## 4 Results
### Accuracy Analysis on Natural and Marked Check Points  
For the needs of an independent evaluation of the accuracy of the TLS data orientation process the accuracy analysis was performed on (natural and marked) check points, which were not participating in the data adjustment, and therefore, reliable analysis results could be obtained. Tables 10 and 11 present the statistical values of linear RMSE for two scenarios: (scenario A) close scanner stations where the same fragments of the surface are measured under similar angles and (scenario B) fragments of the surface measured under different angles from different distances and heights of the TLS positions. The accuracy analysis was separately presented for X, Y, and Z components in Table S2. Any marked points were distributed in Test site II and there was no scenario A for Test site IV. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{3}{*}{**Statistics**} & \multirow{3}{*}{**Detector**} & \multicolumn{6}{c}{**The Statistics of the Linear RMSE on Detected Natural Control Points [mm]**} \\ \cline{3-8}  & & & \multicolumn{3}{c}{**Test Site I**} & \multicolumn{3}{c}{**Test Site II**} \\ \cline{3-8}  & & & \multicolumn{3}{c}{**Cartographic transformation**} & \\ \cline{3-8}  & & Spherical & Orthoimage & Mercator & Spherical & Orthoimage & Mercator \\ \hline \multirow{3}{*}{**Avg**} & **FAST** & 3.8 & 3.8 & 3.8 & 1.6 & 3.4 & 3.6 \\  & **SURF** & 4.0 & 3.2 & 3.5 & 1.6 & 3.2 & 3.3 \\ \hline \multirow{3}{*}{**Min**} & **FAST** & 3.7 & 3.5 & 3.5 & 1.0 & 3.2 & 1.4 \\  & **SURF** & 3.7 & 2.1 & 2.4 & 1.3 & 2.8 & 2.9 \\ \hline \multirow{3}{*}{**Max**} & **FAST** & 3.8 & 4.1 & 4.3 & 1.8 & 3.8 & 3.6 \\  & **SURF** & 4.5 & 3.8 & 4.6 & 1.8 & 3.6 & 3.6 \\ \hline \multirow{3}{*}{**Statistics**} & \multirow{3}{*}{**Detector**} & \multicolumn{6}{c}{**Test Site III**} & \multicolumn{6}{c}{**Test Site IV**} \\ \cline{3-8}  & & & \multicolumn{6}{c}{**Cartographic transformation**} \\ \cline{3-8}  & & Spherical & Orthoimage & Mercator & Spherical & Orthoimage & Mercator \\ \hline \multirow{3}{*}{**Avg**} & **FAST** & 5.5 & 5.9 & 6.2 & 34.2 & 23.4 & 9.3 \\  & **SURF** & 6.2 & 6.2 & 6.0 & 9.0 & 5.5 & 43.4 \\ \hline \multirow{3}{*}{**Min**} & **FAST** & 5.2 & 5.8 & 6.0 & 7.2 & 5.8 & - \\  & **SURF** & 6.1 & 6.0 & 6.7 & 7.2 & - & - \\ \hline \multirow{3}{*}{**Max**} & **FAST** & 6.6 & 6.1 & 6.7 & 50.4 & 40.9 & - \\  & **SURF** & 6.7 & 6.4 & 6.4 & 31.9 & - & - \\ \hline \hline \end{tabular}
\end{table} 
Table 9: The statistics of the RMSE values on natural control points for all test sites (both scenarios). When results from Table 10 are analysed, it turns out that better accuracy was obtained for natural check points. This results from the fact that it is the Root Mean Square Error, and the number of natural detected points was considerably higher and this influenced the averaging of results. In scenario B (Table 11) the error values are comparable with results presented in Table 10, this proves the methodological correctness of the TLS data registration process in cartographical projections. Another issue is connected with Test site IV, which was scanned with the lower resolution and worse geometry of scanner stations. This influenced the entire process of data processing and orientation.