Kinematic GPS survey as validation of LIDAR strips accuracy

M. Barbarella, C. Gordini

Abstract


As a result of the catastrophic hydrogeological events which occurred in May 1998 in Campania, in the south
of Italy, the distinctive features of airborne laser scanning mounted on a helicopter were used to survey the
landslides at Sarno and Quindici. In order to survey the entire zone of interest, approximately 21 km2, it was
necessary to scan 12 laser strips. Many problems arose during the survey: difficulties in receiving the GPS
signal, complex terrain features and unfavorable atmospheric conditions. These problems were investigated
and it emerged that one of the most influential factors is the quality of GPS signals. By analysing the original
GPS data, the traces obtained by fixing phase ambiguity with an On The Fly (OTF) algorithm were isolated
from those with smoothed differential GPS solution (DGPS). Processing and analysis of laser data
showed that not all the overlapping laser strips were congruent with each other. Since an external survey to
verify the laser data accuracy was necessary, it was decided to utilize the kinematic GPS technique. The laser
strips were subsequently adjusted, using the kinematic GPS data as reference points. Bearing in mind that in
mountainous areas like the one studied here it is not possible to obtain nominal precision and accuracy, a
good result was nevertheless obtained with a Digital Terrain Model (DTM) of all the zones of interest.

Keywords


LIDAR;GPS;DTM;landslide body;Sarno

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References


DOI: https://doi.org/10.4401/ag-3145
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Published by INGV, Istituto Nazionale di Geofisica e Vulcanologia - ISSN: 2037-416X