A review of the use of terrestrial laser scanning application for change detection and deformation monitoring of structures

Change detection and deformation monitoring is an active area of research within the field of engineering surveying as well as overlapping areas such as structural and civil engineering. The application of Terrestrial Laser Scanning (TLS) techniques for change detection and deformation monitoring of concrete structures has increased over the years as illustrated in the past studies. This paper presents a review of literature on TLS application in the monitoring of structures and discusses registration and georeferencing of TLS point cloud data as a critical issue in the process chain of accurate deformation analysis. Past TLS research work has shown some trends in addressing issues such as accurate registration and georeferencing of the scans and the need of a stable reference frame, TLS error modelling and reduction, point cloud processing techniques for deformation analysis, scanner calibration issues and assessing the potential of TLS in detecting sub-centimetre and millimetre deformations. However, several issues are still open to investigation as far as TLS is concerned in change detection and deformation monitoring studies such as rigorous and efficient workflow methodology of point cloud processing for change detection and deformation analysis, incorporation of measurement geometry in deformation measurements of high-rise structures, design of data acquisition and quality assessment for precise measurements and modelling the environmental effects on the performance of laser scanning. Even though some studies have attempted to address these issues, some gaps exist as information is still limited. Some methods reviewed in the case studies have been applied in landslide monitoring and they seem promising to be applied in engineering surveying to monitor structures. Hence the proposal of a three-stage process model for deformation analysis is presented. Furthermore, with technological advancements new TLS instruments with better accuracy are being developed necessitating more research for precise measurements in the monitoring of structures

Synergistic Exploitation of Geoinformation Methods for Post-earthquake 3D Mapping and Damage Assessment

This paper presents a methodological framework, which establishes links among the: i. 3D mapping, ii. 3D model creation and iii. damage classification grades of masonry buildings by European Macroseismic Scale-98 and the application of geoinformation methods towards 3D mapping and damage assessment after a catastrophic earthquake event. We explore the synergistic exploitation of a Real Time Kinematics system, terrestrial photogrammetry, Unmanned Aircraft Systems and terrestrial laser scanner for collecting accurate and high-resolution geospatial information. The proposed workflow was applied at the catastrophic earthquake of June 12th, 2017 on the traditional settlement of Vrisa on the island of Lesvos, Greece. The Structure from Motion method has been applied on the high-resolution terrestrial and aerial photographs, for producing accurate and very detailed 3D point clouds of the damaged buildings of the Vrisa settlement. Additionally, two Orthophoto maps and two Digital Surface Models have been created, with a spatial resolution of 5 cm and 3 cm, respectively. The first orthophoto map has been created just one day after the earthquake, while the second one, a month later. The significant advantages of the proposed methodology are: (a) the production of reliable and accurate 2D and 3D information at both village and building scales, (b) the ability to support scientists during building damage assessment phase and (c) the proposed damage documentation provides all the appropriate information which can augment all experts and stakeholders, national and local organizations focusing on the post-earthquake management and reconstruction processes of the Vrisa traditional village