Researchers use smartphone to create indoor map

A team of Swiss researchers has worked out a way to use a smartphone to create a map of the inside of a building.

According to the study’s lead author electrical engineer Ivan Dokmanic of the Swiss Federal Institute of Technology in Lausanne, an algorithm—based on the sort of echolocation that bats and dolphins use to navigate—could be incorporated into mobile phone apps to determine room dimensions for architectural or design purposes

He claims it could also be used to develop more realistic echoes in video games and virtual reality simulations and to eliminate the echo from phone calls.

Sorting out individual echoes from a recording is technically challenging and it needs microphones.

The researchers had someone stand in the centre of the room and snap their fingers or pop a balloon. Then they developed a mathematical algorithm to analyse the recordings from each microphone. Their method first eliminated echoes that had bounced off more than one wall or off small objects within the room in order to simplify the problem.

They worked out that every echo could be considered mathematically equivalent to a sound that emanated from a mirror image of the source.

This meant that they could manipulate the data that turned out to be the key to sifting through the sounds.

Dokmanic and his colleagues took the setup to Lausanne Cathedral where it was able to map the Gothic structure.

Integrating the calculations in other programs would open up real-world applications, Dokmanic says.

Mobile phone apps—requiring a few phones in one room—could be programmed to spit out room dimensions faster than it takes to pull out a tape measure and do it manually.