In: Wagner W., Szekely, B. (eds.): ISPRS TC VII Symposium - 100 Years ISPRS, Vienna, Austria, July 5-7, 2010, IAPRS, Vol. XXXVIII, Part 7B 
EVALUATION OF A LASER LAND-BASED MOBILE MAPPING SYSTEM FOR 
MONITORING SANDY COASTS 
M. Bitenc a , R. Lindenbergh b , K. Khoshelham b and A.P. van Waarden c 
a Geodetic Institute of Slovenia, Jamova 2, 1000 Ljubljana, Slovenia - Maja.Bitenc@gis.s 
b Delft University of Technology, Dept, of Remote Sensing, Kluyverweg 1, 2629 HS, Delft, Netherlands 
- (r.c.lindenbergh, K.KhoshElham)@tudelft.nl 
c Dutch Ministry of Public Works and Water Management, Data ICT Dienst, Derde Werelddreef 1, 2622 HA, Delft, Netherlands 
- pieter.van.waarden@rws.nl 
Commission VII Symposium 2010 
KEY WORDS: Coast, Hazards, Mapping, DEM/DTM, Laser scanning, Mobile, Quality 
ABSTRACT: 
The Dutch coast is characterized by sandy beaches flanked by dunes. Its morphology is essential for the defense against flooding of 
the hinterland. Therefore it is monitored on a yearly basis by Airborne Laser Scanning (ALS). However, it is recognized that most 
erosion of the beach and first dune row takes place during storms. To assess the state of the coast immediately after a storm with 
ALS is expensive and difficult to organize. Here, the performance of a Land-based Mobile Mapping System (LMMS) is evaluated. 
A test data set was obtained by Geomaat using the StreetMapper LMMS system, employing three individual line scanners. Both the 
relative quality of laser point heights and of a derived Digital Terrain model (DTM) are assessed. In the first analysis height differences 
between close-by points are considered. Except for arbitrary close-by points, also close-by points obtained from different scanners and 
from different drive-lines are analyzed. It is shown that on a flat beach a precision of 3 mm is achieved and that almost no internal 
biases exist. In the second analysis a DTM with a grid size of 1 m is obtained using least squares. Each grid point height includes a 
quality description, which incorporates both measurement precision and terrain roughness. Although some problems remain with the 
low scanning height of 2 m, which causes shadow-effect behind low dunes, it is concluded that a laser LMMS enables the acquisition 
of a high quality DTM product, which is available within two days. 
1 INTRODUCTION 
The Dutch coast typically consists of a relatively flat sandy beach 
lined on a side by the dunes, which are partly covered by mar 
ram grass. This coastal area is important for the Netherlands for 
many reasons, e.g. as recreational and nature area, and as pro 
tection against a sea flood and storms. The last usage is espe 
cially crucial, because the most densely populated areas in the 
Netherlands are located just behind the coastal defense and are 
partly below the mean sea level. Therefore, it is essential to con 
tinuously monitor and maintain the coast in order to protect the 
Dutch hinterland from the sea. In 1990 a national coastal policy 
was adopted, with the aim of maintaining the seaward position 
of the coastline, as it was on January 1, 1990. To successfully 
maintain this so-called Basal Coast Line a suitable acquisition 
technique to measure beach morphology and its changes needs to 
be employed. Because high energy events like storms may cause 
large changes, as for example shown in Fig. 1, the main inter 
est is to monitor coastal topography on the temporal and spatial 
scale of storm impacts. Therefore, a flexible system is needed that 
can access a damaged area immediately after the storm and pro 
vide the results of morphologic changes as quickly as possible (in 
one day). Besides, to estimate in detail the beach erosion caused 
by heavy storm events, high spatial resolution measurements are 
needed. 
Since 1996 the Dutch Ministry of Transport, Public Works and 
Water Management (RWS, Rijkswaterstaat) annually measures 
the beach topography by means of Airborne Laser Scanning (ALS). 
The ALS technique has limitations in case of projects that include 
cost effective capturing of 3D data or when dense point cover 
age of the vertical features is required (e.g. steep dune slopes). 
Besides, the ALS data in general can not be provided on de 
mand. First, because flying permissions are needed and secondly 
Figure 1: A real example of a dune erosion on the Dutch coast 
and the possible consequence [GoogleEarth]. 
after-storm weather conditions may hinder or prevent the acquisi 
tion. To summarize, the ALS method offers good results in terms 
of quality and reliability, but is not flexible. One of the poten 
tial alternative techniques is a Land-based Mobile Mapping Sys 
tem (LMMS). LMMS is a complex real-time, multi-tasking and 
multi-sensor system, which integrates (i) a number of line scan 
ners and/or digital cameras for surface mapping, (ii) GNSS for 
positioning and (iii) additional sensors like for example INS to 
monitor the vehicle motion. Those sensors are usually mounted 
on a rigid platform, placed on the roof of a vehicle. The LMMS 
mapping sensors can be of different type and orientation, which 
makes every LMMS system unique in terms of performance and 
thus quality. For an overview of the early LMMS see (Ellum and 
El-Sheimy, 2002). More recent LMMS and system providers are 
described in (Shan and Toth, 2008, Vosselman and Maas, 2010, 
Petrie, 2010). In this research the LMMS, employing a laser scan 
ner as a mapping sensor and integrated GPS/INS system as a main