Cloth Animation with Time-dependent Persistent Wrinkles

TL;DR

The paper addresses the realism gap in cloth animation by modeling time dependent persistent wrinkles that arise from the interplay between internal friction and plasticity. It introduces a physics inspired framework with time dependent friction and elastoplastic bending to produce wrinkles that sharpen and persist with deformation duration, including a dwell effect and time evolving yield. Key contributions are the time dependent friction model, the time dependent plastic hardening model, and the first cloth simulator capable of generating complex time dependent persistent wrinkles across fabrics and garments. Experiments validate spatial and temporal plausibility across materials and motions, highlighting the method's potential for high fidelity animation and fashion design while noting areas for quantitative calibration and broader integration.

Abstract

Persistent wrinkles are often observed on crumpled garments e.g., the wrinkles around the knees after sitting for a while. Such wrinkles can be easily recovered if not deformed for long, and otherwise be persistent. Since they are vital to the visual realism of cloth animation, we aim to simulate realistic looking persistent wrinkles. To this end, we present a physics-inspired fine-grained wrinkle model. Different from existing methods, we recognize the importance of the interplay between internal friction and plasticity during wrinkle formation. Furthermore, we model their time dependence for persistent wrinkles. Our model is capable of not only simulating realistic wrinkle patterns, but also their time-dependent changes according to how long the deformation is maintained. Through extensive experiments, we show that our model is effective in simulating realistic spatial and temporal varying wrinkles, versatile in simulating different materials, and capable of generating more fine-grained wrinkles than the state of the art.

Figures (23)

• Figure 1: By using the exponential function to model friction dwell (\ref{['eq:slip-stick']} and figure a) and time-dependent plastic hardening effects (\ref{['eq:Kh']} and figure b), our cloth simulator can plausibly reproduce the relationship between cloth (Log) persistent wrinkles recovery percentage and (Log) pressing time (deformation duration) measured on real cloths (red curves in figure c and d from levison1962some). The pink curve in figure c approximates the measurement in levison1962some (red curve), and its pattern is similar to the simulated curves in figure a and b.
• Figure 2: Our simulator can realistically simulate time-dependent wrinkles (a-s, b-s, c-s, d-s) observed in the real clothes (a, b, c, d) in different deformations. In both real and simulated clothes, folding or compressing clothes for a long duration (30 mins) makes the wrinkles sharper. The wrinkles formed on Denim by compressing (d) is sharper than those on cotton clothes (b, d), and our simulator can reproduce these observations (b-s, d-s). Bigger figures in SM.
• Figure 3: (a) An originally wrinkleless rectangle cloth falls into a cylindrical container due to its self-weight; (b) The cloth is folded moderately due to collision; (c) To cause extreme deformations, we compress the cloth after it falls on the ground.
• Figure 4: The wrinkles on the cloth after lifting it. (a) Immediately lift the cloth after folding moderately; (b) Lift the cloth after keeping the moderate deformation for 500s; (c) Immediately lift the cloth after being compressed by the heavy weight; (d) Lift the cloth after compressing it for 500s.
• Figure 5: Trousers simulation. (a) The trousers on A-pose human body does not have wrinkles; (b) Lifting a leg deforms the trousers moderately; (c) Sitting down causes larger deformations.