Scottish software firm Voxar develops high-end 3-D for PCs

Company claims library provides speed edge

A Scottish software company called Voxar has developed a library of 3-D software development tools that it claims will enable off-the-shelf PCs to perform high-end 3-D applications like volume rendering. The Edinburgh company hopes to rewrite the rules of 3-D image rendering, a technology that for the most part has been limited to high-powered workstations capable of the processing speeds necessary to handle large 3-D data sets.

Voxar made its debut at December's Radiological Society of North America meeting, where its demonstration of volume rendering on off-the-shelf Intel Pentium PCs impressed attendees in the infoRad section of the conference. Voxar's development package is called Voxarlib Medical, which consists of C++ code that medical imaging vendors can use to write 3-D applications to be sold directly to end users or incorporated into other products, such as PACS software.

Voxarlib Medical's basic configuration began shipping in June and supports 3-D techniques such as surface rendering, maximum intensity projection (MIP), and multiplanar resampling (MPR). The company is developing a version that supports more sophisticated volume-rendering techniques and should have that software in beta testing later this year.

How fast is Voxarlib Medical? On applications running on a standard PC with a 200-MHz Pentium MMX processor, users can rotate a full-volume 20-MB CT scan of 512 x 512 x 40 slices at dozens of frames per second. When users stop the rotation to zoom in on a selected area, the image gains full resolution in less than a third of a second. The result is interactive 3-D on a PC or Macintosh at a fraction of the cost of workstation-based systems, according to the company.

The speed of Voxarlib's applications comes from the library's treatment of 3-D objects as voxels, or cubes, rather than as polygons, as most other 3-D software programs handle objects. A CT, MRI, or ultrasound scan reproduces patient anatomy as thousands of voxels that fit together to form an image. Therefore, rendering the scan in 3-D using voxels is a more faithful representation of the original data than polygons, according to Euan Mackenzie, commercial director for the company. Software developers have resorted to polygons to display 3-D images because of the difficulty in rendering voxel-based images quickly, he said.

Voxar was founded in 1991 by Andrew Bissell, a computer science graduate from Edinburgh University. In its early days, the company considered entering the market for custom 3-D graphics hardware, but decided that such a direction would be difficult due to the massive amounts of capital that would be required to keep its hardware a step ahead of Intel's. Instead, Voxar decided to take advantage of Intel's engineering muscle by developing 3-D software that would run faster with each new generation of processing chip. Voxar also sells versions of Voxarlib to the oil exploration and entertainment industries.

In addition to offering development tools to OEMs, Voxar is developing a complete 3-D rendering package based on Voxarlib Medical that OEMs can market under their labels without having to do their own software development work. Apart from the research market, however, Voxar does not plan to sell its product directly to clinicians.

"I don't think that's where our core skill set is," Bissell said. "We have OEMs who have that core skill set, and they can add a great deal of value through what they know about the end-customer markets."

Voxarlib Medical runs on Windows 95 and NT, Macintosh, and Unix platforms. A Voxarlib Medical surface-rendering package costs $5000 for a Windows or Mac version and $7500 for a Unix version, while a Voxarlib Medical volume-rendering package will cost $15,000 for a Windows or Mac version and $22,500 for a Unix version. OEMs also pay licensing fees based on applications they develop using Voxarlib Medical.