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The device uses its inbuilt GPS system to search for augmentations associated with particular coordinates.  As this is relatively coarse, this is usually supplemented with Wi-Fi, mobile phone towers, compass, accelerometer and gyroscope measurements. Newer applications are marrying such location geopositioning techniques with vision techniques to improve accuracy.

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The increased use of sensors built into our mobile networked environments is expected to add the use of microphones, accelerometers and clocks to the sensor set.

SLAM (Planar Surface detection)

SLAM (Simultaneous Localization and Mapping) is a technology which interprets the physical world through features in a 2D image.
AR applications can thus overlay digital AR augmentations on flat (or other) surfaces and control dimensions in relation to their interpreted environment.

Expressions (Output)

There are three basic modes through which output is expressed in AR environments: visual, auditory, and haptic. 

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