Aqualux 3D – a multi-layered display with water drops

We already wrote an article where water droplets (or fog) were used as a medium where image was projected in order to create interesting walk-through and semitransparent displays (see our article regarding FogScreen eZ). A new projection technology, developed at Carnegie Mellon University’s Robotics Institute, is named AquaLux 3D and it can target light onto and between individual water droplets.  By targeting between individual droplets, this technology enables text, video and other moving or still images to be displayed on multiple layers.

The researchers said that the work on the display technology was an outgrowth of efforts to develop an LED automobile headlight system for driving in rain at night. They explored ways to control light so that as many rays as possible would shine between raindrops in order to eliminate the headlight reflection that occurs in rainy conditions.

“In contrast to existing technologies for projecting images onto water surfaces, AquaLux 3D makes it possible to create three-dimensional images in water by using multiple layers of precisely controlled water droplets,” said Srinivasa Narasimhan, associate professor of robotics. “By combining the droplets with clouds of mist, it would be possible to create unique 3-D effects for theme parks, exhibitions and interactive games that don’t require special eyeglasses to view.”

To accomplish this they developed a tightly coupled system that enabled them to generate rows of drops by using computer-controlled manifolds. By synchronizing the timing of drop generation between the rows, they ensured that drops in the front rows did not block the drops in the back rows. A camera tracks the positions of the drops, so a projector can independently target each row.

“The beauty of water drops is that they refract most incident light, so they serve as excellent wide-angle lenses that can be among the brightest elements of an environment,” said Narasimhan, who developed the display with Takeo Kanade, professor of computer science and robotics, and Peter Barnum, a Ph.D. student in robotics. “By carefully generating several layers of drops so that no two drops occupy the same line-of-sight from the projector, we can use each drop as a voxel that can be illuminated to create a 3-D image.”

The system can generate drops at the rate of 60 per second, though a rate of 10 per second is sufficient for the human eye to perceive continuous resolution in each column. The increased number of drops per second was used in order to increase the brightness of the display. The researchers have demonstrated the display with four linear layers of drops and a single projector, but Narasimhan said there is no limit to the number of layers and projectors that could be employed and that the drops could be arrayed in patterns other than linear rows.

The researchers have used the water drops to display video images, text, a simulation of fish swimming in an aquarium, alternating sheets of solid colors and even a multi-dimensional version of the video game Tetris. Since the AquaLux 3D has the potential to incorporate the physical interaction, the developers hope that other creative people could use their display as a new platform for games and marketing.