3. – #JargonWatch Field of view (FOV)
In VR, the field of view is the open observable area a person can see, either through their own eyes or via an optical device such as AR glasses or VR goggles. As a general rule, having a wider field of view translates into more immersive experiences, which is why this aspect has been endlessly scrutinized in devices such as the HoloLens, which originally had quite a restricted FOV.
There are two types of FOV that work together to form human vision: Monocular FOV describes the field of view for one of our eyes and is the combination of three measurements. The horizontal measurement from pupil towards the nose for a healthy eye should read between 170 and 175 degrees; the nasal FOV varies between 60 and 65 degrees depending on the size of your nose; and the temporal FOV is the view from your pupil towards the side of your head and is usually 100 to 110 degrees.
We also have different FOVs for various colors but combined, these measurements mean that humans have a viewable area measuring between 200 and 220 degrees. The stereoscopic binocular field of view occurs where the two monocular ones overlap, at about 114 degrees, which as you might have guessed constitutes the 3D sweet spot where most of the action happens in both the real and virtual worlds.
Our eyes are placed about 64mm apart (again, this varies, which is why some immersive devices measure your IPD, or interpupillary distance for best results) sending different images to our brain which combines them into a single, 3D image. The greater the disparity between the two images, the greater the effect, so objects that are closer appear to have a lot of depth and objects that are far away can appear flat.
In VR, what limits our FOV is not our eyes, but the device lenses, which means that in order to get a better, more immersive view you have to either have bigger lenses or move your eyes closer to them. This is where the challenge of making smaller, less cumbersome headsets really kicks in: Using lighter, thinner lenses generally means they need to increase the distance to the VR headset display, making it bigger. Thicker lenses, however, not only add weight but tend to cause distortion. With stronger magnification, you also need higher resolution to avoid the dreaded "screen door effect" where individual pixels become visible.
The frst Wednesday of each month we’re going to dig deeper into the vocabulary of immersive tech, unpacking some of the jargon and buzzwords that get bandied about in this space. As always suggestions and feedback are welcome, just hit reply to this email!