360° video and Virtual Reality are powerful techniques for giving viewers a sense of ‘Being There’ , and are becoming increasingly popular. However, giving the viewer the freedom to look around also results in a reduced ability for filmmakers to direct the viewer’s attention, a serious impediment to successfully telling a story within a 360° environment.
We have created a number of 360° clips, filmed in such a way as to demonstrate and test several unobtrusive techniques for directing a viewer’s attention within a 360° panorama. We have evaluated these techniques in a user study in which participants viewed these clips using a head-mounted display.
Qualitative and quantitative data from these tests have been analysed to evaluate the effectiveness of the different attention- directing techniques. Qualitative data was also captured to explore the effect of the camera being addressed directly, and the viewers’ responses to action occurring at a range of distances.
VISUAL ATTENTION AND CINEMATOGRAPHY
360° video is a special case of virtual reality (VR) in which the audience views a sphere (or near-sphere) of video centred on a single position. 360° formats offer the filmmaker both opportunities and challenges.
Unconstrained by a prescribed view, the viewer experiences a video environment in a way that correlates more closely to real life. However, this comes at the cost of limiting the set of techniques open to the director: the use of different camera angles and the ability to cut between them, differential focus and moving camera techniques are all constrained.
In conventional TV and film, such techniques can be used by the filmmaker to take the viewer on a specific path through a narrative, ensuring the viewer’s attention remains on the elements considered important to the story. In 360° presentation, however, the use of such techniques could have a negative impact on the user’s experience, reducing their feeling of control and potentially inducing discomfort.
Since some of the key benefits of 360° video are a result of the viewer’s control over their own gaze, the filmmaker must allow the viewer to retain that agency and direct gaze using subtler, unobtrusive techniques.
As 360° content is rapidly evolving, directors are developing a new grammar of filmmaking. In addition to accepting a lower level of control over the audience experience, the basic methods for directing attention are starting to be being explored, for example by using movement, sound and lighting cues. We seek to understand how effective some of these techniques are through more rigorous audience testing.
This paper describes the development and presentation to viewers of some specially produced 360° video material, created to allow us to probe specific directorial mechanisms for directing visual attention in 360° footage, as well as some closely related questions about the subjective experience of this kind of video. Our key research questions are:
1. What attracts attention, what refocuses attention, and what techniques can a filmmaker use to direct the attention of a viewer?
2. How does the distance at which action occurs impact the experience of the viewer?
Are presence, immersion and enjoyment affected by characters in the content addressing the camera directly? We filmed a number of one-take single-shot setups with actors. Each setup was designed to test a specific attention directing technique, or answer a particular research question.
Clips A1, A2, A3 and A4, were designed to explore directing attention, and were filmed indoors in a large gymnasium. Each clip begins with a clear element of interest, and then uses different methods to try to direct the viewer’s attention to a new element of interest introduced later in the shot.
Each clip starts with two actors, clearly in view, having a conversation; this was the only action in the scene early on, and lasted at least 45 seconds before any other cues were introduced. Thus, we could be reasonably confident that the viewers would have the opportunity to familiarise themselves with the environment, and that their attention would be drawn to (and ideally retained by) the conversation.
Another actor was introduced into an empty portion of the scene (behind the viewer if they were looking at the first two actors), and each clip used a different combination of visual and, in some cases, audio cues to direct the viewer’s attention to the newcomer.
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