Imaging in the Round

Brent D. Johnson

One of the biggest bottlenecks in designing new products is in communicating work in progress -- which usually requires multiple physical prototypes -- to other engineers and managers. Although three-dimensional displays have found application in prototyping for industries such as pharmaceuticals, architecture and automotive design, the typical stereoscopic headwear that is associated with these devices has been known to cause users nausea and discomfort and to make collaboration among designers difficult.

At right, DNA rendered with Accelrys' WebLab ViewerPro illustrates the Helios device's use for molecular visualization, pharmaceutical design and rapid visual inspection of protein structure libraries.

The new Helios volumetric 3-D display from Actuality Systems Inc. allows engineers to view 3-D images from any angle without goggles. This means that they can experiment with more design iterations without committing resources to a physical prototype. The device delivers 100 million voxels, whereas most displays don't exceed 5- to 10-million voxel resolution, according to the company's founder, Gregg Favalora.

The instrument processes digital 3-D data into approximately 200 vertical slices, arranged around a centerline like apple slices around a core. It projects these digital slices onto a diffuser rotating 20 times a second. Persistence of vision fuses the segmented images together into a 3-D image.

The 3-D display can be used for military visualization and navigation and for aeronautical and astronautical imaging.

Favalora, who had developed 3-D raster-scan displays as a university student, followed a new approach for the Helios device. While some aspects of the design have been around since the late 1950s, adapting the technology to modern components was the most challenging part of building the device. For example, the designers had to invent a group of fast graphic algorithms that were optimized for the unusual coordinate space employed by the display.

"The heart of the system," said Favalora, "is a very fast projector based on Digital Light Processing from Texas Instruments." This technology was crucial because of its image quality and frame rate. The projector rapidly converts digital content into a bit stream that is read by a device with more than 750,000 microscopic mirrors that construct the image. Because the 3-D imagery is constructed of 200 2-D planes, which are projected 24 times per second, it requires a projector such as this that can be driven at approximately 4000 images per second. "That gives us the ability to offer customers a display that is completely bit-mapped," said Favalora.