Smart light lets you control your environment

LiSense senses a user’s movements by utilizing shadow maps on the floor to reconstruct their 3D posture (Credit: Dartmouth College)

What if the light in the room could sense you waving your hand as you enter? And what if it responded by introducing minute light changes that instructed your smart coffee machine to switch on?

Researchers at Dartmouth College have developed a sensing system called LiSense that aims to make the light around us “smart.” Not only does it use light to sense people’s movements, but it also allows them to control devices in their environment with simple gestures, using light to transmit information.

The goal is to use light to gesture and interact with objects in a room, just like how you’d use a Wii or Kinect to interact with a TV. Xia Zhou, lead author of a paper on the research, wants to use smart light to turn every indoor space into a cognitive space.

“Using purely visible light, we can not only stay connected to the internet, but also have the environment know and respond to what we do, how we behave, and how we feel,” Zhou tells Gizmag. “Smart light can bring intelligence to all the devices immersed in the light and allow them to act based on our behaviours.”

To get LiSense to track a person’s movements only through light, the researchers built a light-sensing testbed, with LED lights in the ceiling and light sensors on the floor. The system uses the shadows cast by a person standing on the testbed to reconstruct their 3D human skeletal posture in real time. LiSense, the team states, essentially works on the same principle as a shadow puppet, where a hand held before a light blocks certain light rays and not others.

“Consider a person standing under several lights,” Zhou explains. “If we can recover the shadow cast by each light in a different direction, we can aggregate the shadow information and collect the blockage information of a large number of light rays. We then use the information to search for a 3D skeleton posture that best matches the blockage information revealed by these shadows.”

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