Google has released a prototype smartphone that can create 3D maps of a user's surroundings.

The company believes that the technology, which is eerily similar to the sonar app in the The Dark Knight, could be used for things like helping blind people to get around, and for 3D indoor gaming.

Professional developers have been asked to submit ideas for the kind of apps they would make for the phone.

The phone, named Project Tango, can make over a quarter million 3D measurements every second, updating its position and orientation in real-time, combining that data into a single 3D model of space.

In Christopher Nolan's second instalment of the Batman reboot, The Dark Knight, Batman (Christian Bale) is aided in foiling the Joker (Heath Ledger) using mobile phones as 3D mapping devices.