Computer Graphics World

Projection ■ ■ ■ ■ 20 vehicles, nine sedan chairs, and 170 trees. Th e painting is famous because of its geometrically accurate images of the boats, bridges, shops, and scenery using a bird's-eye view. The Quilting Process Th e process of converting the scroll into a dynamic digital version was an arduous task. Since this painting is considered to be China's Mona Lisa, Crystal CG was allowed, only under intense security, to borrow the original scroll from the Palace Museum in the Forbidden City and keep it for three months with the purpose of scanning every inch of it. After scanning the entire scroll, each of the hundreds of human and animal characters had to be digitally removed. All the elements of the scroll—from the buildings, pavilions, terraces, rivers, fi elds, and trees— were separated into individual elements so that each could be textured and animated separately. Using Autodesk's 3ds Max and Adobe's After Eff ects and Photo- shop running on 40 PC workstations, the artists re-created the vari- ous elements, adding subtle animated details—for instance, trees and crops gently sway in the wind, while river currents easily fl ow. As each element was completed, it was composited back into the scroll in its original location by the art team, starting fi rst with the background ele- ments, such as buildings, terraces, rivers, and trees. Th en, the animated details were added. One special eff ect the team added to the digital tapestry that was not present in the original painting (set during daylight hours) is the transi- tion to a nighttime scene every four minutes—alternating two minutes for the day view and two minutes for the night view. Slowly, the scene changes from day to dusk to night, the only hint that time is shifting is the lighting of hundreds of tiny lanterns, some carried by the 377 animated characters, and others attached to trees and shops. In order for the depiction to be historically accurate, 10 diff erent kinds of lanterns were used in the nighttime scene—just one of the many attentions to detail the Crystal CG team included in the work. "Historical records show that during this period in China's history, lanterns of various sizes and shapes were used according to where they were hung—be it the gates of homes, government offi ces, stores, or other locales," Yu Zheng notes. Still, Crystal CG went to great lengths to stay true to the original work, and more than 60 percent of the fi rm's display is identical to the original artwork. After the background elements were completed, the artists set their focus on the hundreds of characters they had to hand-animate and re- insert into the image. Each character was designed and animated in 3D, then textured and colored, before being converted back into 2D for compositing into the scene. All the animation was keyframed within 3ds Max, taking anywhere from three hours to two days to complete per character, based on the character's importance in the picture. And, herein lies one of the main hurdles the artists had to overcome: that of the traditional Chinese perspective of painting. Because the original artwork used a bird's-eye view of the scene, each character had to be animated and the perspective correctly matched to fi t the scene. "Traditional Western paintings and mainstream 3D video production software, like 3ds Max, are based on the principle of 'perspective,' namely the relatively rigorous principle of descriptive geometry, while traditional Chinese paintings emphasize 'cava- lier perspective,' which is best exemplifi ed in the long scroll-like Riverside Scene at the Qingming Festival," explains Yu Zheng. "With careful observation and analysis, we may Using 3D tools and techniques, Crystal CG re-created the scenes from a famous ancient Chinese painting in painstaking detail (shown in the images at left). At top is a picture of the digital re-creation, which spanned the length of a pavilion that housed the project at the Shanghai Expo. October/November 2011 47

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