SGER: Combined Micro- and Macro-Model for Simulating Cloth by Deriving Mechanical Behavior from Underlying Fabric Structure

计算机动画和特效已经取得了长足的进步。 在某些情况下，合成或虚拟演员被整合到真人电影中。这就需要精确地建模和渲染服装。此外，服装行业自动化程度的提高也需要更复杂的设计和制造技术，这反过来又需要对布料建模进行研究。这项研究将为计算机图形学的布料建模提供更严格的基础，并将为服装行业带来额外的利益。这项研究将通过两阶段系统为服装面料设计创造一个有凝聚力的环境。 第一阶段将从底层结构确定布料的基本属性，然后第二阶段将使用特定面料的定制模型来逼真地模拟服装的动态行为。 第一阶段，微观模型，将模拟织物一小部分中纱线的变形，并分析样品在各种载荷条件下的结果。 然后，在第二阶段（宏模型）中使用描述布料作为连续体的变形行为的关系来制作完整服装的动画。 第一阶段的微观模型将比目前纺织研究中使用的具体设置更一般。 特别是，所提出的模型将考虑纱线与任意的纱线路径，有捻和滑动接触摩擦。对机织物的经验证据和观察表明，后两个特征在织物的整体外观和性能中具有实质性作用，但在纺织品或计算机图形学的任何先前工作中，都没有考虑过对织物中的纱线进行建模。 一个相关的问题是如何处理接触，因为纱线几乎在任何地方都非常接近，从而产生牵引力。 第二阶段将使用基于第一阶段结果的改进模型来模拟织物。 重点将放在本构方程和结合耦合非线性行为。永久性皱纹等功能将在以后的过程中添加。 其他增强包括局部反射率、透明度和作为局部应变的函数的抗风性。 实际关系将在第一阶段期间导出，但随后在此宏模型模拟中的渲染或计算外力期间使用。

Great strides have been made in computer animation and special effects. In some cases, synthetic or virtual actors have been integrated into live action films. This raises the need to accurately model and render clothing. In addition, increases in automation in the garment industry create a need for more sophisticated design and manufacturing techniques, which in turn require research in cloth modeling. This investigation will bring a more rigorous basis for cloth modeling to computer graphics, and will have the added benefit of being of interest to the garment industry.This research will create a cohesive environment for designing fabrics for garments through a two-stage system. The first stage will determine the essential properties of cloth from its underlying structure and then the second stage will use a tailored model of the specific fabric to realistically simulate the dynamic behavior of a garment. The first stage, the micro-model, will simulate the deformation of the yarns in a small section of cloth and will analyze the results of subjecting the sample to various loading conditions. The relations describing the deformation behavior of cloth as a continuum will then be used in the second stage, the macro-model, to animate a full garment. The first stage micro-model will be more general than the specific setups currently used in textile research. In particular, the proposed model will consider yarns with arbitrary yarn paths that have twist and sliding contacts with friction. Empirical evidence and observation of woven fabrics have shown that the latter two features have a substantial role in the overall look and behavior of cloth, but neither has been considered in any previous work in textiles or computer graphics for modeling yarns in fabrics. A related issue is how to deal with the contacts, since the yarns will be in close proximity almost everywhere, contributing to traction forces. The second stage will simulate fabric using the revamped model based on the results of the first stage. The main focus will be on the constitutive equations and incorporating coupled nonlinear behavior. Features such as permanent wrinkles will be added in a later pass. Additional enhancements include local reflectance, transparency, and wind resistance as a function of the local strain. The actual relations would be derived during the first stage but then used during rendering or computation of external forces in this macro-model simulation.