It is through a quirk in human physiology referred to as ‘persistence of vision’ that humans are able to perceive a rapidly moving series of still images as being in motion. This quirk resulted in the creation of cinema, followed by television and videogames and, ultimately, virtual reality (VR). Unfortunately, another quirk of human physiology can lead to the scourge of VR developers, simulation sickness. A study from Brunel University London investigates if what steps can be taken to minimise this effect.
Researchers at Brunel University London, Thorsten Roth and Dr Yongmin Li of the Department of Computing along with collaborators at the Bonn-Rhein-Seig University have been studying the impact that foveated rendering can have on symptoms of simulation sickness such as nausea and dizziness.
Foveated rendering is a technique that tracks where the user is looking and only renders the area they are looking directly at in full detail, with everything else being blurred. This has been mostly aimed as reducing the amount of system resources needed to create VR worlds in realistic detail, but also has potential elsewhere.
“We use a method where, in the VR image, detail reduces from the user’s point of regard to the visual periphery,” explained Mr Roth, “and then our algorithm – whose main contributor is Mr Weier –then incorporates a process called reprojection. “This keeps a small proportion of the original pixels in the less detailed areas and uses a low-resolution version of the original image to ‘fill in’ the remaining areas.”
The researchers investigated three different sizes of area that remained in sharp detail, small, medium or large, covering the ‘foveal’ area at the centre of vision. Each study participant wore a specially adapted Oculus DK2 headset and viewed 96 VR videos, each one eight seconds long and consisting of a variety of subjects, eye movements and varied types of foveated rendering. The study found the the medium amount of sharp detail proved to be ideal for reducing simulation sickness symptoms whilst keeping immersion intact.
Mr Roth commented: “We showed that it’s not possible for users to make a reliable differentiation between our optimised rendering approach and full ray tracing, as long as the foveal region is at least medium-sized.”
You can watch a video of the Brunel University London foveated rendering techniques in action below.
VRFocus will continue to report on new studies and research in the field of VR.