The paper can be found here.
1. “This paper introduces a method for automatically converting a smooth sketched curve into a 2D dynamic curve at stable equilibrium under gravity.” (second sentence, abstract)
2. The proper matching of arbitrary curly shapes to an appropriate physics-based model is difficult, and no analysis of stability equilibrium had been proposed.
3. There are two “key ideas”: a novel technique to fit a smooth piecewise circular arcs curve to a sketched curve, and a technique to compute the physical parameters of a dynamic rod model so that its stable rest shape under gravity exactly matches the fitted circular arcs curve.
4.a Automatically fits an arbitrary sketched curve into the stable rest shape of a dynamic rod under gravity, as shown with a hand-sketched treble clef and the tail of a cartoon monkey named Gibule.
4.b Can be applied to 2D animated movies and video games.
5. paper’s web site, with two videos, supplemental material, and executable code