Changes

===The Touring Machine===

===The Touring Machine===

Feiner and colleagues create the first outdoor AR system, at Columbia University. The Touring Machine (Figure 3) had a see-through HMD, GPS, and orientation tracking. The system needed a backpack with a computer to deliver mobile 3D graphics, various sensors, and an earlier version of a tablet computer for input.<ref name=”3”/>

Feiner and colleagues created the first outdoor AR system at Columbia University, called the Touring Machine. It had a see-through HMD, GPS, and orientation tracking. The system needed a backpack with a computer to deliver mobile 3D graphics, various sensors, and a version of a tablet computer for input.<ref name=”3”/>

===ARQuake===

===ARQuake===