## 3 Results
### Radiometric Consistency  
#### 3.2.1 Assessment of the Radiometric Differences between Overlapping Blocks  
For the three processing scenarios, differences were calculated pixel by pixel among corresponding reflectance and VI maps in the overlapping area. While Ig/Ir and Ig/Ir scenarios were independently evaluated, Ig/Ir scenario was compared to the single blocks of Ig/Ir scenario (see Section 2.5). Descriptive statistics for differences calculated on reflectance maps are shown in Table 4, and results of VIs maps are reported in Table 5. Although differences have similar ranges, it is important to remember that reflectance maps have values in the range \([0,1]\), while values for VIs maps are in the range \([-1,1]\). The computed RMSE values are quite close to zero for all cases, but significant differences among single reflectance maps and VI maps can be stressed, considering minimum and maximum absolute values. In particular, differences with maximum and minimum values above 0.4 are calculated for the NIR maps, differences reach values close to 0.3 for the red-edge map, and lower values are registered for the green and red maps, with minimum and maximum absolute values below 0.2 for the red maps in some cases. A similar behavior is also evident for the VI maps, where the differences calculated on NDVI maps assume lower RMSE values, while maximum and minimum values even greater than 0.5 are calculated for many VIs. The comparison between the statistics computed for Ig/Ir and Ig/Ir scenarios shows that both reflectance and VI map differences reach very similar values. Figure 6: The cloud 3D distance maps between areas 3 and 4, expressed in meters: (**a**) direct georeferencing (DG); (**b**) independent georeferentiation/independent radiometric processing (Ig/Ir); (**c**) joint georeferentiation/independent radiometric processing (Ig/Ir). To assess the significance of the calculated values, the differences are presented in the form of box and whisker plots. Figure 7 reports box and whisker plots for differences computed on reflectance maps, while in Figure 8 VI results are shown. The plots do not refer to the Jg/Ir scenario, as similar results are obtained with respect to Ig/Ir scenario. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & & **Green** & **Red** & **Red-Edge** & **NIR** \\ \hline  & Min. & \(-0.1923\) & \(-0.1640\) & \(-0.2957\) & \(-0.5217\) \\  & Max. & \(0.2822\) & \(0.2194\) & \(0.4168\) & \(0.5931\) \\
3 Ig/Ir–4 Ig/Ir & Mean & \(0.0088\) & \(-0.0013\) & \(0.0268\) & \(0.0368\) \\  & STD & \(0.0572\) & \(0.0272\) & \(0.0367\) & \(0.1103\) \\  & RMSE & \(0.0579\) & \(0.0272\) & \(0.0454\) & \(0.1163\) \\ \hline  & Min. & \(-0.0947\) & \(-0.1042\) & \(-0.2336\) & \(-0.3432\) \\  & Max. & \(0.2538\) & \(0.1763\) & \(0.3557\) & \(0.6642\) \\
3 Ig/Ir–Ig/Ir & Mean & \(0.0166\) & \(0.0061\) & \(0.0182\) & \(0.0482\) \\  & STD & \(0.0305\) & \(0.0131\) & \(0.0208\) & \(0.0692\) \\  & RMSE & \(0.0348\) & \(0.0144\) & \(0.0276\) & \(0.0843\) \\ \hline  & Min. & \(-0.1791\) & \(-0.1964\) & \(-0.3547\) & \(-0.3863\) \\  & Max. & \(0.1915\) & \(0.1696\) & \(0.2769\) & \(0.5047\) \\
4 Ig/Ir–Ig/Ir & Mean & \(0.0079\) & \(0.0075\) & \(-0.0086\) & \(0.0115\) \\  & STD & \(0.0338\) & \(0.0195\) & \(0.0213\) & \(0.0613\) \\  & RMSE & \(0.0347\) & \(0.0208\) & \(0.0230\) & \(0.0624\) \\ \hline  & Min. & \(-0.1826\) & \(-0.1761\) & \(-0.3217\) & \(-0.5519\) \\  & Max. & \(0.2670\) & \(0.1874\) & \(0.4511\) & \(0.5831\) \\
3 Ig/Ir–4 Jg/Ir & Mean & \(0.0087\) & \(-0.0014\) & \(0.0270\) & \(0.0365\) \\  & STD & \(0.0572\) & \(0.0276\) & \(0.0446\) & \(0.1104\) \\  & RMSE & \(0.0579\) & \(0.0277\) & \(0.0522\) & \(0.1163\) \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Summary statistics of the differences between reflectance maps in the overlapping area. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & & **NDVI** & **GNDVI** & **NDRE** & **NDVIre** & **NGRDI** \\ \hline  & Min. & \(-0.4431\) & \(-0.3859\) & \(-0.2651\) & \(-0.5629\) & \(-0.4726\) \\  & Max.