To be clear, the project did not focus on deforming the 3D model into precisely the same pose as the cartoon’s. “When I showed that the motion of some classic 2D cartoon animations, such as the famous Goofy, was transferred to arbitrary complex 3D objects, such as the Stanford armadillo, with 170,000 vertices, in a few minutes,” Zhou recalls, “my boss and colleagues were just shocked.” It’s a classic example of computer-generated “life” imitating art, particularly so when you consider that Zhou and his collaborators got permission to use and reproduce some famous animation cels from Disney Feature Animation. All these movements come from tracing a few curves from a cartoon image and transferring them to a mesh model. Not much later in the video, the same dinosaur is dancing. Such techniques can be applied any number of ways. Those curves are applied to the dinosaur mesh, and voilà, the dinosaur begins to kick, in a fashion nearly identical to that of the animated feline. Then a spinal curve and a leg curve are copied from a frame of a cartoon cat in the midst of an energetic kick. The model is rotated to define the projection plane for each control curve. Control curves are drawn along the spine and the legs of a 3D dinosaur skeleton. Our algorithm will automatically transfer the 2D cartoon deformations to the 3D object.”Ī video makes the advances abundantly clear. The user specifies one or more 3D control curves on the object, and for each curve, a series of 2D curves in the cartoon image. “To use our system,” he says, “the user simply takes a 3D object and a 2D cartoon image sequence. “We realized,” Zhou says, “that previous surface-detail preservation is not enough for such large deformations.”īy analyzing the direction of a limited set of points within the surface framework of the mesh, Zhou was able to produce dramatically superior 3D movements. But that required providing a mesh framework for the entire interior of a model, a notoriously difficult undertaking. Techniques, such as Poisson mesh editing, the previous method employed by Zhou and associates, resulted in unnatural folds when an item-say, a leg-was bent, and an unrealistic loss of volume when an item was twisted.Įarlier techniques relied on manipulating surfaces to produce realistic movements. Mathematically, it is computed as the difference between the point and the weighted average of its neighboring points.ĭetermining how the 3D mesh model reacts to various movements is a key to creating lifelike movements. “The volumetric graph Laplacian of a point in a three-dimensional space,” Zhou states, “is defined as the relative position with respect to its neighboring points. Volumetric graph Laplacian, it appears, is a superior technique. Previous deformation techniques often produce implausible results with unnatural volume changes and self-intersections. “The goal of our work,” Zhou says, “is to develop an interactive system to transfer the deformations of 2D cartoon characters to 3D objects. Nonrigid, highly exaggerated movements? Sounds like Bart Simpson skateboarding through Springfield. But there has been a lingering challenge with large deformations, such as those found with characters performing nonrigid, highly exaggerated movements. Many applications have been devised to help artists construct stylized body shapes and body movements. Mesh deformation has been a valuable technique in cartoon modeling and animation. The biggest challenge is how to balance these two objectives.” The other part is automatic, real-time performance. “One part of this research goal is realism, which takes a lot of manual work and computation time. “We are inventing technologies to generate beautiful and realistic pictures in real time for the film and gaming industries. “My research interests focus mainly on computer-graphics algorithms,” Zhou explains. In layman’s terms, that means making the movements of three-dimensional animations appear more real and lifelike. “We present a novel technique for large deformations on 3D meshes,” Zhou says. describe the use of a technique called volumetric graph Laplacian to diminish unrealistic effects of 3D modeling present in previous work in this field. Zhou’s Web site reveals an impressive list of publications and projects related to that field, among them a paper presented during SIGGRAPH 2005 entitled Large Mesh Deformation Using the Volumetric Graph Laplacian, co-written by former Microsoft Research Asia intern Jin Huang, John Snyder of Microsoft Research’s Redmond lab, fellow Asia-lab researcher Xinguo Liu, Hujun Bao of Zhejiang University, and Baining Guo and Harry Shum of Microsoft Research Asia.
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