Using the space on and above the back of the hand to operate smart devices

May 05, 2017 // By Jean-Pierre Joosting
Using a depth sensor that tracks movements of the thumb and index finger on and above the back of the hand, researchers have developed a method that can control smartwatches as well as smartphones, smart TVs and devices for augmented and virtual reality.

They're called the "Apple Watch Series 2", "LG Watch", "Samsung GEAR S3" or "Moto 360 2nd Gen" but they all have the same problem. "Every new product generation has better screens, better processors, better cameras, and new sensors, but regarding input, the limitations remain," explains Srinath Sridhar, a researcher in the Graphics, Vision and Video group at the Max Planck Institute for Informatics. 

Together with Christian Theobalt, head of the Graphics, Vision and Video group at MPI, Anders Markussen and Sebastian Boring at the University of Copenhagen and Antti Oulasvirta at Aalto University in Finland, Srinath Sridhar has developed an input method that requires only a small camera to track fingertips in mid-air, and touch and position of the fingers on the back of the hand. This combination enables more expressive interactions than any previous sensing technique.

Regarding hardware, the prototype, which the researchers have named "WatchSense", requires only a depth sensor, a much smaller version of the well-known "Kinect" game controller from the Xbox 360 video game console. With WatchSense, the depth sensor is worn on the user's forearm, about 20-cm from the watch. As a sort of 3D camera, it captures the movements of the thumb and index finger, not only on the back of the hand but also in the space over and above it.

The software developed by the researchers recognizes the position and movement of the fingers within the 3D image, allowing the user to control apps on smartphones or other devices. "The currently available depth sensors do not fit inside a smartwatch, but from the trend it's clear that in the near future, smaller depth sensors will be integrated into smartwatches," Sridhar says.


A novel input method expands the input space to the back of the hand and the 3-D space above it. Image courtesy of Oliver Dietze.