Latency is the biggest stumbling block when it comes to virtual reality, according to Valve engineer Michael Abrash. The “holy grail” of virtual reality is a 7ms latency, which just isn’t feasible with current technology — not yet, anyway.
“For reference, games generally have latency from mouse movement to screen update of 50 ms or higher (sometimes much higher), although I’ve seen numbers as low as about 30 ms for graphically simple games running with tearing (that is, with vsync off),” says Abrash. “In contrast, I can tell you from personal experience that more than 20 ms is too much for VR and especially AR, but research indicates that 15 ms might be the threshold, or even 7 ms.”
“AR/VR rendering on PCs will have to be roughly on the order of five-year-old games, which have low enough overall performance demands to allow rendering latencies on the order of 3-5 ms (200-333 Hz). Of course, if you want to do general, walk-around AR, you’ll be in the position of needing to do very-low-latency rendering on mobile processors, and then you’ll need to be at the graphics level of perhaps a 2000-era game at best. This is just one of many reasons that I think walk-around AR is a long way off.”
Take a read of the full post over at the official Valve blog.