Interactive editing of deformable simulations

Abstract

We present an interactive animation editor for complex deformable object animations. Given an existing animation, the artist directly manipulates the deformable body at any time frame, and the surrounding animation immediately adjusts in response. The automatic adjustments are designed to respect physics, preserve detail in both the input motion and geometry, respect prescribed bilateral contact constraints, and controllably and smoothly decay in spacetime. While the utility of interactive editing for rigid body and articulated figure animations is widely recognized, a corresponding approach to deformable bodies has not been technically feasible before. We achieve interactive rates by combining spacetime model reduction, rotation-strain coordinate warping, linearized elasticity, and direct manipulation. This direct editing tool can serve the final stages of animation production, which often call for detailed, direct adjustments that are otherwise tedious to realize by re-simulation or frame-by-frame editing.

Active Animations of Reduced Deformable Models with Environment Interactions

“…Active Deformable Body Animation is used by animators or artists to direct the animation while satisfying the physics-based constraints. Early works in this area [Barbič et al 2009[Barbič et al , 2012Bergou et al 2007;Schulz et al 2014] try to make the deformable body follow a user-provided animation by applying external forces. However, deformable bodies in real life, such as worms, snakes, and fishes, can only move themselves by generating internal forces.…”

“…It is well-known that spacetime optimization is prone to bad local minima leading to suboptimal solutions, except for simple cases [Barbič et al 2012]. In our algorithm, there are two energy terms that can result in the computation of bad local minima.…”

SimuLearn

“…More, morphing materials are often soft during transformation and have virtually infinite degrees of freedom, requiring high-resolution discrete models to avoid divergence, which further slows down the computation. While model reduction methods [2,44] can be used to achieve interactive FEA, they require pre-and re-processing whenever the model geometry is changed. Therefore, they are less ideal for supporting iterative design workflows.…”

Soft Folding

“…Because thin-plate forms are deformed from flat shapes, the traditional interface for designing thin-plate forms is based on deformation interfaces such as click-and-drag with physical simulation [BSG12] or geometric optimization [BK04]. However, these methods require the user to specify handles and drag them one-by-one to create designs, which is a tedious process.…”