Video: Table top to share

Two’s company (Image: Dr Jean-Baptiste de la RiviÃdre)

Two of today’s most popular technologies, 3D imagery and multi-touch screens, are brought together for the first time in this display.

Both are becoming increasingly common in everyday life, with immersive 3D movies hitting our screens and gadgets such as the iPad making touchscreens that recognise gestures commonplace. But why has it been so hard to bring the two together?

One obstacle is that immersive 3D technologies are designed to be looked at, not touched. The images in 3D movies seem to be coming out at you, but trying to touch them would ruin the illusion, as your hand will pass straight through.


Now Jean-Baptiste de la Rivière and colleagues from Immersion, a visual simulation company based in Bordeaux, France, have at last managed to combine the two technologies into an interactive 3D table-top display.

Visitors to the SIGGRAPH computer graphics and animation conference in Los Angeles last week were invited to don polarised glasses that allowed them to interact with a 3D cityscape projected onto the table. What they saw changed to match their point of view.

Better still, two users viewing the same model city at the same time from different sides of the table could each see the 3D effect with the correct perspective for their position.

That’s because the glasses are wired to position and orientation sensors that track the wearer’s gaze, and the system uses this information to alter the image accordingly in real time for each user.

The polarised glasses contain an active shutter system that is synchronised to the table-top display as it rapidly alternates between the images to match each user’s perspective. The glasses transmit images that match their perspective, but block images that match the other user’s perspective.

Importantly, users can also interact with the display when they touch it, to zoom in or rotate the buildings, for example, without breaking the 3D illusion.

To do this, the system makes images that seem to rise above it when a person is simply looking at it, but when the viewer try to touch the 3D buildings they appear to be lower – “right inside the table”, the researchers say. The display knows when a hand is coming near it thanks to infrared sensors, which respond before the fingers reach the surface and break the depth illusion.

See more: Beyond the touchscreen: Projecting the future