News in Science

Future 6D holograms interact with light

The basic technology used in cheap 3D postcards and novelty items has been adapted to create six-dimensional images that respond to changes in light and the viewer's direction.

While the display is still pretty small, seven by seven pixels, the researchers hope that within the next two to three years they could scale it up to create some of the most realistic images available.

"We are the first ones to build a display that changes with lighting," says Associate Professor Ramesh Raskar, a scientist at Massachusetts Institute of Technology who helped to develop the technology. "We've finally found a way to build the most realistic display."

The idea is similar to the technology used on stiff, cheap plastic postcards, the kind when rotated causes an image to move or make it 3D.

These postcards use a series of raised parallel lines to create tiny lenses that project different images at either vertical or horizontal angles. The effect can make an image of a car appear like it's moving down a road or a hand appear like it's waving as you tilt the card one way and then another.

Instead of using parallel lines to create the image, the researchers used squares to create lenses that present different images at both vertical and horizontal angles simultaneously.

Responsive

It's not all about the light coming out of the display though. Unlike a television, where information only goes in one direction, the 6D display would respond to changes in the illumination around it, like passing shadows or bright highlights.

Imagine two flowers side by side, one real, one holographic, says Raskar.

"They would both look real," he says. "But if you shine a flashlight on the hologram, light would pass right through it while the real flower would change in response to the light."

Using their new technology, the image the scientists create would actually respond to light like a real flower would.

To demonstrate their design, the scientists created a 6D image of a wine bottle in the display and showed the device at the recent SIGGRAPH (Special Interest Group on GRAPHics and Interactive Techniques) conference.

While the small prototype was a success, don't expect to see the technology for a few years. The scientists say the technology is still at least two to three years away from realistic use.

It's also expensive. Because they use custom made parts, the displays currently cost about $US30 per pixel.

Novelty item

Mass production could lower that cost, but creating even a 100 by 100 pixel image viewable from 10 different angles would take 100 million different pixels, says Dr Alan Sullivan, a research scientist at Mitsubishi Electric Research Laboratories who also built a sophisticated 3D DepthCube Display.

Sullivan sees 6D displays first being used by science museums as novelty items. Once the technology matures it could be used for high-end applications, "where a lot of money would go into something and no one wants to make a bad decision during the design phase," says Sullivan.

Some of the areas Sullivan envisions for 6D displays include new cuts for precious stones, vehicles with paints that change color depending on the angle, and buildings whose appearance would change depending on the position of the sun.

"I love this technology," says Sullivan. "I think it's a cool idea, and even if its ultimate implementation isn't done, it's inspirational. If we don't reach for the stars we can't get off the ground."