Software uses sculptor's touch on virtual objects

PORTLAND, Ore. — Virtual reality software has long held the promise of enabling designers to sculpt the sleek curves and contours of a new product from "virtual clay," but until recently designers had to learn a whole new procedure for working with computer-aided design (CAD).

Until now, virtual shapes could only be sculpted via keyboard and mouse input to define "splines" or similar mathematical objects that determine a curve's shape, but have nothing to do with sculpting. More recently, haptic feedback devices have arrived that offer a more direct relationship between the hand and a virtual object, but they still lack the naturalness of hand-shaped clay.

A project of the State University of New York at Buffalo is seeking a direct intuitive method for working with virtual shapes in a CAD system using the type of glove developed in virtual reality systems. Using the approach, it is possible to work with actual clay to sculpt a shape, which is then automatically transferred to a CAD representation.

"Ours is the only technology capable of transferring touch directly from the user's hand to the virtual object," said associate professor Thenkurussi Kesavadas, director of the Virtual Reality Lab.

Today many designers still use real clay — as is done in Detroit for new car designs — the surfaces of which are then scanned and converted into a three-dimensional file for a CAD program. Then the designer has to switch to being a computer operator to refine and finalize the design using b-spline surfaces. Unfortunately, the two skill sets-sculpting and computer operation-have almost zero overlap, so designers must learn both skills.

Some products have appeared recently that use input devices such as a pencil-like stylus to modify virtual CAD shapes. For example, Reachin Technology AB (Stockholm, Sweden) markets a system using stereo displays and a haptic stylus that gives the user the illusion that a virtual object can be touched and modified just as though it were a physical object on the desktop.

Kesavadas' ModelGlove, however, enables a designer to sculpt virtual clay using exactly the same hand motions and sculpting skills used with real clay. In fact, a real piece of clay is a part of the setup. A designer puts a block of real clay in front of the computer, puts on the glove and starts sculpting the clay. The on-screen virtual block responds via the ModelGlove, which records the force exerted by the hand when depressing and shaping the real block of clay. The glove communicates the motions to the computer model.

"Ours is a 3-D input device. You move your hand freely and when you grab objects in the real world with the glove, on the screen you see the object deform," said Kesavadas. "You can put this in the hands of a designer who has never used a CAD package, and they immediately begin creating beautiful smooth contours with no training whatsoever." Kesavadas developed the tool with Ameya Kamerkar, a graduate student in the Department of Mechanical and Aerospace Engineering. Kesavadas has applied for a patent through the university's Office of Science Technology Transfer and Economic Outreach.

Unlike other VR approaches, here the real clay provides the force feedback, rather than requiring an expensive and elaborate haptic-output mechanism from the computer that merely simulates the feeling of clay. Instead, the user watches the screen to see how the virtual clay is "shaping up," all the while pushing on the real clay. The real clay does not take on the contours of the object being sculpted. Instead, the designer merely employs the clay to provide a realistic feeling.

"Ours is just an input device only. You feel the real clay deforming, but the computer doesn't give you any feedback-it's the natural object" you're touching, said Kesavadas.

Currently, Kesavadas' ModelGlove only has a single point of contact with virtual objects-only one finger is wired-but Kesavadas predicts that even a commercial version with all fingers wired could eventually retail for as little as $500.

Other improvements under way include a palette of virtual tools, such as for cutting clay, from which users can select while they sculpt. Kesavadas' team is also writing translation software that will allow designers to use the glove as a front end for commercial CAD packages.

"We are also planning to make it wireless," said Kesavadas.

The University at Buffalo licenses its VR Lab inventions to Tactus Technologies Inc. (Amherst, N.Y.), which offers commercial versions of Kesavadas' previous inventions. One of those is the TacTell Glove, which uses force and position sensors to permit medical professionals to perform palpation while automatically extracting the physical properties of tissue for a computer file. Likewise, Tactus Technologies' V-Surgeon enables students to practice surgery in VR.