3-D Vision Speaks Volumes

In the corner of a dimly lit computer room at Actuality Systems Inc. stands a transparent globe with a diameter of about 20 in. - the world's highest-resolution 3-D, volumetric display.

Peering into this high-tech crystal ball, I see what looks like a thin green ribbon twisting around itself. At two places where there are "pockets" in the ribbon's structure sits a white blobby mass with several appendages that fit neatly into the pockets. I can walk around the globe and look in from the top to see what had been obscured from a different angle.

Gregg Favalora, founder and chief technical officer of the Reading, Mass.-based firm, tells me the green ribbon is a representation of the structure of the human immunodeficiency virus (HIV); the white object represents a chemical molecule designed specifically to fit the virus' complex shape.

No other type of display can show so completely how the molecule "docks" with the virus. That's when it hit me that 3-D visualization can significantly expand one's understanding of a virtual object.

What's important here is that this is a real 3-D image, not a stereoscopic picture made from two single still images and representing a single viewing point. Here, I can see the 3-D shape of the image directly from all sides. In other words, I can see it as a volume in space, which is why this is called a volumetric display. And since much of today's research into new drugs revolves around structural issues such as designing molecules to interact with specific pathogens, visualization such as the Actuality display represents a real shortcut. Looking at a 2-D representation of the same image, I was struck by how little I could see clearly, particularly spatial relationships.

How It Works

A few other volumetric displays are on the market but none with the resolution of Actuality's. The quality, or resolution, of a volumetric image is measured in a unit called the voxel, or volume pixel. The Actuality display has a resolution of 768 by 768 pixels by 198 planes by eight colors, for a total of 116 million voxels.

By comparison, the few other volumetric displays I've seen referenced typically have only about 12 planes, a severe limitation when it comes to showing detail.

The technology behind the display is surprisingly simple. Most other attempts at creating a volumetric display involve multiple lasers and complex, often helical, semitransparent screens.

Inside that transparent sphere, Actuality uses simple LCD projection and a white plastic disc, approximately 10 in. in diameter, which rotates at about 700 rpm. On one side in the base is a three-LCD projector that uses a normal projector-type lamp. It flashes a constantly changing image either directly onto the disc or onto a facing mirror that spins with the disk.