# 3D User Interface Design and Usability for Immersive VR
## 5 Results and Data Analysis
### Observation and Interview Results  
The results of different observations collected during the testing session with analysis of the video recordings are presented in this section. The observations include the number of eye gazes, the footstep movements, and the errors. In addition, the interview results which include the user feedback for each interaction and for the overall experience of performing the desktop tasks in the immersive VR environment using the 3D UI design are also presented. **Number of Eye Gazes:** all the video recordings for the 21 participants were analyzed, specifically the video of initial interface for each participant under the standing experience only. The number of eye gazes were calculated for a specific task, which was task 2 (open a specific folder) in the test case scenario. Ideally, the user needs two gazes only to perform the open task using the 3D UI, one gaze at the lower (interaction) layer to choose the intended file, and the second gaze to look at the upper (screen) layer to view the opened file. The number of eye gazes for each participant for that specific task were calculated manually. It was found that all users were able to perform the task using two gazes only. This shows a good indication that the participants were able to understand the 3D UI design and interact with it effectively. **Number of Footsteps:** the users' footstep movements during the testing session by observing the movement outside the defined boundary mentioned in Section 3 were analyzed. Additionally, for certain cases, the video recordings were watched for further confirmation. It is to be noted that the interface does not rely on any type of lower body motion, e.g., walking. The purpose of tracking footsteps is to find if there is any design flaw associated with the interface that results in user making physical movements that are not required. The analysis did not find any significant effect of the footstep movements on the UI or interaction modes. None of the participants went outside the defined boundary, rather a slight movement in terms of rotation was noticed since the 3D UI allows to interact with multiple screens portrayed within a curved 360-degree effective field of view available for the user. It was concluded that there is no significant relationship between the physical movement and the interactions modes. **Error Analysis:** during the testing sessions, the observer observed and wrote the comments for any errors that might occur in each UI. The observation did not find any significant errors in any UI Rather, some participants forget how to perform certain tasks. For example, in the point-and-click UI, one participant forgot how to perform the close task. This suggests that the need to enhance the visibility of the close button, either in terms of size, color, or label. It is intended to be explored in future work. While in the controller-based DM UI, one participant forgot how to perform the close task using the controller twice in standing and seated positions. Another one forgot how to perform the scroll task. An additional participant forgot to switch the controllers; the user was trying to display the menu using the right controller. The reason might be that the training given to the users was short. This will be explored in the future work. \begin{table}
\begin{tabular}{c c c c} \hline \hline  & \multicolumn{3}{c}{**Source of Variation**} \\ \hline  & **Columns (Factor 1)** & **Sample (Factor 2)** & **Interaction** \\ \hline SS & 13,112.714 & 408.960 & 28.396 \\ df & 2 & 1 & 1 \\ MS & 6556.357 & 408.960 & 14.198 \\ F & 14.613 & 0.911 & 0.031 \\ \(p\)-value & \(2.09\times 10^{-6}\) & 0.341 & 0.968 \\ Fcrit & 3.071 & 3.920 & 3.071 \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Two-way variance—ANOVA. Interview Results: the participants were interviewed after each UI test under each condition of the experience. The interview was guided by a script consisting of one closed question.