"Walkthru Project" Renders Real-Time 3D Models For Engineering And Architecture

The WalkThru Project, led by UNC computer science professors Fred Brooks and Dinesh Manocha, is funded by the National Science Foundation (NSF) Division of Advanced Computational Infrastructure and Research. The UNC team develops new algorithms and software for advanced prototyping that could yield safer yet more cost-efficient buildings and vessels.

"The overall goal is to create interactive computer graphics systems that let a viewer experience complex 3D spatial models by simulating walk-throughs of the actual facility," said Brooks, who started the project in the mid-1980s.

The computer scientists take very large CAD/CAM (computer-assisted design and manufacture) models and render them as fully navigable 3D environments, including a tanker with 82-million separate elements and a 13-million-element electric power station. Until now, such complex virtual structures yielded slow, jerky graphics that did not permit real-time navigation and manipulation.

Cosmetically, the WalkThru tanker simulation looks coarser than what movie-goers have come to expect since Titanic. But it has a level of technical realism that more than equals anything Hollywood has done. Its 3D space is completely navigable from stem to stern, consisting of 82 million triangles.

Synthetic environments that succeed in providing a realistic experience for their users can also be used for collaboration between far-flung design teams. This helps limit travel time and costs, as an engineer in the U.S. can talk by speaker phone with a colleague overseas, while they both walk through the same 3D environment.

"One of the challenges," Manocha said, "is to develop a scalable system to achieve real-time walkthroughs of very large CAD/CAM models with high-accuracy rendering of spatial arrangements. We write efficient algorithms to accelerate rendering and improve collision detection, as when the user 'bumps' into a stationary structure."

CAD/CAM and architectural models may contain millions of small 3D elements, called "primitives." To display these models at interactive rates, developers must write algorithms to reduce the number of primitives that the graphics system is required to render. The team is also developing algorithms to assign processor priority according to each element's visibility, which permits users to see and interact with the model at a greater level of detail.

Although WalkThru Project models were developed on advanced graphical workstations made by Silicon Graphics, Inc., they will also run on high-end PCs. The walkthroughs can also be viewed in immersive virtual reality caverns that let the user experience the simulations on a life-size scale.

In 2000, Brooks received the Turing award -- the highest honor in computer science -- from the Association for Computing Machinery. Manocha was a 1995 recipient of the NSF CAREER award for promising young faculty. Other team members include UNC computer science faculty Anselmo Lastra (rendering acceleration algorithms) and Ming Lin (collision detection and proximity simulation).

"Over the years, this project has depended on excellent graduate students who have gone on to work at places such as Lucent Bell Labs, Johns Hopkins University, the University of Virginia and other top institutions," Brooks said. "Our faculty have paid close attention to the educational aspect."

The team's simulation and 3D model of a coal-fired power plant are available for non-commercial public use. Collaborative partners of the WalkThru Project include General Dynamics, Newport News Shipbuilding and the NASA Jet Propulsion Laboratory. In addition to NSF, other federal sponsors have included the National Institutes of Health, the U.S. Army and Navy, the Defense Advanced Research Projects Agency and the U.S. Department of Energy.

For more about the WalkThru Project, see: http://www.cs.unc.edu/~walk

For 3D animations, see: http://www.cs.unc.edu/~geom/rendering/videos.shtml