Virtual reality (VR) has been a fantasy of many people since computers had appeared and it had always seemed just behind the corner. Lately, several companies started promising new HMDs (head mounted displays) that should give us nice 3D view for the most immersive experience ever. Several months ago we've heard some hints that Valve may also be working in that direction. While we don't have any official announcements, the topics in Michael Abrash (R&D at Valve) blog clearly show that company is researching such technology.

In his latest blog, the latency is mentioned as very important factor that decides if the result is believable. While we may get 30-50ms latency between input and seeing result of it in games and that would give us a quite smooth experience, the requirements for believable VR or AR (Augmented Reality) are more strict. We are very good at noticing quickly changing things, so any system that tries to replace our reality with an artificial one must react faster than we can notice. Abrash puts 20ms latency as upper limit and 7 ms as an ideal case. Graphics should be rendered at 200FPS or more to get near good scenario which would mean 5 year old graphics (like consoles) on modern PC hardware or something from 2000, if we want a portable system with mobile phone GPU. Another problem that may not be solved so easily is the usage of 60Hz phone displays in HMDs – 120Hz or faster would be better. Overall, the problems boil to getting the combination of speed, resolution, FOV and price, as the requirements for HMDs, are quite different from existing devices.

Michael Abrash's blog contains more interesting and detailed posts about the possibilities and issues of VR and AR, and I recommend reading it for those who are interested in such technology. Who knows, maybe in some years we'll be looking at reviews comparing Google Glass against SteamView headsets.