Know why you do not bump into someone as you walk in a crowd where everyone seems to be moving in a coordinated way? The answer lies in a virtual crowd.
Researchers have developed a wireless virtual reality system to understand patterns of crowd movement to reveal the science of the swarm.
It is an everyday experience for all kinds of animals, including ants, birds, fish and people.
"When you walk across campus during class change you are, consciously or not, coordinating your movements with the people around you," said professor William Warren from the virtual environment navigation lab at the Brown University in the US.
"In some situations, coherent 'swarms' form, somewhat like a flock of birds or a school of fish. We wanted to understand that process," he added.
To make this possible, Warren and his team rigged up the 168-square metre VENLab to make their off-the-shelf "Oculus Rift VR" headsets wireless.
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The room also has video cameras and a grid of beacons on the ceiling that emit ultrasound pulses denoting their location.
The headset "listens" for those beacons with microphones and combines them with signals from accelerometers, much like the ones in a smartphone.
A well tuned computer model of such swarming behaviour could have many specific applications in human life.
It could also lead to technology to help visually impaired pedestrians.
"In experiments, we can manipulate a virtual crowd to see how real subjects respond to the behaviour of their virtual neighbours. This allows us to model the visual coupling between an individual and their neighbours," Warren explained.
Now, researchers are mapping out what they call the "coupling field" that connects you to neighbours at different distances and different positions.