Human Computer Interaction researcher Elke Folmer, based out of the University of Nevada, Reno, has developed an interior navigation system for people with little or no sight. Instead of relying on expensive sensing equipment or augmentations to the building in which the device is used, Navatar uses accelerometers, a low cost technology available in smartphones.
Indoor navigation is made more manageable by the infrastructure of the building. Users are limited by hallways and doors, and are less likely to veer as they would outdoors. Typically, to generate a precise layout of the area, Radio Frequency Identification (RFID) tags are used. These devices combine an antenna and compass into a small package for use with other technologies. However, they are very expensive to implement.
Navatar uses what's known as Dead Reckoning, a less precise but less expensive technology, in conjunction with a virtual rendering of the building being navigated, and the users' confirmation of the presence of tactile landmarks as they navigate. Using a virtual rendering created by such products as Google's Sketchup, a user can receive step by step navigation via their phones.
Check out this video of Navatar in use. For more information Folmer's website.