# Subtitling 3D VR Content with Limited 6 DoF: Presentation Modes and Guiding Methods
## 4 Results: User Tests
### Results
#### 4.3.1. Test Condition: Presentation Modes
With regard to the results from the ad hoc questionnaire on preferences, the answers are presented in the bar charts in Figure 5. In terms of avoiding content blocking/obstruction, the most preferred mode was _Always-visible_ subtitles, closely followed by the other two options. In terms of ease of reading, _Always-visible_ subtitles were also the most preferred mode, followed by _Fixed-Positioned_ subtitles. The reason why _Comic-style_ was the third preference may be due to the fact that subtitles in such a presentation mode were somewhat small, and thus not easy to read, when the distance between the user and the speaker was large. In terms of reading comfort, _Fixed-Positioned_ subtitles were the third preference. This may be because the users had to change their viewing patters to read the subtitles and see the speakers when using this mode. In terms of speaker's identification, _Comic-style_ was the most preferred option, because subtitles were associated with the target speaker when using this mode, and _Always-visible_ subtitles were the second preferred option. As expected, _Fixed-Positioned_ subtitles scored worst with regard to this aspect. In terms of integration with the VR content, _Comic-style_ subtitles were again the preferred mode, because subtitles were deliberately integrated with the associated speaker(s). No significant differences were obtained between the other two modes with regard to this aspect. In terms of the impact of distance and viewing perspective, the _Always-visible_ subtitles mode was clearly preferred, because these two factors had a significant impact on the other two modes. These other two modes may have been adjusted such that the subtitles' rendering planes were always normal/orthogonal to the user's viewing perspective, and their size was dynamically adapted according to the distance; however, this needs \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Presentation** & **Mean** & **Standard** & **Compared to** & **Compared to** & **Compared to** \\
**Mode** & **Mean** & **Deviation** & **Always-Visible** & **Fixed-Positioned** & **Comic-Style** \\ \hline Always-visible & 3.635 & 1.37 & **-** & **\(p\)-value = 0.04249** & **\(p\)-value = 0.03** \\ Fixed-positioned & 3.541 & 1.321 & **\(p\)-value = 0.04249** & - & \(p\)-value = 0.1187 \\ Comic-style & 3.448 & 1.329 & **\(p\)-value = 0.03** & \(p\)-value = 0.1187 & - \\ \hline \hline \end{tabular}
\end{table} 
Table 6: IPQ—Experienced Realism Scale. Figure 4: Boxplots of IPQ scales for each VR subtitling presentation mode (AV = _Always-Visible—Mode A_; FP = _Fixed-Positioned—Mode B_; CS = _Comic-Style—Mode C_). further investigation and fine-tuning. Finally, in overall terms, _Always-visible_ subtitles was the most preferred mode, closely followed by _Comic-style_ subtitles. This is in line with the results from the IPQ questionnaire, and confirms that the two innovative 3D VR subtitling presentation modes proposed in this study provide benefits in terms of the user experience. Finally, the user's position and camera position (i.e., the viewpoints) were recorded each 0.5 s during all test conditions. The goal of this was to compare the users' viewing patterns for each of the considered subtitling presentation modes to assess whether these modes have any impact on the omnidirectional 3D scene exploration. The obtained results for a sub-sample of eight users (those who watched each presentation mode for Clip 1, Table 1) are shown in Figure 6. These results confirm that, when using the _Always-visible_ mode, the users further explored the omnidirectional 3D environment, because the subtitles  
Figure 5: Preferences for 3D VR subtitling presentation modes. were never overlooked.