Accurate and Efficient Visual Simulation of Fiber-based Mechanical Structures

基于纤维的机械结构的精确和有效的视觉模拟计算机图形学模拟中许多最困难的挑战涉及由纤维组成的材料。在外观很重要的应用中，从设计纺织品和服装到渲染虚拟演员再到制定头发化妆品，了解这些材料的物理特性如何影响它们的运动和外观是至关重要的。基于纤维的结构与其他材料的表现不同。由于纱线可以弯曲和滑动成不同的宏观形状，因此针织物比其组成纱线具有更大的延伸性。一头长发自由而流畅地移动，形成和打破数百万根头发的接触，产生部分平滑，部分不连续的整体运动。本研究旨在通过从根本上改变底层物理和计算模型来提高布料和头发模拟的准确性。该项目遵循测量、建模、仿真和验证的方法。基于图像的测量用于捕获完整的织物变形。利用这些数据和纱线级纺织力学的文献，建立了基于织物实际物理特性的本构模型，并使用通常不用于纺织品模拟的先进数值方法对其进行了模拟。这些结果正在根据实验室数据和服装设计中的实际问题进行评估。通过将现代图形和仿真工具与纺织力学的详细模型在严格的验证过程中结合在一起，该项目为未来的计算机图形布料仿真奠定了坚实的科学基础。为纤维-纤维相互作用设计的计算方法也被扩展到有效的头发线级模拟。在模拟得到验证后，该项目将检查近似和算法，以实现有效的模拟。最终的结果将是新的、基于物理的模型，用于布料和头发的力学，适合于视觉应用。

Accurate and Efficient Visual Simulation of Fiber-based Mechanical StructuresSteve Marschner, Cornell UniversityMany of the most difficult challenges in simulation for computer graphics involve materials composed of fibers. In applications where appearance matters, from designing textiles and apparel to rendering virtual actors to formulating hair cosmetics, understanding how these materials' physical properties affect their motion and appearance is crucial. Fiber-based structures behave differently from other materials. A knit fabric is much more extensible than its component yarns because the yarns can bend and slide into different macroscopic shapes. A head of long hair moves freely but smoothly, making and breaking millions of hair-hair contacts to produce a partly smooth, partly discontinuous overall motion. This research aims to improve the accuracy of cloth and hair simulation by fundamentally changing the underlying physical and computational models.The project follows an approach of measurement, modeling, simulation, and validation. Image-based measurement is used to capture complete fabric deformations. This data, together with the literature on yarn-level textile mechanics, is used to develop constitutive models based on the actual physics of fabric, which are simulated using advanced numerical methods not normally employed in textile simulation. The results are being evaluated both against the laboratory data and in the context of real problems in apparel design. By bringing together the tools of modern graphics and simulation with the detailed models of textile mechanics in a rigorous process of validation, this project is placing computer graphics cloth simulation on a firm scientific foundation for the future. Computational methods devised for fiber-fiber interactions are also being extended for efficient strand-level simulation of hair. After the simulations are validated, the project will examine approximations and algorithms to allow efficient simulation. The end result will be new, physics-based models for the mechanics of cloth and hair that are appropriate for visual applications.