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UBC Theses and Dissertations

Biomechanical simulation of the hand musculoskeletal system and skin Li, Duo


This thesis presents a biomechanically based hand simulator. We make contributions at two di erent levels: hand motion and hand appearance. We rst develop a musculotendon simulator, and apply this simulator to an anatomically based hand model. Anatomically based hand simulation is challenging because the tendon network of the hand is complicated and it is highly constrained by the skeleton of the hand. Our simulator employs the elegance of the Eulerian-Lagrangian strand algorithm, and introduces a 2D planar collision approach to e ciently eliminate unnecessary degrees of freedom and constraints. We show that with our method, we obtain the coupling between joints automatically, and achieve the storage of energy in tendons for fast movements. Also, by injuring a tendon, we are able to obtain simulations of common nger deformities. Although the musculotendon based hand simulation produces natural hand motion, hand animation is usually observed at the skin level. We present a novel approach to simulate thin hyperelastic skin. Real human skin is a thin tissue which can stretch and slide over underlying body structures such as muscles, bones, and tendons, revealing rich details of a moving character. Simulating such skin is challenging because it is in close contact with the body and shares its geometry. We propose a novel Eulerian representation of skin that avoids all the di culties of constraining the skin to lie on the body surface by working directly on the surface itself. Skin is modeled as a 2D hyperelastic membrane with arbitrary topology, which makes it easy to cover an entire character or object. We use triangular meshes to model body and skin geometry. The method is easy to implement, and can use low resolution meshes to animate high resolution details stored in texture-like maps. Skin movement is driven by the animation of body shape prescribed by an artist or by another simulation, and so it can be easily added as a post-processing stage to an existing animation pipeline. We demonstrate realistic animations of the skin on the hand using this approach. We also extend it to simulate other parts of human and animal skin, and skin-tight clothes.

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Attribution-NonCommercial-NoDerivatives 4.0 International