Sarah Zhang in Wired:

Humans, quite simply, suck at walking in straight lines: Give a man a blindfold, and he will walk around in circles. In virtual reality, though, this failing becomes very convenient. People are so bad at knowing where they are in space that subtle visual cues can trick them into believing they’re exploring a huge area when they’ve never left the room—a process called redirected walking.

With VR technology getting ever better, people could one day explore immersive virtual spaces—like buildings or even whole cities—on foot in head-mounted displays. But it’s not very immersive if you end up smacking into a real-life wall. “This problem of how you move around when in VR is one of the big unsolved problems of the VR community,” says Evan Suma, a computer scientist at the University of Southern California.

That’s where redirected walking comes in. People don’t really notice, it turns out, if you increase or decrease the virtual distance they had to walk by 26 percent or 14 percent, respectively. Or shift the virtual room so they see their path as straight when their real path is curved. Or turn the room up to 49 percent more or 20 percent less than the rotation of their heads.