Water Droplets Create Multilayered DisplayS

Click to viewWaterfalls have never been this much fun. Sheets of cascading droplets have been turned into a multilayered computer display, suitable for playing Tetris in 3D.

Peter Barnum, Srinivasa Narasimhan and Takeo Kanade at Carnegie Mellon University in Pittsburgh, Pennsylvania, have projected images onto a series of water screens, one behind the other, to give depth to the image.

Each screen is formed by water droplets falling from 50 stainless-steel needles. The needles release their droplets in unison, with 60 such lines created every second. A camera tracks their position and feeds the information to a projector, which illuminates them with pulses of light. The human eye integrates the information from several pulses to create the illusion of images moving on a floating screen.

The team used four parallel sets of needles, computer-controlled to release their lines of droplets at slightly different times so the droplets in one vertical layer do not obscure those in the other layers.

"A single projector, by quickly switching between images, can display on different layers at different times," says Barnum. "Anything you can have with a computer, like images, text, movies, or anything interactive, you can have on the drop display."

Higher resolution:
Although other waterfall display systems exist, the team says the new multilayered setup requires less manual operation and offers higher resolution than has been achieved previously.

"This falls into a new category of display technologies," says Roel Vertegaal of Queen's University in Kingston, Ontario.

As well as having possible artistic applications, Vertegaal speculates the display might be useful in operating theatres. "If you could sterilise the water you could have a completely antiseptic environment and you could still project 3D images on it."

Barnum's team will present their work at the annual computer graphics conference SIGGRAPH in Los Angeles next month.

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