Everything You Probably Didn’t Know About FOV In HMDs

VR headsets have been seeing new life for a few years now, and when it comes to head-mounted displays, the field of view (FOV) is one of the specs everyone’s keen to discover. Valve Software have published a highly technical yet accessibly-presented document that explains why Field of View (FOV) is a complex thing when it pertains to head-mounted displays. FOV is relatively simple when it comes to things such as cameras, but it gets much more complicated and hard to define or measure easily when it comes to using lenses to put images right up next to eyeballs.

Simulation of how FOV can be affected by eye relief [Source: Valve Software]
The document goes into some useful detail about head-mounted displays in general, the design trade-offs, and naturally talks about the brand-new Valve Index VR headset in particular. The Index uses proprietary lenses combined with a slight outward cant to each eye’s display, and they explain precisely what benefits are gained from each design point. Eye relief (distance from eye to lens), lens shape and mounting (limiting how close the eye can physically get), and adjustability (because faces and eyes come in different configurations) all have a role to play. It’s a situation where every millimeter matters.

If there’s one main point Valve is trying to make with this document, it’s summed up as “it’s really hard to use a single number to effectively describe the field of view of an HMD.” They plan to publish additional information on the topics of modding as well as optics, so keep an eye out on their Valve Index Deep Dive publication list.

Valve’s VR efforts remain interesting from a hacking perspective, and as an organization they seem mindful of keen interest in being able to modify and extend their products. The Vive Tracker was self-contained and had an accessible hardware pinout for the express purpose of making hacking easier.  We also took a look at Valve’s AR and VR prototypes, which give some insight into how and why they chose the directions they did.

InfinitEye HMD Brings 210 Degree FOV To The Party

Head mounted displays are coming in hot and heavy this year. InfinitEye doesn’t have an official web page yet, so we’re linking to a review done by TheRoadToVR. Note that this is the second version of the display. InfinitEye released plans for their V1 HMD back in February. The InfinitEye prototype looks strikingly like the early Oculus Rift prototypes. Gaffers tape and what appears to be the frame from a face shield hold together the optical system. It’s this optical system which is interesting. InfinitEye has decided to go with head mounted LCD screens, similar to the rift, and unlike castAR’s projection system.

The InfinitEye team decided to go with two screens, giving them a whopping 1280×800 resolution per eye. The optics are also simple – fresnel lenses. This is all similar to the first version of the goggles, however the InfinitEye team claims that this new edition provides a 210 degree field of view. What we don’t know is exactly what they changed. We’re curious if the wider field of view will reduce the Sim Sickness some of us have felt with the rift – though to be fair, almost any head mounted display requires some time to adjust. What we are sure of is that the future is bright for virtual (and augmented) reality.

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