Called Aquatop, the combination allows people to use more interactive gestures than the usual tapping and swiping methods typical of touchscreen devices. With the Kinect sensor, users can scoop, drop, dunk and pull media.
But for the sensor to work, the water must be opaque. Mixed with bath salts, the water becomes milky-white and provides better contrast as a projection surface.
The opaque water reflects the infrared light emitted by a Kinect depth camera, which is responsible for tracking the position of multiple fingers – whether you hold them above the water, touch the surface from above or poke them out from beneath the surface. Both the Kinect camera and the projector are connected to a single PC. The images are projected onto the surface of the water.
This configuration allows for several innovative interaction modes, impossible to achieve with standard displays, such as scooping up a handful of water with a video thumbnail projected on its surface and then dropping the thumbnail over a video player area to start the video in full screen (or full bath) mode.