A general two-stage initialization for sag-free deformable simulations
A general two-stage initialization for sag-free deformable simulations
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DOI：
10.1145/3528223.3530165
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发表时间：
2022-07
期刊：
影响因子：
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通讯作者：
J. Hsu;Nghia Truong;Cem Yuksel;Kui Wu
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文献类型：
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作者：
J. Hsu;Nghia Truong;Cem Yuksel;Kui Wu
初始化可变形对象的模拟涉及将所有内力的静止状态设置为对象的静止形状。然而，通常没有明确地提供静止形状。在没有初始化形状的情况下，通常将给定的初始形状作为静止形状进行初始化。这会导致下垂，即模拟一开始就在重力作用下发生的不希望的变形。现有的解决下垂问题的方法局限于特定的仿真系统和材料模型，大多数不能处理摩擦接触，并且需要求解昂贵的全局非线性优化问题。我们介绍了一种新的解决方案，可以应用于各种模拟系统和材料的下垂问题。我们的方法的主要特点是，我们避免了解决一个全局非线性优化问题进行初始化在两个阶段。首先，我们使用全局线性优化静态平衡。材料定义的任何非线性都在局部阶段处理，有效地并行解决了许多小的局部问题。值得注意的是，我们的方法可以正确地处理摩擦接触的数量级比以前的工作更快。我们表明，我们的方法可以应用于各种模拟系统，通过提出的例子与质量弹簧系统，布料模拟，有限元法，材料点法，和基于位置的动态。
Initializing simulations of deformable objects involves setting the rest state of all internal forces at the rest shape of the object. However, often times the rest shape is not explicitly provided. In its absence, it is common to initialize by treating the given initial shape as the rest shape. This leads to sagging, the undesirable deformation under gravity as soon as the simulation begins. Prior solutions to sagging are limited to specific simulation systems and material models, most of them cannot handle frictional contact, and they require solving expensive global nonlinear optimization problems. We introduce a novel solution to the sagging problem that can be applied to a variety of simulation systems and materials. The key feature of our approach is that we avoid solving a global nonlinear optimization problem by performing the initialization in two stages. First, we use a global linear optimization for static equilibrium. Any nonlinearity of the material definition is handled in the local stage, which solves many small local problems efficiently and in parallel. Notably, our method can properly handle frictional contact orders of magnitude faster than prior work. We show that our approach can be applied to various simulation systems by presenting examples with mass-spring systems, cloth simulations, the finite element method, the material point method, and position-based dynamics.