Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

High-tech hairdo: New Cornell method gets that natural look in computer-generated blond hair

21.07.2006
Poets and novelists often describe hair as "shining" or "shimmering." Dark hair has a "sheen"; blond hair "glows." All this comes about because of the complex scattering of incident light off of individual hairs and from one hair to another.

Reproducing this effect in computer graphics has always been a challenge. Computers can create three-dimensional structures resembling hair, but the process of "rendering," in which the computer figures out how light will be reflected from those structures to create an image, requires complex calculations that take into account the scattering between hairs. Current methods use approximations that work well for dark hair and passably for brown, but computer-generated blondes still don't look like they're having more fun.


Marschner lab/Cornell University

On the left, a computer-generated image of blond hair with only direct illumination. At right, the same image rendered with the new algorithm that takes into account the multiple scattering of light through the hair. Direct illumination catches the highlights but fails to show the true color. Copyright © Cornell University

But now Cornell researchers have developed a new and much quicker method for rendering hair that promises to make blond (and other light-colored) hair more realistic.

Steve Marschner, Cornell assistant professor of computer science, developed the new method with Cornell graduate student Jonathan Moon, who will present the work at the 2006 SIGGRAPH computer graphics conference in Boston July 30 to Aug. 3.

"The model that's been around since the '80s works for black hair, and a model we introduced in 2003 in collaboration with workers at Stanford gets brown hair right and makes blond hair better," said Marschner, an award-winning computer graphics expert who specializes in making computer graphics more realistic, particularly in animating human beings. "Using that model with our new work provides the first practical method to use physically realistic rendering for blond hair and still get the right color."

The problem is that light traveling through a mass of blond hair is not only reflected off the surfaces of the hairs, but passes through the hairs and emerges in a diffused form, from there to be reflected and transmitted some more.

The only method that can render this perfectly is "path-tracing," in which the computer works backward from each pixel of the image, calculating the path of each ray of light back to the original light source. Since this require hours of calculations, computer artists resort to approximations.

"People do something reasonable for one bounce and then assume it reflects diffusely," Marschner explained. In other words, he said, they assume that hair is opaque. "In light-colored hair it's important to keep track of the hair-to-hair scattering," he said.

Marschner and Moon's algorithm begins by tracing rays from the light source into the hair, using some approximations of the scattering and producing a map of where photons of light can be found throughout the volume of hair. Then it traces a ray from each pixel of the image to a point in the hair and looks at the map to decide how much light should be available there.

The result, in a test rendering of a swatch of blond hair, appears almost identical to a rendering by the laborious path-tracing method. Path tracing for the test required 60 hours of computation, while the new method took only 2.5 hours, the researchers report.

Marschner now plans to look for better ways to generate the geometric model of hair that underlies the rendering and to simulate realistically the way hair moves. "Tools that generate hair generate random strands in space, and it's unclear whether the arrangement is realistic," he explained.

Marschner shared a technical achievement award from the Academy of Motion Picture Arts and Sciences in 2004 for a method of rendering translucent materials, including human skin, which helped to make the character of Gollum in the "Lord of the Rings" films more realistic. His earlier methods for rendering hair helped to create computer-animated versions of Naomi Watts in the arms of the computer-animated gorilla in the 2005 version of "King Kong."

Blaine Friedlander | EurekAlert!
Further information:
http://www.cornell.edu

More articles from Information Technology:

nachricht NASA CubeSat to test miniaturized weather satellite technology
10.11.2017 | NASA/Goddard Space Flight Center

nachricht New approach uses light instead of robots to assemble electronic components
08.11.2017 | The Optical Society

All articles from Information Technology >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

NASA detects solar flare pulses at Sun and Earth

17.11.2017 | Physics and Astronomy

NIST scientists discover how to switch liver cancer cell growth from 2-D to 3-D structures

17.11.2017 | Health and Medicine

The importance of biodiversity in forests could increase due to climate change

17.11.2017 | Studies and Analyses

VideoLinks
B2B-VideoLinks
More VideoLinks >>>