## 3 Aerial Survey by UAS
### Mission Planning
According to the project, several types of flight plans can be realized: polygon, grid, double grid, circular, and free flight. Polygon and grid flight plans are particularly suitable for surveying generally 2D objects, while double grid and circular plans are used for surveying 3D objects. An example of the flight plan is performed by the use of Pix4D software on the archaeological area of luvanum, which is a site from Roman times and is located in the countryside of Montenerodomo (41\({}^{\circ}\)59\({}^{\circ}\)54.26\({}^{\prime\prime}\) N-14\({}^{\circ}\)14\({}^{\prime}\)59.60\({}^{\prime\prime}\) E), Chieti (Italy), and concerns an area of approximately 4 hectares. The advantage of using flight planning software, such as Pix4D, is that it displays the high-resolution geometric orthophoto of the site of interest and the digital terrain model on the display of one's device (smartphone, tablet, etc. ); in this way, the spatial coordinates of the waypoints can be determined automatically and quickly. Table 5 shows schematically the different flight types applied over the same archaeological area. The same settings were used for the different flight types; in particular, an overlap and sidelap value of 80% and a flight altitude of 80 metres were set in the planning step of the aerial flight mission. In addition, the flight plans were carried out in order to obtain a GSD of approximately 2 cm for nadiral acquisition and roughly 4 cm for oblique acquisition (circular mode). Before starting the flight mission, a good GNSS satellite configuration and suitable weather conditions must be checked [63]. In order to check suitable weather conditions to perform photogrammetric flight, several websites and apps are available, such as the uavforecast.com service. However, before executing the flight, in addition to checking the weather and GNSS conditions, it is necessary to verify that the airspace where the photogrammetric mission is to be carried out is free of any restrictions or prohibitions, as described in more detail in the following paragraph (Section 3.3). Once the good weather and GNSS conditions and regular procedures (air rules) are verified, the flight plan can be carried out by UAS. Flight planning operations are organised and controlled by the ground control station (GCS); the GCS manages the launch, landing, flight, and eventual recovery, and handles any emergency situations. Furthermore, the GCS (installed on a dedicated remote controller or implemented on laptop devices, smartphones and tablets) operates as an interface between the UAS system and the outside world, managing communication with the various sensors [64]. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Software** & **Manufacturer** & **Ref.** \\ \hline PIX4 Dcapture & Pix4D, Switzerland & [58] \\ UgCS UAV Mission Planning Software & Geometrics, U.S.A. & [59] \\ UAV Flight Map Pro Planner & Drone Emotions srl, Italy & [60] \\ DJI GS PRO & SZ DJI Technology Co. Ltd., China & [61] \\ Mission Planner & Created by [PERSON] for the ArduPilot & [59] \\ eMotion, flight planning software for eBee drones & Aggale Aerial Systems Inc., U.S.A. & [62] \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Software for flight and mission planning. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Location** & **Type** & **Flight Plan** \\ \hline \hline  
\end{tabular}
\end{table} 
Table 5: Type of flight plans.