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Comparison of three airborne laser bathymetry data sets for
monitoring the German Baltic Sea Coast
Yujin Song* 3 , Joachim Niemeyer 3 , Wilfried Ellmer b , Uwe Soergel c , Christian Heipke 3
institute of Photogrammetry and Geoinformation, Leibniz Universität Hannover, Nienburger Str.l,
30167 Hannover, Germany;
b Federal Maritime and Hydrographic Agency, Neptunallee 5, 18057 Rostock, Germany;
institute of Geodesy, Technische Universität Darmstadt, Franziska-Braun-Str.7, 64287 Darmstadt,
Germany
ABSTRACT
Airborne laser bathymetry (ALB) can be used for hydrographic surveying with relative high resolution in shallow water.
In this paper, we examine the applicability of this technique based on three flight campaigns. These were conducted
between 2012 and 2014 close to the island of Poel in the German Baltic Sea. The first data set was acquired by a Riegl
VQ-820-G sensor in November 2012. The second and third data sets were acquired by a Chiroptera sensor of Airborne
Hydrography AB in September 2013 and May 2014, respectively. We examine the 3D points classified as seabed under
different conditions during data acquisition, e.g. the turbidity level of the water and the flight altitude. The analysis
comprises the point distribution, point density, and the area coverage in several depth levels. In addition, we determine
the vertical accuracy of the 3D seabed points by computing differences to echo sounding data. Finally, the results of the
three flight campaigns are compared to each other and analyzed with respect to the different conditions during data
acquisition. For each campaign only small differences in elevation between the laser and the echo sounding data set are
observed. The ALB results satisfy the requirements of IHO Standards for Hydrographic Surveys (S-44) Order lb for
several depth intervals.
Keywords: Airborne laser bathymetry (ALB), 3D point cloud, Secchi depth, coastal, accuracy
1. INTRODUCTION
An accurate description of the seabed is essential for enabling a precise and safe navigation of ships as well as a reliable
coastal monitoring and management. To measure the water depth and shape of the seabed various ship-based remote
sensing techniques such as single-beam echo sounder, multi-beam echo sounder and side-scan sonar have been
developed. However, data acquisition using these traditional methods for surveying the seabed topography is both costly
and time consuming. Furthermore, it is difficult to obtain such information in shallow water zones because these areas
are often not accessible for vessels. A solution to cope with these issues is to use airborne laser bathymetry (ALB). This
measurement technique is particularly suitable for data acquisition in shallow water zones, and it is able to provide
continuously topographic data of both, land surface and shallow water zones. ALB is well suited for nearshore mapping
because it provides 3D point data needed for a variety of purposes, e.g. navigation, nautical charting, shore protection,
coastal structure evaluation, and emergency response [1, 2].
In this paper, we report on practical experience gained in the project ‘Investigation in the use of airborne laser
bathymetry in hydrographic surveying’, in which the applicability of ALB for monitoring the German Baltic Sea Coast is
analyzed in cooperation with the German Federal Maritime and Hydrographic Agency. Between 2012 and 2014, three
flight campaigns were performed close to the island of Poel. We evaluate the 3D points classified as seabed in order to
investigate the accuracy of the different sensors and the impact of environmental parameters.
2. AIRBORNE LASER BATHYMETRY
Airborne laser bathymetry (ALB) sensors usually emit green laser pulses (e.g. wavelength /. = 532 nm) for the
bathymetric measurement. This wavelength is able to penetrate the water column and is reflected from the seabed.
Additionally, most sensors use a second wavelength in the infrared part of the spectrum (e.g. X = 1064 nm) for the
topographic and water surface measurements. The infrared laser pulse is reflected from the water surface. As a result the
Remote Sensing of the Ocean, Sea Ice, Coastal Waters, and Large Water Regions 2015, edited by
Charles R. Bostater, Stelios P. Mertikas, Xavier Neyt, Proc. of SPIE Vol. 9638, 96380Z
©2015 SPIE ■ CCC code: 0277-786X/15/$18 ■ doi: 10.1117/12.2194960
Proc. of SPIE Vol. 9638 96380Z-1
