The lightweight bracelet allows for free movement. (Credit: Fang Hu/Cornell)

A wrist-mounted device continuously tracks the entire human hand in 3D. The bracelet, called FingerTrak, can sense and translate into 3D the many positions of the human hand, including 20 finger joint positions, using three or four miniature, low-resolution thermal cameras that read contours on the wrist.

The lightweight bracelet allows for free movement. Instead of using cameras to directly capture the position of the fingers, the focus of most prior research, FingerTrak uses a combination of thermal imaging and machine learning to virtually reconstruct the hand. The bracelet’s four miniature, thermal cameras — each about the size of a pea — snap multiple “silhouette” images to form an outline of the hand.

A deep neural network then stitches these silhouette images together and reconstructs the virtual hand in 3D. Through this method, the researchers were able to capture the entire hand pose, even when the hand is holding an object.

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