Fusion of TLS and Uav Photogrammetry Data for Post-Earthquake 3d Modeling of a Cultural Heritage Church

Abstract

<p><strong>Abstract.</strong> Nowadays, the necessity of heritage documentation is essential for monitoring, maintenance, and understanding needed for conservation. The survey phase has been considerably improved using cutting-edge technologies such as Unmanned Aerial Vehicles (UAV) and Terrestrial Laser Scanners (TLS). Both of these technologies have been applied in heritage documentation individually or combined. Heritage documentation in a post-natural disaster is a situation that requires rapid data acquisition on a hazardous field. On 12th of June 2017 an earthquake (Mw = 6.3), south of Lesvos island, Greece occurred, which was devastating for the Vrisa village destroying, among many other buildings the main church. The Greek State decided from the first moment to restore the whole village, which was proclaimed as a “traditional settlement” since 2002, in its original place starting from the church and the school due to the symbolic meaning that those have to a local community. For this purpose, a 3D model of the church was requested by the authorities for damage assessment. In this paper TLS and UAV photogrammetry has been used in an integrated design to rapidly facilitate the acquisition of the whole church, eliminating all possible occlusions. The TLS was exploited for the acquisition of the facades while the UAV was used for the acquisition of the roof. The recent improvement of the post-processing algorithms provided the ability to implement the fusion of TLS and UAV models and deliver an accurate 3D model of the whole church the same day that the survey was conducted.</p>

Multiplatform-SfM and TLS Data Fusion for Monitoring Agricultural Terraces in Complex Topographic and Landcover Conditions

“…The choice to start the ICP process from the overlapping stable areas and then extend the coregistration process to the whole area certainly improved the quality of the alignment, as demonstrated in several studies [71,91]. Other previous studies [35][36][37]39,90] in which the ICP method was used to coregister TLS and SfM data showed good results.…”

“…We integrated raw point clouds of TLS and unmanned aerial vehicle (UAV)/terrestrial SfM to exploit the intrinsic advantages and overcome the weaknesses of each dataset. A data fusion approach, namely SfM-TLS merge, has been applied in cultural heritage environment and archaeological research [19,[32][33][34][35][36] and in environmental monitoring [14,30,[37][38][39]. This suggests that SfM-TLS fusion achieves better performance in various applications compared to the use of a single data type [40].…”

Assessment of Earthquake-Induced Damage Level on Buildings: Analysis of Two Different Survey Methods for a Case Study

“…The extraction and processing of data acquired via UAV allows to obtain, through the application of photogrammetric techniques and through the use of algorithms derived from Structure from Motion (SfM) studies, reliable 3D study models of the affected sites, on the basis of a photographic sequence. Many researches have shown the effectiveness of validating the use of drones in emergency phases, in particular after seismic events: De Oliveira Silva et al (2019) propose a procedure to support the design of aid distribution networks in disaster response operations using UAVs and geographic information systems (GIS), referring to the post-disaster area of Duque de Caxias, in the state of Rio de Janeiro, Brazil; Chatzistamatis et al (2018) underline the importance of combining UAV survey with Terrestrial Laser-Scanning acquisitions for the detection of buildings after the 2017 earthquake in the South of Lesvos island, Greece; Dominici et al (2016) test the use of drones to the analyses of post-catastrophe scenarios after the seismic event occurred in L'Aquila (Italy), 2009, and they underline, referring to several case studies, the advantages of UAV photogrammetry in terms of: -Safety issues: absence of risk for inspectors; -Possibility to inspect areas with difficult accessibility; -High resolution photograms; -Rapidity in survey and elaboration phases; -Repeatability of test and low cost of survey instruments. With the aim to employ all different acquisition systems developed in the field of operative survey for the support of damage monitoring and risk management activities in hazardous situations, the Copernicus EMS was developed, starting from year 2012, in the framework of the European Earth-observation program called Copernicus.…”

Post-Earthquake 3d Building Model (Lod2) Generation From Uas Imagery: The Case of Vrisa Traditional Settlement, Lesvos, Greece

“…As Letellier et al (2007) compiled, the post-earthquake recording of cultural heritage buildings is significant. After an earthquake, the damage assessment of the buildings is still made through fieldwork, however, these traditional methods are timeconsuming, and sometimes dangerous due to the extensive damages (Chatzistamatis et al, 2018).…”