Patent attributes
A navigation system utilizes building directories to aid navigation. A mobile device, such as a mobile phone, captures an image of a building directory. The building directory includes information regarding the names and/or locations of tenants. An image recognition algorithm is performed on the captured image to extract information from the building directory. The extracted information is used to access a map database. The mobile device may display directions or a map to guide the user to a selected destination. In addition, the captured image may be used to build the map database or update the map database. Finally, the captured image may be matched with stored images of the building directory to determine the current location of the mobile device.