Modeling and animating skin with wrinkles is very important for character animation in films and games. To model wrinkles, it is important to consider all aspects that influence the formation of wrinkles such as skin texture and physiology, mathematics of elasticity, geometry and the associated physics behind the wrinkling phenomenon, and integrate these techniques efficiently. A number of previous approaches, including physically-based modeling, geometric wrinkling, texture or bump mapping, have tried to model skin with wrinkles; however, realistic and computationally efficient modeling of skin with wrinkles remain a challenge.;In this dissertation, we propose an integrated physiology and physically-based geometric model of skin that allows dynamic formation of wrinkles suitable for animation. The physics of wrinkling involves the study of large deformations of naturally thin elastic sheets and is governed by a set of nonlinear partial differential equations that are very difficult to solve. Instead, we model the wrinkling of skin as curvature-driven evolution of one-dimensional profile curves (sampled from the skin mesh through intersections with a cutting plane) that allows for singularities. Skin elasticity is captured using an energy functional defined by skin stretching, bending, interacting with underlying components, and constrained by self-collisions. The proposed solution determines skin motion by seeking its minimal energy configuration; fast convergence of the numerical solution is ensured through a good initial estimate formulated using careful placement of joint vertices.;The regularity of skin deformation allows us to dynamically reconstruct the 2D skin mesh from the 1D profile curve animations. This two-step approach is computationally lightweight. Our energy minimization solutions converge in quick time without the use of any special purpose hardware. Our model sizes are compact and storage-efficient since the wrinkles are generated on-the-fly through a parameterized subdivision of the wrinkles triangles during animation. These parameterizations are intuitive and allow the animator to control the width and depth of the wrinkles as well as the height of the folds surrounding the wrinkles. Our approach allows realistic skin animation by supporting automatic generation of wrinkles and smooth motion of skin joints.;We have implemented the proposed modeling and animation system for skin with dynamic wrinkling in C++ which allows a user to control the parametrizations, extract profile curves, identify the anchors, and define association between profile curve and skin mesh vertices automatically. We have applied our system to animate skin on the human finger with wrinkles.
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