Mitsubishi soups up graphics board to bring 3-D volume rendering to PCs

June 9, 1999

VolumePro 500 renders at 30 frames per second For a medical imaging industry concerned about the bottom line, finding a way to conduct complex 3-D volume rendering tasks without a pricey workstation would be a boon. Technology firm Mitsubishi

VolumePro 500 renders at 30 frames per second

For a medical imaging industry concerned about the bottom line, finding a way to conduct complex 3-D volume rendering tasks without a pricey workstation would be a boon. Technology firm Mitsubishi Electronics America may have found a solution with a new 3-D graphics accelerator board that the company launched last month. Mitsubishi plans to sell the board to medical imaging OEMs, software developers, and other companies that would like to market software capable of conducting 3-D volume rendering on conventional PCs.

The widespread use of 3-D rendering for medical imaging applications has proceeded in fits and starts. While standard PCs can handle simpler applications like surface rendering, expensive workstations are usually required for more complex tasks like volume rendering. Mitsubishi hopes its new VolumePro 500 PCI accelerator board will bring 3-D to the masses by enabling PCs to conduct complex volume rendering tasks at real-time frame rates of 30 fps.

Mitsubishi licensed the basic technology behind VolumePro in 1996 from researchers at the State University of New York at Stonybrook. After it purchased rights to the SUNY patent, the company established a small work group at its Cambridge, MA, office, which in 1997 became its Real Time Visualization (RT Viz) division. Mitsubishi has developed 35 patents of its own from the original SUNY patent.

The SUNY researchers had developed an algorithm called ray casting, which shoots rays of light through a volume object from a base plane and produces a composite image. Although the ray-casting algorithm isn’t new—SUNY has been developing the algorithm for almost 20 years—until now the computer industry hasn’t been able to take advantage of it because of the difficulty of putting large amounts of data on silicon chips cheaply. With the industry’s development of denser, less expensive silicon chips, the possibility of doing volume rendering on PCs is becoming a reality.

“Based on those original (SUNY) patents, we’ve pioneered the field of commercially viable volume rendering,” said Steve Sandy, Mitsubishi’s director of business development. “This is the world’s first chip in a volume-rendering engine that allows people to do real-time frame rates on PCs.”

VolumePro is hitting the market at a good time. Such new technologies as multislice CT scanners are producing more and more data, making it more difficult for radiologists to interpret scans on a 2-D slice-by-slice basis. Three-dimensional volume rendering can make it easier for both radiologists and referring physicians to visualize anatomy.

“This is going to help radiologists,” Sandy said. “Because the amount of data and the resolution of data is becoming more complex, it’s getting more difficult for radiologists to interpret slice by slice.”

Voxels versus polygons.
Mitsubishi’s algorithm differs from many other 3-D rendering techniques in that it handles image data as voxel cubes rather than polygons. Traditionally, 3-D objects have been rendered polygonally by placing a grid over the object and filling the image in a technique called texture mapping. Polygons are excellent for rendering surfaces, but they can’t image internal structures well, Sandy said. Since volume data created by scans such as those produced with MRI is already rendered volumetrically, using voxels rather than polygons is more effective, Sandy said.

Mitsubishi calls its version of the SUNY algorithm object order ray-casting, because VolumePro collects data slice-by-slice and row-by-row, hitting each voxel in an object as it reads each slice. The board has 128 MB of memory, enough to store 512 x 512 x 256 volume slices, and can render a 256-cubed data set at 30 frames per second. VolumePro can be used with Windows NT or Unix platforms.

Although Mitsubishi is not the only firm trying to bring 3-D to PCs, the company doesn’t see any competition between VolumePro and products from 3-D software developers like Voxar of Scotland and Vital Images of Minneapolis. In fact, Vital Images intends to exhibit in the Mitsubishi booth at the Special Interest Group on Computer Graphics (SIGGRAPH) conference planned for August in Los Angeles. The meeting will mark Mitsubishi’s formal introduction of VolumePro, and the company will follow up with a booth at this year’s RSNA meeting.

Voxar in 1997 introduced a library of 3-D software development tools that it claimed would allow PCs to perform high-end 3-D applications like volume rendering (SCAN 2/18/98). But software isn’t enough, according to Mitsubishi: What’s needed is a graphics board like VolumePro that can efficiently handle the massive amounts of data produced by scanners.

Mitsubishi plans to price VolumePro at approximately $3000 for the board alone, and $5500 for the board with the software development kit that is available for application developers and system integrators. RT Viz has begun shipping the boards to early developers, and expects to be in full production in July.

© 1999 Miller Freeman, Inc.All rights reserved.