equipped with a Terrestrial Laser Scanner (TLS) in profiler mode, an Inertial Measurement Unit (IMU), a Real-Time Kinematic Global Navigation Satellite System (RTK GNSS) and a PC hydrographic data acquisition software and huge storage capacity. Based on previous research, this configuration appeared to have the best performance under the environmental conditions at the Belgian North Sea coast. Especially for the intertidal zones of beaches, the use of this mobile platform resulted in very promising results from a geometrical point of view. A summary of the results of the campaign is presented in this paper. Although the focus of this campaign was on the construction of DEMs with a high resolution and a high accuracy, the used Leica HDS 6200 phase-based laser scanner also returned a backscatter value for each measured point. A provisional analysis of these values suggested a relation between the physical properties of the reflecting surface and the registered backscatter values. However, earlier studies have also demonstrated the influence of the incidence angle and measured distance on this backscatter value. As will be discussed in this paper, a correction function can be defined that takes these parameters into account as weights for corrected backscatter data. In combination with the commonly used point cloud, the corrected values allow the calculation of false-color composites of the measured surface and the detection and description of features. [ABSTRACT FROM AUTHOR]