Jan. 20, 2003. 07:54 AM
The translucent image of an airplane appears as a purple apparition inside Actuality Systems Inc.'s 3-D visualization technology. The unusual platform has been installed in the University of Toronto's Computer Science Department to be used for advanced research in human computer interaction.
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Gazing into the crystal ball
But what shape should the cursor be?


Tovi Grossman could be working up plans to destroy the Death Star, that spherical centrepoint of evil of Star Wars fame.

The University of Toronto graduate student stands in front of a large, spinning dome with professor Ravin Balakrishnan. The machine's eerie glow casts coloured light on their faces. A low-pitched whir, like the white noise from an industrial fan, adds to the sci-fi ambience. Inside the clear plastic dome, green and red line diagrams of simple 3-D shapes hover in space.

But the two men aren't trying to find the weak spot in the Death Star's defences. The projected images they toy with are part of their research on user interfaces for the computers of the future.

Grossman and Balakrishnan are working with the latest in 3-D display technology to determine the easiest ways for people to select and manipulate the objects displayed. The arrow-shaped cursor might seem like an obvious choice for flat computer displays today, but the point end of the arrow is only intended to designate a point on the screen with horizontal and vertical co-ordinates. A 3-D display like the one Balakrishnan works with also shows the depth of an object. It's called a volumetric display, because the objects appear to float in a volume.

To select a point on an object in a volumetric display, a user needs to indicate the depth of the point in question, as well as the height and width. An arrow-shaped cursor might not cut it.

"We might need extra cues to help us understand depth," Balakrishnan says.

Though their research is far from over, Grossman and Balakrishnan see promise in a spherical cursor. Unlike a single dot or a 2-D arrow, a spherical cursor has depth itself. Objects — or parts of objects — could be easily selected by engulfing them in the sphere. The trick, Grossman said, is designing a smart sphere, one that would automatically resize itself based on the relative size and spacing of the objects on display.

"The cursor would shrink to go between objects when they are densely packed," Grossman says.

Cursor icons shaped like crosshairs — with lines on the horizontal, vertical, and for depth — also seem to work well. The lines give the basic dot more depth.

There are other issues to be worked out, such as what kind of hardware to use to control the cursor. Since the image inside the dome can be viewed from any angle, it is likely people will want to walk around the screen as they work.

"They probably aren't going to be sitting down in a static position. Using a mouse isn't going to work," Balakrishnan says.

Balakrishnan has worked with a number of 3-D displays in the past, but his current work with Grossman is focused on a spinning, domed display made by Actuality Systems Inc.

Known as the Perspecta Spatial 3-D System, the machine has two domes: one seals the whole thing together and another inside spins. Slices of the image are projected onto a rapidly rotating screen inside the spinning dome.

"Your eye fuses the images created on the screen into a true 3-D image," says Actuality Systems' chief executive officer Cameron Lewis.

The basic, out-of-the-box machine from Actuality is output only; the cursors and selection systems, which make it more interactive, are a University of Toronto addition.

But even as a non-interactive display the Perspecta system has a variety of applications. Lewis said it could provide medical, scientific and geographic researchers with a whole new way of looking at data. Looking at medical images in three dimensions could aid in diagnosis and treatment or provide a unique perspective on the nature of a disease.

Last week, the company announced their latest customer: NASA's Ames Research Centre will be using Perspecta for their earth science and astronomy analysis. But at this point, it's still a rare, expensive device with a retail price of approximately $40,000 (U.S.). The Burlington, Mass., company has only made 13 of the displays so far. Lewis expects the price will come down over time as demand grows.

Balakrishnan says he wants to get his research going now, in part because 3-D volumetric displays are still a rarity. Now is the time to figure out the best ways to make these things work. "In some sense, we want to be pro-active because we want to develop the user interface before it's mainstream," he says.

Starting their research now — years before the product will be seen in the average workplace — gives them time to solve the problem methodically so they wind up with the best possible next-generation interface.

There's no guarantee the idea will take off, the fact that there are other companies working on 3-D display technology lends credibility to the idea that we might all be using such a system 20 years from now. VIZTA3-D, Inc., of Norwalk, Conn., makes a 3-D volumetric display that looks much more like a traditional computer monitor than Actuality's crystal ball. Unlike a conventional, single-screen 2D computer monitor, VIZTA3-D's Z 20|20 system employs 20 liquid crystal display screens stacked together to give a sense of depth.

Balakrishnan said each system has its own advantages. In his experience, stacking the screens causes interference. On the other hand, those images sometimes look more realistic because they appear more solid.

The images on an Actuality display are always going to be somewhat translucent because of its special projection system. Holographic systems — yet another option for future 3-D displays — have the advantage of added interactivity: you can put your hand right into the image.

In the end, it's all just a trick of the eye.

All three methods try to fool your eyes using a fundamental concept of human vision: the stereoscopic perspective.

The principles of stereoscopic vision have been understood since the time of the ancient Greeks. In 1832, Sir Charles Wheatstone invented a tool that exploited the idea in a practical way.

His device, the stereoscope, used two nearly identical pictures and a special pair of glasses. For an old fashioned stereoscopic image, two pictures are taken a few centimetres apart.

The glasses separate the two images so only the left eye views the picture on the left and the picture on the right is viewed only by the right eye. The slightly different perspectives the human eye sees are re-created, and the image appears three-dimensional.

Those who had the pleasure of using the special glasses were amazed. But like the new 3-D displays, early stereoscopes weren't cheap. They were ornate devices, with the glasses sometimes made out of carved wood.

It wasn't until Oliver Wendell Holmes devised a cheaper way to make the viewing glasses in the 1860s that they hit the mass market. You could call it the must-have for the home entertainment centre of the late 19th century. In fact, up until the 1920s collecting stereoscopic images was a very popular hobby.

From still pictures, the concept of 3-D made its way to movies. As early as 1915, moviegoers were being treated to 3-D entertainment.

The Viewmaster — those little plastic toys with the circular discs from childhood — is a stereoscopic viewer that works in the same way. The early Viewmasters of the 1930s weren't toys at all. They were designed as a successor to Holmes' stereoscope, with the notable improvement of including seven stereoscopic images per disc.

A switch in demographics produced a shift in the images sold. The company moved from producing the usual stereoscopic fare — such as landscapes and romantic scenes — to popular cartoon characters.

The concept was a hit with kids in the 1960s and '70s. Slides were made of most Disney characters and Mickey's Mouseketeers had their own reels.

Perhaps the makers of modern 3-D viewers should take note. Forget the medical and geological applications.

There could be a burgeoning market for computerized 3-D cartoon displays.

And with the right kind of cursor, we'll have no problem picking up Annette.

Rachel Ross deconstructs technology most Mondays in @Biz. Reach her at rross@thestar.ca

Additional articles by Rachel Ross

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