The team at BBC Research and Development have developed a system to capture, edit and render single-camera light field backgrounds that could be used in virtual TV production.
In a blog post, BBC R&D senior technologist Florian Schweiger said the team used a 360-degree camera to capture panoramic images are each from a single viewpoint.
They then used a motorised rig that slowly moves the camera around a horizontal circle, with a complete revolution taking 30 seconds. During that time, it recorded exposure-locked video at 60 frames per second, resulting in a dataset that contains 1800 frames, or five frames per degree.
“A typical diameter for the capture circle is one metre, which means that we effectively capture views less than 2mm apart,” explained Schweiger. “We can then synthesise views for virtual camera positions anywhere inside the capture circle from this dense set of source views.”
The team had to ensure that the scene remained perfectly still while the camera moved in order to avoid ghosting artefacts that would appear in views synthesised from inconsistent data.
“While this excludes certain use cases, it is rarely an issue for our purpose of creating backdrops for virtual reality that can then be populated with animated characters,” added Schweiger.
“Another difference to a full light field with six spatial degrees of freedom (6 DoF) is that our array of source views is only one-dimensional,” he continued. “All captured viewpoints lie on a line (albeit a bent one: the capture circle), but there aren’t any viewpoints in our dataset that would cover the vertical direction. Consequently, a viewer only has five truly free degrees of freedom – three to turn their head and two to move in the plane of the capture circle. Moving up or down, however, they will not perceive vertical parallax as they would in real life.”
Schweiger explained that this is generally acceptable because horizontal parallax tends to be more important for human stereo vision due to the relative position of the viewer’s eyes.
The light field solution is currently at the prototype stage, running on standard gaming PC hardware.
According to Schweiger, the requirements for virtual TV are very different, with the resolution needing to be significantly higher in order to meet broadcast standards.
The full blog post, including information on rendering and editing, is available here.