Hardware Reference
In-Depth Information
at the sensor bar can deduce the distance and orientation of the Wiimote with re-
spect to the television. Since the sensor bar's LEDs are a fixed distance apart, their
distance as viewed by the Wiimote is proportional to the Wiimote's distance from
the sensor bar. The location of the sensor bar in the Wiimote's field of view indi-
cates the direction that the Wiimote is pointing with respect to the television. By
continuously sensing this orientation, it is possible to support a fine-grained point-
ing capability without the positional errors inherent to accelerometers.
Kinect Controller
The Microsoft Kinect takes the computer vision capabilities of game con-
trollers to a whole new level. This device uses computer vision alone to determine
the user's interactions with the game console. It works by sensing the user's posi-
tion in the room, plus the orientation and motion of their body. Games are con-
trolled by making predetermined motions with your hands, arms, and whatever else
the game designers think you should flail in an effort to control their game.
The sensing capability of the Kinect is based on a depth camera combined with
a video camera. The depth camera computes the distance of object in the Kinect's
field of view. It does this by emitting a two-dimensional array of infrared laser
dots, then capturing their reflections with an infrared camera. Using a computer
vision technique called ''structured lighting,'' the Kinect can determine the dis-
tance of the objects in its view based on how the stipple of infrared dots is dis-
turbed by the lighted surfaces.
Depth information is combined with the texture information returned from the
video camera to produce a textured depth map. This map can then be processed by
computer vision algorithms to locate the people in the room (even recognizing
their faces) and the orientation and motion of their body. After processing, infor-
mation about the persons in the room is sent to the game console which uses this
data to control the video game.
Having prepared a document or fetched a page from the World Wide Web,
users often want to print it, so many computers can be equipped with a printer. In
this section we will describe some of the more common kinds of printers.
Laser Printers
Probably the most exciting development in printing since Johann Gutenberg
invented movable type in the fifteenth century is the
laser printer
. This device
combines a high-quality image, excellent flexibility, great speed, and moderate cost
into a single compact peripheral. Laser printers use almost the same technology as
