MICRO UAV FOR POST SEISMIC HAZARDS SURVEYING IN OLD CITY CENTER OF L'AQUILA

Almost three years ago a disastrous earthquake hits the old city of L'Aquila, hundreds of victims, thousands of collapses. The post emergency and very crucial phase regarding surveys, structure controls and investigations till now is fully underway. Conventional surveying techniques using high precision total stations, GNSS and laser scanners for investigations on damaged buildings are always becoming more automated, accurate and operative in always shorter time manners. 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. For example, the details of a bell set at 40 m height are always hidden for most of the instruments such as laser scanners or total stations, certainly, the non optimal capturing angle and the bad visual would represent considerable limits for the identification of potential damages. The present work aims on experimenting an innovative surveying methodology using multirotor UAVs (Unmanned Aerial Vehicles), fully remote controlled, that will allow high quality image capturing on roofs and facades of structures in the old city center of L'Aquila. These data will be elaborated with photogrammetric software suits to create digital models of the building and databases with its detailed characteristics. The field of application can be the concept of photogrammetry of proximity as the flights are carried out at altitudes much lower than an aerial photogrammetry, moreover, as the flight is operated in a fully automated way, extended areas can be surveyed in a fat and economic way. This paper highlights the reasons that led to explore the use of a Micro UAV in the relief of an old city center through a real case application. Each step of photogrammetry is described, from the planning software of the flight plan and gripping points to ensure the coverage required to the execution of the flight and the data processing. The experiments were performed using an IPT Mikrokopter (Rome - Italy), in octo-configuration (8 engines) in order to have better flight stability and raise the needed payload for an SLR digital camera; the flight was also performed in fully automatic way at the height of 80m. The results presented in this study highlight the excellent integration of these surveys with those made by conventional instruments and propose this methodology as an effective documentation necessary for a recovery of an old city in a post natural disaster.