Modeling of internal friction adds new wrinkle to realistic simulation of cloth behavior

(Press-News.org) Contact information: Jennifer Liu
jennifer.c.liu@disney.com
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Disney Research
Modeling of internal friction adds new wrinkle to realistic simulation of cloth behavior Disney Researchers lead international collaboration Most people try to keep clothing wrinkle free, but computer graphic artists, striving for realism in computer simulations, take pains to be sure clothing wrinkles, folds and stretches naturally. A new computer modeling technique developed by Disney researchers and academic collaborators addresses this problem.

The new modeling technique seeks to replicate cloth's tendency to preferentially develop wrinkles and folds in areas where they have previously occurred. The researchers accomplished this by incorporating models for internal friction – the resistance of a material to bending, stretching and compression.

"Many researchers have identified internal friction as a source of this effect, but until now no one had incorporated it into computer animation models of cloth," said Rasmus Tamstorf, senior research scientist at Walt Disney Animation Studios.

Plasticity models, which account for permanent changes in shape when force is applied, are another way to simulate these persistent folds and wrinkles, noted Derek Bradley, associate research scientist at Disney Research, Zürich. But plasticity models work best only when large forces are at play. By contrast, the internal friction models responded to even modest loads and proved more suitable for "locally persistent wrinkles."

Tamstorf and fellow researchers from Disney Research, Zürich, Cornell University, MIT and URJC Madrid adapted a widely used general model for internal friction with good results. They will report their findings at the SIGGRAPH Asia 2013 conference, November 19-22, in Hong Kong.

In addition to improving the modeling of persistent or preferred wrinkles and folds, internal friction results in more realistic stretching and rebounding of cloth. Because it resists motion, internal friction also can help simulated wrinkles settle in one place faster once a character's motion stops, said Eder Miguel, a Ph.D. student in the Modeling and Virtual Reality Group at URJC Madrid.

### Along with Tamstorf, Bradley and Miguel, research team members included Bernhard Thomaszewski and Bernd Bickel of Disney Research, Zürich, Wojciech Matusik of MIT, Steve Marschner of Cornell and Miguel A. Otaduy and Sara C. Schvartzman of Rey Juan Carlos University (URJC) Madrid.

This research was supported in part by the European Research Council and the Spanish Ministry of Economy. For more information, and a video, please visit the project website http://www.disneyresearch.com/project/internal-friction-in-cloth/ About Disney Research Disney Research is a network of research laboratories supporting The Walt Disney Company. Its purpose is to pursue scientific and technological innovation to advance the company's broad media and entertainment efforts. Disney Research is managed by an internal Disney Research Council co-chaired by Disney-Pixar's Ed Catmull and Walt Disney Imagineering's Bruce Vaughn, and including the Directors of the individual labs. It has facilities in Los Angeles, San Francisco, Pittsburgh, Boston and Zürich. Research topics include computer graphics, video processing, computer vision, robotics, radio and antennas, wireless communications, human-computer interaction, displays, data mining, machine learning and behavioral sciences.