Friday 7 August 2015

Stanford And Nvidia Team Up On More Realistic 'Light Field' VR Headset

While virtual reality may not be mainstream, there are lots of promising devices on the horizon, and there’s still lots of work to do.
Researchers at Stanford University and Nvidia are making a contribution to the technology with a virtual reality prototype that uses light field technology — which describes how light flows through a single point in every direction — to mimic how each eye focuses on objects based on distance.
Typically, virtual reality headsets create the illusion of 3D using a “stereoscopic” technique that puts two separate images in your eyes with slightly different angles. But the images are flat and that can create strain on the user’s eyes.
“The way we perceive the natural world is much more complex than stereoscopic,” Gordon Wetzstein, an assistant professor of electrical engineering at Stanford, said in an interview. ”Our eyes can focus at different distances. Even one eye can see in 3D. It does that by focusing the eye.”
What the Stanford and Nvidia’s prototype does is create a sense of depth in each eye and combines it with the stereoscopic technique of showing images at slightly different angles in each eye. The prototype uses two transparent LCD screens layered on top of each other that produce the light field affect. Each eye is shown a combination of 25 images through the layered LDC screens to give the sense of depth. It’s sort of like putting a hologram in front of each eye.
Schematic of how the prototype is assembled.

This technique allows the user to look around the virtual world and see depth.
The virtual reality prototype is attached to a desktop PC equipped with Nvidia’s Maxwell graphics card architecture. The algorithm used to compute all the images in the headset is based on Nvidia’s CUDA programming language.
The secretive startup Magic Leap — which is building an augmented reality headset, not virtual reality — also claims it uses some sort of light field technology to reproduce realistic digital objects, but the company hasn’t made any details public on how it accomplishes this.
But creating a sense of depth isn’t the only challenge for virtual reality devices. Headsets also need to have extremely high resolution and as little latency as possible between when someone moves their head and what shows up in the headset. Using mostly off-the-shelf hardware, Wetzstein’s virtual reality prototype isn’t able to provide very high resolution and low latency. With billions from Facebook, the latest versions of the Oculus Rift headset shown to the public reportedly have solved these problems around resolution and latency.
Wetzstein has been working on light field display technologies since 2010, but only started working on this prototype a year ago when he joined Stanford. Wetzstein will be presenting a paper and giving demonstrations of the prototype next week at the SIGGRAPH 2015 Emerging Technologies conference. The prototype the researchers will be presenting is a third generation version. “This is as good as we can make it from off-the-shelf components purchased on eBay EBAY +0.00% and 3D-printed housing,” Wetzstein said.

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