Timeline visualization of omnidirectional videos

Abstract

There has been an increasing need for timeline visualization of ODV (omnidirectional videos) to help users efficiently navigate to a specific moment or scene in videos. When ODV is viewed, especially when it is being edited, navigation in time is required. There exists massive amount of work over the decades on how to navigate in time in regular video. As the technology has enabled different solutions, traditional solutions like forward and rewind buttons can be replaced with freely draggable timelines. However, omnidirectional video adds some new challenges. Most importantly, in most cases, omnidirectional video is displayed with only one part of the video visible on player viewport. While navigating in time, the user often needs to be aware of what is happening all over in 360-degree domain in the video. This can be made possible in different ways: in addition to normal view, a smaller view called thumbnail displaying the entire video that may be shown, or the view may adjust so that the entire video is visible. In both cases multiple projections can be used. In the latter case, the transition between the normal mode and view mode based on time navigation can depend on projection. Both cases could be done smoothly and possibly in different ways.

A 360-degree video player was developed with two related features: thumbnail attached to timeline and a draggable line on the thumbnail for efficient panning of the main viewport. For evaluation of the system, four different test conditions with four different 360-degree videos were used. Two different shaped thumbnails were used in the evaluation, one is spherical in shape and the other rectangular. Out of the four test conditions the line enabling the panning was included in two cases. According to objective results, the rectangular thumbnail with the panning support is the most efficient one and has the shortest task completion time. According to subjective results, the implemented panning support on both types of thumbnails can be innovative, efficient, easy to use and practical.