Uncross those eyes: Researchers solve VR’s depth-of-focus headaches

For anyone used to the limited 3D effects created with diffusing glasses and standard flat displays, the sense of depth provided by a stereoscopic VR headset is an impressive improvement. But trying to switch your focus between objects at different virtual distances can still be an eye-crossing, headache-inducing experience with these flat-panel displays. A team of researchers at Stanford University recently published an interesting potential solution to this problem, using a couple of layered LCD screens to provide real-world depth cues in a small VR headset form factor.

The main problem with depth focusing in traditional stereoscopic HMDs is that, despite fancy lensing and left/right eye image separation, you're still looking at a flat panel placed very close to your face. Trying to focus on "far away" objects on that stereoscopic screen means keeping a fixed focal distance but changing the "vergence" angle of your eyes—in essence, going a little cross-eyed for a moment. That can lead to "visual discomfort and fatigue, eyestrain, diplopic vision, headaches, nausea, compromised image quality, and it may even lead to pathologies in the developing visual system of children," the Stanford researchers write.

In addition, a traditional display doesn't know where you're looking at any point. That means the system cannot determine which parts of the image should be rendered with the slight "retinal blur" that applies to out-of-focus objects in our real-world vision. Paradoxically, having the entire virtual world be perfectly "in focus" on that LCD display makes things seems a little less real.