17 June 2011
Can You Find Me Now?
How is a Nintendo Wii game console able to determine the location of a Wii Remote while a player interacts with a game? The answer is Triangulation, a process that determines the location of an object by measuring the angles from two of more fixed points. Surveyors often use triangulation to measure distance. Starting at a known location and elevation, surveyors measure a length to create a base line and then use a theodolite to measure an angle to an unknown point from each side of the base line [ (Jains 30-48) ]. The length of the base line and the two known angles allow a computer or person to determine the location of a third point.
Similarly, the Nintendo Wii game console uses triangulation to determine the location of a Wii Remote. A player places a sensor bat, which contains two infrared transmitters, near or on top of a television. While the player uses the Wii Remote, the Wii game console determines the remote’s location by calculating the distance and angles between the Wii Remote and the two transmitters on the sensor bar. Determining the location of a Wii Remote is relatively simple because the sensor bar contains only two fixed points: the transmitters.
A more complex application of triangulation occurs in a global positioning system (GPS). A GPS consists of one or more earth-based receivers that accept and analyze signals sent by
satellites to determine a receiver’s geographic location. GPS receivers, found in handheld navigation devices and many vehicles, use triangulation to determine their location relative to at least three geostationary satellites. According to Sanders, the geostationary satellites are the fixed points in the triangulation formula [ (Understanding Satellites and Global Positioning Systems) ].
The next time you pass a surveyor, play Nintendo Wii, or follow a route suggested by a vehicle’s navigation system, keep in mind that none of it...