Three-dimensional surface models of breakwaters, obtained from drone surveys. From the prothotype to the laboratory

Abstract

The recent acquisition of an UAV (Unmanned Aerial Vehicle), or drone, has enriched ongoing LNEC’s Systematic Observation of Maritime Works program (OSOM+) making it possible to use aerial photographic surveys along traditional information obtained in terrestrial visual observation campaigns. Actually, by making use of three-dimensional models of the breakwater provided by the drone, this new information allows a more detailed, qualitative analysis of the condition of the structures, namely a comparative analysis between surveys, regarding eroded volumes and damage progression between campaigns. Also, the same methodology may be adapted to be used in laboratory, for three-dimensional physical scale models of breakwaters, as the ones conducted at LNEC. Also here, the main goal is to obtain envelopes and profiles of the breakwater, allowing the evaluation of the eroded volume and area, of the eroded depth and of the non-dimensional damage parameter. The objective of this paper is therefore to present the capabilities of the surveys obtained by drone both in situ and in laboratory, based on the experience gained outside. To illustrate the methodology, results from the comparison between two surveys of Ericeira's breakwater conducted in 2013 and in 2018, as well as results on the comparison between profiles from a survey conducted on a three-dimensional physical scale model of a breakwater (Leixões) will be shown in this paper.