When you consider the features of a virtual reality headset, what do you look for? Field of view, lightweight design and high resolution are at the top of most users requirements.

The virtual reality headset (often abbreviated HMD for Head Mounted Display) fits, obviously, on the head, much like sunglasses or a visor. It will have either one small display lens to cover one eye, or two to cover both eyes. The lenses will display in 3D the elements of the virtual reality environment.

In this headset, there are two types of vision models: the kinds with and without a tracking system. Without the tracking system, one would see the same image in the headset, no matter which way one’s head is turned.

A (HMD)with a tracking system is sophisticated enough to make note of the angle and position of the head and adjust the virtual image accordingly. Eye tracking technology is used to note where the user is looking and bring that area into better focus. For this reason, the average inter-pupillary distance in humans is used to coordinate the eye trackers in the virtual reality headset.

Some VR headsets are designed to show a computer generated image or a real-world view from somewhere else. Some are sophisticated enough to overlay a CGI display over a real world view. This is called the optical see-through version.

The field of view that humans naturally experience is a whole lot smaller in the virtual reality headset. Humans have a field of view, expressed in degrees, of 180. So, the greater the field of view of a typical virtual reality headset, the more in depth the image will be. However, as most people aren’t really aware of what, say, a 25 degree FOV would be like, manufacturers and merchandisers will often refer to the FOV of a given model of virtual reality headset in terms that people do understand. It will be quoted as the size of a monitor or television screen.

The greater the field of view, the better the sense of immersion into the VR environment. A narrow field of view eliminates peripheral vision and will not render a satisfactory experience.

And what about the resolution of a virtual reality headset? As with computers monitors, this figure is again quoted in computer terms, i.e., in pixels. A VR headset might be said to have a resolution of, say, 1920 X 1600 pixels. As for pixel density, between 10-20 pixel per degree is good. The higher the number, the better pixel density for resolution in the virtual reality headset.

(HMD)s are advanced enough, now, to be run by the average home computer, as long as it is equipped with a power graphics card. Other input devices should be compatible with the headset to ensure a good experience.