Towards evaluation of immersion, visual comfort and exploration behaviour for non-stereoscopic and stereoscopic 360° videos.

Immersion, visual comfort, and exploration behaviour are important aspects that affect the overall quality of experience for 360° videos. To analyze the benefits of stereoscopic and non-stereoscopic 360° videos in terms of these factors, we created a dataset and conducted a subjective study. The dataset consists of five different high-resolution $8 \mathrm{~K}$ omnidirectional videos as stereoscopic and non-stereoscopic variants. The videos have been recorded using a Kandao Obsidian Pro camera. For the comparison, we designed and performed a subjective test with 30 participants. Here, each subject watched both HEVC (libx265) encoded versions of the source video and rated the videos viewed regarding presence, visual comfort, and quality. The results indicate that with the test protocol followed, non-stereoscopic video viewing leads to slightly better presence, visual comfort, and quality ratings compared to the stereoscopic variants. Further, the stereoscopic 360° videos may suffer from visual artefacts potentially leading to lower video quality and further lower quality of experience results. The exploration behaviour was found to be very similar for both non-stereoscopic and stereoscopic video viewing. Overall, it can be concluded that there is a slight tendency for non-stereoscopic video viewing to be preferred over stereoscopic video viewing. The dataset is made publicly available with the paper and includes both variants of all source videos along with the subjective data, and behaviour data, following an open-science approach.