How a Single Screen Can Show Several Interactive Perspectives

Visiting an interactive 3-D environment is often a lonely experience. The need to wear a special headmounted display or to look at different screens means that it can be hard to interact meaningfully with other users.

That could be about to change thanks to a new technology unveiled today by Xiaolin Wu and Guangtao Zhai at McMaster University in Canada.

These guys have worked out a way for a single display to show several different image streams which the viewers choose using a controller attached to LCD glasses.

That’s possible because of relatively innocuous advances in display technology. Many displays these days are capable of showing images at a rate of 240 per second or more. Similarly, LCD glasses can match this rate.

Of course, the human visual system cannot process images at a rate higher than about 60 Hz.

So this allows several image streams to be displayed at the same time. For example, one might show the human body, another might show the vascular system, another the internal organs and another skeleton.

One viewer might select the vascular system superimposed on the skeleton. Another might want to look at the internal organs and so on.

Another option might be to show the same view from different angles. Then as the viewer moves his or her head, the perspective can be made to change.

The big advantage, of course, is that all viewers look at the same screen and so are able to discuss what they see.

A more technical advantage is that this dramatically reduces the amount of real-time processing that has to be done. All the headmounted glasses have to do is synchronise with a specific subset of images based on the user’s choice or head movement.

That has obvious applications in things like gaming and virtual tourism. It also has applications in life-critical work such as surgery, where doctors may need to interact in different ways with a 3-D data set and discuss their views.

Wu and Zhai have also identified an interesting set of security applications. Their idea is that an image can be scrambled between several streams and reassembled using a pair of encrypted LCD glasses. An eavesdropper without the glasses, on the other hand, would simply see a screen of white noise.

One application they suggest is to scramble the keys on an ATM machine so that only those wearing the glasses can see them. This would prevent an onlooker from seeing the user’s pin number.

Wu and Zhai call this process temporal psychovisual modulation and even seem to have a rudimentary version of their system working, which they show off in a video.

A potentially interesting advance.