Innovative Methodologies for Structural Control of Masonry Building under Preservation or Reconstruction Using Geomatic and Topographic Techniques

Operating a deformation analysis on masonry and ancient monumental buildings is not a simple operation. This type of extremely complicated structures present great irregularities and a variety of construction techniques that not always are visible. Thus, the measurement's network has to be wisely projected in order both to reveal all possible kinematic mechanisms, displacements, eventual deformations and to guarantee an elevated reliability of the whole surveying network. For this reason a preliminary deformation analysis is crucial to identify representative points on the structure that will manifest its dynamic characteristics. In our case, an L-shaped monumental masonry building, seriously damaged by the earthquake that hit L'Aquila almost three years ago was chosen to curry out this experiment. The survey methodology was indeed based on the use of 30 mini-reflectors installed on the building's facades and observed by a robotic fully-motorized total station Leica TS30. Extra mini prisms that are also installed on stable surrounding structures are used to orientate the instrument before any set of measurements. All the stable points and especially the base where the total station is positioned for each survey are periodically monitored by a GNSS triangulation in order to guarantee their stability over time. After an immediate estimation of all coordinates made automatically by the instrument a detailed statistical adjustment of the whole network is performed to enhance both the network's reliability and accuracy. With periodic repeatability of all measurements the final position of each point is calculated, adjusted and integrated to the final database. In this way a complete knowledge for the structure's dynamics also considering the seasonal changes is gathered in order to evaluate possible final deformations of the whole structure

Historic cartography of L'Aquila city as a support to the study of earthquake damaged buildings

The city-center of L'Aquila suffered big damages from the main seismic event (6th April 2009, 3:32 a.m., local time; Ml=5.8, Mw= 6.2) of the seismic sequence that included hundreds of aftershocks (more than 30 of them 3.5<5.0) (INGV, 2009). Causes and modality of the collapse of some buildings are still under investigation. A 1:2000 map representing the center of L'Aquila city at the beginning of twentieth century was recently found and the comparison of this map with contemporary ones can help the study of the causes of the different response to seismic stress to different aged buildings. This study represents the first step to build a database of historic buildings in L'Aquila to test a potential correlation between the anti-earthquake regulations adopted over the years and the resulting damages. A comparison with post earthquakes damage map and the map of seismic zoning was performer to find all the possible combination of other parameters that together with building age can help to evaluate building vulnerability

UAV APPLICATION IN POST - SEISMIC ENVIRONMENT

Abstract. On April 6, 2009, an earthquake of 6.3 magnitude struck central Italy with its epicentre near L'Aquila, at 42.3502° N, 13.3762° E. The earthquake damaged 3000 to 11 000 buildings in the medieval city of L'Aquila. Several buildings totally collapsed, 308 people were killed. The post emergency phase till now is just at its beginning step. Conventional surveying techniques using high precision total stations, GNSS receivers and laser scanners for investigations on damaged buildings are always becoming more automated, accurate and operative and even much more fast. Even if these techniques represent instruments of extreme operability there are still many evident limits on their use, especially regarding the survey of both the roofs and the facades of tall buildings or dangerous places, typical on post earthquake situations. So using micro UAVs for surveying in such particular cases, many of these problems can be easily bypassed. In fact, the present work aims on experimenting using multi-rotor micro UAVs, that will allow high quality image capturing on roofs and facades of structures in the old city center of L'Aquila. To obtain actual stereoscopic acquisitions of buildings some conditions on the geometry of acquisition have to be observed, for this reason, taking as a guideline classic flight photogrammetric, a flight planning software was developed. Accurate planning for UAVs acquisitions is very important also considering the reduced autonomy of such vehicles. This can be a strategic point if we want to use UAVs for early damage assessment and also for post event reconstruction planning

UAV photogrammetry in the post-earthquake scenario: case studies in L'Aquila

The main advantage of using the Unmanned Aerial Vehicle (UAV) photogrammetry in a post-earthquake scenario is the ability to completely document the state of the structures and infrastructures, damaged by the earthquake, ensuring the safety of all operators during the data acquisition activities. The safety and accessibility aspect in the area is of crucial concern after an earthquake and sometimes many areas may be inaccessible, but, at the same time, it is necessary to collect data in order to monitor and evaluate the damage. The development of new algorithms in the field of Computer Vision drastically improved the degree of automation of the 3D point clouds generation using the photogrammetry techniques. In addition, data acquisition techniques using the UAV allow a complete 3D model with the highest possible resolution especially with respect to the conventional satellite or aerial photogrammetry to be produced. These advantages make the UAV photogrammetry highly suitable for surveys in a geo-hazard context as in a post-earthquake scenario. Some results from surveys carried out with the UAV photogrammetry after L'Aquila Earthquake occurred in 2009 will be presented and discussed

The survey of the Basilica di Collemaggio in L’Aquila with a system of terrestrial imaging and most proven techniques

The proposed job concerns the evaluation of a series of surveys carried out in the context of a campaign of studies begun in 2015 with the objective of comparing the accuracies obtainable with the systems of terrestrial imaging, compared to unmanned aerial vehicle imaging and laser scanner survey. In particular, the authors want to test the applicability of a system of imaging rover (IR), an innovative terrestrial imaging system, that consists of a multi-camera with integrated global positioning system (GPS)/global navigation satellite system (GNSS) receiver, that is very recently released technique, and only a few literature references exist on the specific subject. In detail, the IR consists of a total of 12 calibrated cameras – seven “panorama” and five downward-looking – providing complete site documentation that can potentially be used to make photogrammetric measurements. The data acquired in this experimentation were then elaborated with various software packages in order to obtain point clouds and a three-dimensional model in different cases, and a comparison of the various results obtained was carried out. Following, the case study of the Basilica di Santa Maria di Collemaggio in L’Aquila is reported; Collemaggio is an UNESCO world heritage site; it was damaged during the seismic event of 2009, and its restoration is still in progress

Development of a software to plan UAVs stereoscopic flight: An application on post earthquake scenario in L'Aquila city

On April 6, 2009, an earthquake hit the historic center of L'Aquila city, hundreds of victims, thousands of collapses. During the post-emergency a continuous monitoring of all building is crucial in order to guarantee that each structure at least will not worsen its stability until the final reconstruction is completed. So detailed surveying of all building is performed using different geomatic techniques as total stations, land photogrammetry, and laser scanners. Even if all these techniques can perfectly respond to many crucial post hazard needs, there are still many monitoring that cannot be completely carried on with traditional techniques. For these reasons, in this work, the advantages of using multirotor UAVs will be illustrated; UAVs can be fully remote controlled and so the geometry of photogrammetric image acquisition can be imposed. For this task planning of flight is essential so a package was realized to obtain actual photogrammetric stereoscopic acquisitions. © 2013 Springer-Verlag Berlin Heidelberg

development of a software to optimize and plan the acquisitions from uav and a first application in a post seismic environment

AbstractAn Unmanned Aerial Vehicle (UAV) is an aircraft without a human pilot on board. UAVs allow close-range photogrammetric acquisitions potentially useful for building large-scale cartography and acquisitions of building geometry. This is particularly useful in emergency situations where major accessibility problems limit the possibility of using conventional surveys. Presently, however, flights of this class of UAV are planned based only on the pilot's experience and they often acquire three or more times the number of images needed. This is clearly a time-consuming and autonomy-reducing procedure, which is certainly detrimental when extensive surveys are needed. For this reason new software, to plan the UAV's survey will be illustrated

Automatic three-dimensional features extraction: The case study of L'Aquila for collapse identification after April 06, 2009 earthquake

This paper illustrates an innovative methodology for post-earthquake collapsed building recognition, based on satellite-image classification methodologies and height variation information. Together, the techniques create a robust classification that seems to yield good results in this application field. In the first part of this study, two different feature extraction methodologies were compared, based respectively on pixel-based and object-oriented approaches. Then the classification results of the most accurate classification methodology, obtained on an eight band WorldView-2 monoscopic image, were completed with height variation information before and after the event. The height difference is calculated, comparing a photogrammetric DSM, obtained using a photogrammetric rigorous orbital model on some EROS-B 0.7 metre across-track stereopairs with a 'roof model' before the earthquake

Shoreline extraction based on an active connection matrix (ACM) image enhancement strategy

Coastal environments are facing constant changes over time due to their dynamic nature and geological, geomorphological, hydrodynamic, biological, climatic and anthropogenic factors. For these reasons, the monitoring of these areas is crucial for the safeguarding of the cultural heritage and the populations living there. The focus of this paper is shoreline extraction by means of an experimental algorithm, called J-Net Dynamic (Semeion Research Center of Sciences of Communication, Rome, Italy). It was tested on two types of image: a very high resolution (VHR) multispectral image (WorldView-2) and a high resolution (HR) radar synthetic aperture radar (SAR) image (Sentinel-1). The extracted shorelines were compared with those manually digitized for both images independently. The results obtained with the J-Net Dynamic algorithm were also compared with common algorithms, widely used in the literature, including theWorldView water index and the Canny edge detector. The results show that the experimental algorithm is more effective than the others, as it improves shoreline extraction accuracy both in the optical and SAR images

an application of cosmo sky med to coastal erosion studies

AbstractStarted in 2009, the COSMOCoast project aims to the investigation of the potential of Remote Sensing in support to the management of coastal areas. Particular attention is paid to the contribution of data acquired from the COSMO-SkyMed constellation, in view of their frequency of acquisitions and ground resolution; in particular this paper aims at assessing the potential of COSMO-SkyMed data for coastline delineation. The results are conceived to be of particular interest for public administration bodies in charge of coastal defense. Keywords: Remote Sensing, Coastal Zones Management, COSMO-SkyMed