Specifications

The DK1 model includes three pairs of lenses, pictured in Figure 1.14. The pairs are all

identical in terms of how they transmit light. How they differ is that they place the lens at

slightly different distances from the actual LCD display. (You can see this in Figure 1.14 by

comparing their heights; the “C” lenses are visibly shallower than the “A” lenses.) Combined

with the headset distance adjustment knobs, this allows the user to vary the distance between

the screen and the lenses, as well as the lenses and the eyes, in order to accommodate a wide

variety of facial characteristics as well as users who require prescription glasses.

Note that the current model does not allow you to change the distance between the lenses.

It is fixed at 64mm apart. However, this isn’t as much of an issue as one might suspect. The

lenses are designed to present the same image to the user regardless of where exactly the

eyes are located. If you move an image-capturing device (your eye, for instance) off the

center axis of the lens, the image captured does not itself move laterally. As long as they’re

within a volume about 1.5x1.5cm across and 0.5cm deep, barring a small amount of distortion

at the edges, your eyes will perceive the same image from the screen, with the same pixel

appearing ‘directly ahead’. This allows the Rift to support a broad swath of users with varying

inter-pupillary distances. This remarkable property is called collimated light and will be

discussed in detail in Chapter 4.

1.3.3 The GPU

It’s worth touching on one additional component essential to the operation of the Rift which

isn’t included in either kit: the GPU. Every modern personal computer today includes a

Graphics Processing Unit with a programmable pipeline. This remarkable piece of technology is

an integral part of what makes the Oculus Rift possible.

1.4 How the Rift Works

Virtual reality is about constructing an experience that simulates a user’s physical presence in

another environment. The Rift accomplishes this by acting both as a specialized input device

and a specialized output device.

As an input device, it uses a combination of several sensors to allow an application to query

for the current orientation and position of the user’s head. This is commonly referred to as the

head pose. This allows an application to change its output in response to the changes in where

the user is looking or where their head is.

Head pose

In VR applications, a head pose is a combination of the orientation and position of the head relative to

some fixed coordinate system.

As an output device, the Rift is a display that creates a deep sense of immersion and

presence by attempting to more closely reproduce the sensation of looking at an environment

as if you were actually there, compared to viewing it on a monitor. It does this by

other simple mistakes. These will be cleaned up during production of the book by copyeditors and proofreaders.

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