## 3 The Joint Technical Activity: Emergency UAS-Based Aerial Photogrammetry
### Main Preliminary Outcomes  
The total mission time from the first take-off to landing of the last mission (including all the battery swaps as well as all unexpected issues) was around 2.5 h for EXE 1 and 3 h for EXE 2, with an effective flight mapping time of about 1 h and 5-10 min (average between all the teams). As reported in Tables 3 and 4, a total of about 4300 and 5200 images (JPEG format) were collected for EXE 1 and EXE 2, respectively. The first approach investigated was to process the images of each team separately (right after their arrival at the CB), using medium/high parameter settings, exportable in low resolution for a fast first delivery. This approach has been tested in order to have the possibility, upon specific request, to export a more accurate product without repeating the elaboration (e.g., the full resolution of the orthophotos has been of 2-4 cm/px for a tiff file dimension of about 3 Gb each).This phase, managed by the CNR mobile unit team, was carried out using the software DJI Terra version 3.9.3. The overall elaboration time was about 1 h and 50 min for EXE1 and 2 h and 20 min for EXE2. In this phase, georeferencing was undertaken by means of the GNSS installed on the UAS (without using GCPs on the field or RTK). The single orthophotos, exported in tiff format with a low resolution of 10 cm/px (maximum size of 135 Mb each), were the first product delivered. All the main products were shared with the UAS CCT through a dedicated folder activated on a web-based file repository of the CNVF. Following other recent field experiences of some of the authors ([32]), a parallel low-resolution elaboration was carried out (always at the CB) using the batch process implemented in Agisoft Metashape version 2.0.3.16915 ([40]), installed in the EUCENTRE workstation. The entire dataset collected was processed in a single chunk with the following workflow: photo alignment (low resolution), depth maps (lowest resolution with aggressive \begin{table}
\begin{tabular}{l c c c} \hline \hline
**ID Team** & **UAS** & **Sub-Area (Figure 3)** & **Dataset Collected** \\ \hline \#1—InGV Roma & DJI Matrice 300 (L1 RGB) & Red & 753 img (6.11 Gb) \\ \hline \#2—CNR & DJI Matrice 300 (L1 RGB) & Yellow & 811 img (6.69 Gb) \\ \hline \#3—ARPA & DJI Matrice 210 V2 (X5s) & Green & 1458 img (10.1 Gb) \\ \hline \#4—CIMA & DJI Matrice 210 V2 (X5s) & Purple & 1203 img (8.11 Gb) \\ \hline \#5—UNIFI & Saturn M2 & Orange & 974 img (8.42 Gb) \\ \hline \multicolumn{3}{c}{} & Tot: \(\
eg\)450 ha (10–15\% overlap) & 5199 img (39.4 Gb) \\ \end{tabular}
\end{table} 
Table 4: EXE 2: summary of the UAS teams involved, target area and dataset collected. \begin{table}
\begin{tabular}{l c c c} \hline \hline
**ID Team** & **UAS** & **Sub-Area (Figure 3)** & **Dataset Collected** \\ \hline \#1—InGV Pisa & DJI Phantom 4 Pro & Red & 755 img (5.25 Gb) \\ \hline \#2—CNR & DJI Phantom 4 Pro V2 & Yellow & 838 img (6.85 Gb) \\ \hline \#3—ARPACAL & DJI Mavic 2 EA & Green & 895 img (14.5 Gb) * \\ \hline \#4—CIMA & DJI Mavic 2 E & Purple & 955 img (7.40 Gb) \\ \hline \#5—ARPA VDA & DJI Phantom 4 Pro & Orange & 874 img (7.10 Gb) \\ \hline \multicolumn{3}{c}{} & Tot: \(\
eg\)450 ha (10–15\% overlap) & 4317 img (41.1 Gb) \\ \end{tabular}
\end{table} 
Table 3: EXE 1: summary of the UAS teams involved, target area and dataset collected. filter), DEM and ortopphoto. The total elaboration time was about 1 h and 30 min both for EXE1 and EXE 2. The orthophoto of the whole area (with a resolution of 10 cm/px) exported in tiff format (with JPEG compression) had a size of about 650 Mb, while the kml file (importable into Google Earth Pro for a fast comparison with the pre-event situation) had a size of approximately 315 Mb. As anticipated, the information that an orthophoto makes available is suitable within an immediate emergency response scenario since it allows for a fast assessment of the general situation, the extension of the affected area and a fast check of the accessibility (Figures 8 and 9).