Computer images: hanging in space.

Computer images: Hanging in space

Projected into space, the green, three-dimensional image of a miniature Chevrolet Camaro floats in the air. Although the 9-by-4-inch image is somewhat grainy, anyviewer can pick out the car's tiny front and rear license plates. Unveiled this week at the Massachusetts Institute of Technology, this hologram is the first to be generated from pictures produced on a computer.

Two key developments led to this initial step in creting a new type of computer display, says MIT's Stephen A. Benton, the principal investigator. "We came up with a new way of making holograms to produce this kind of suspended image from computer data," he says. "And this has been paralleled by research in computer graphics, in which the image is processed in such a way as to give a realistic, undistorted, three-dimensional image."

The researchers start with enough digital data describing an object, such as a car, to build up a detailed picture on a video screen. A computer then processes the data to generate images of the car as seen from about 1,000 different angles, covering the front and back and one side. Each view is carefully photographed on 35-millimeter film. Then, with laser light, all of these views are projected at the proper angles onto a single sheet of film to produce the hologram.

Laser light passing through the completed hologram generates the final three-dimensional image. Although a viewer can't walk all the way around the image to see all sides of the object, it's still possible to get a good sense of what the solid object would look like.

This technique, the researchers say, may someday be useful for designing buildings or products. In the case of cars, computer-generated holograms may eliminate the need to carve clay models of proposed designs. Doctors and medical researchers may also find such displays useful, for example, for examining body parts before surgery.

Benton and his group are working on creating full-color and larger images (as of now, images can be projected only in the color of the laser light). They are alos trying to speed up the process for converting a set of computer images into a hologram, which now takes up to a week to accomplish.

This is just the very first attempt at putting all the principles into play, says Timothy P. Browne, associate director of MIT's new Media Laboratory, where the imaging research is taking place. "It's like photography in the 1860s," he says. "There's nothing particularly clear and sharp about it, but you can see that it works."