## 4 Results and Discussion
### Navigation Using Aruco Markers  
After selecting Aruco markers for our system, the authors built maps for the first and the fourth floor. Depending on which floor the PVI wish to navigate, the right map is loaded from the database once the application has been launched. At that point, the prototype is controlled by the user via voice commands. Figure 11 showed screenshots of the system. As shown in part (a) of the Figure 11, it asks the PVI to select the starting point by pressing on the screen. As shown in part (b), it launches the mobile camera and guides them to search for any markers to be used as a starting point. As shown in part (c), the third step is to select the destination using voice commands. For example, PVI say \"lab 417\" to be their destination. The system calculates the shortest path from the starting point to the destination using the Dijkstra algorithm. Then, it launches the smartphone camera and starts guiding the PVI to the next point using voice commands as shown in part (d). The authors used the commands shown in Table 1.  
Figure 10: Evolution of quick response (QR)codes and Aruco markers: (**a**) Results of evaluating Aruco markers in different situations from various distances (1, 2, 3, and 4 m); (**b**) results of evaluating QR codes in different situations from various distances (1, 2, 3, and 4 m). _Appl. Sci._**2019**, \(9\), 5110 \begin{table}
\begin{tabular}{c c c} \hline \hline
**Command Type** & **Name** & **Description** \\ \hline \multirow{4}{*}{[PERSON]’s voice commands} & “Go to” + destination & The PVI order the prototype to lead them toward the predefined destinations. \\  & “Start” & The PVI order the prototype to go to the start activity to select the start point. \\  & “Exit” & The PVI order the prototype to exit. \\  & “Incorrect destination, you should press on the screen and select it again” & The prototype informs the user that they should provide another destination. \\  & “Go straight” + number of steps & The prototype directs the user to go straight for number of steps. \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Commands given by the PVI and navigation commands by the prototype. Figure 11: Screenshots of our prototype: (**a**) User presses this button to select the starting point; (**b**) User moves the smartphone’s camera left and right to detect the starting point; (**c**) User presses this button to select the destination point; (**d**) User selects the destination using voice commands to start navigation; (**e**) User moves the smartphone camera left and right to detect the next point until reaching destination. For example, PVI select the elevator as a starting point which is stored in the database as a node 1. They also choose their destination as \"lab 417\" which is stored as node 5. Using our system, the shortest path between node 1 and node 5 is calculated as shown in Figure 12. To reach laboratory number 417 (node 5), PVI start walking from the elevator (node 1). They go from node 1 to the next node, which is node 7. At node 7, navigation commands guide them to turn left and move straight for ten steps to reach node 6. Finally, PVI walk for twenty steps to reach node 5, which is the destination. The authors divided testing of the prototype into two test cases. The first case was to test it with blindfolded people or PVI, collection of the feedback and updating it. The second case is to evaluate the prototype again after applying modifications using the PVI's comments. The prototype was tested on the corridor of the first and the fourth floor (Video S1, Video S2). In the beginning, a short introduction to the case study was provided to the participants. The authors trained the users for 30 min to know how to use the prototype for navigating from one place to another. The goal was to test whether the prototype was easy to use or not. It also tested if the users could effectively interpret the feedbacks or not. The authors made sure that there were no obstacles on the way to the destination.