Hierarchical motion brushes for animation instancing

Abstract

a bTime c Figure 1: Hierarchical motion brushes are a powerful tool for creating stylized animated content such as the fire of this example. The user painted a set of motion brushes (a) and uses them in a scene containing two hands (b). By only painting one stroke, a complex fire effect is created that erupts from one hand and reaches the other over time (c). AbstractOur work on "motion brushes" provides a new workflow for the creation and reuse of 3D animation with a focus on stylized movement and depiction. Conceptually, motion brushes expand existing brush models by incorporating hierarchies of 3D animated content including geometry, appearance information, and motion data as core brush primitives that are instantiated using a painting interface. Because motion brushes can encompass all the richness of detail and movement offered by animation software, they accommodate complex, varied effects that are not easily created by other means. To support reuse and provide an effective means for managing complexity, we propose a hierarchical representation that allows simple brushes to be combined into more complex ones. Our system provides stroke-based control over motion-brush parameters, including tools to effectively manage the temporal nature of the motion brush instances. We demonstrate the flexibility and richness of our system with motion brushes for splashing rain, footsteps appearing in the snow, and stylized visual effects.

Programmable Animation Texturing using Motion Stamps

“…Each spring's stretch factor is parametrized by the underlying cluster's velocity, its bending by the curvature of the cluster's trajectory, and its revolution angle is scripted to increase over time. Considering the spring shape as a 1‐frame animation, this example fits in the formal definition of motion stamps described in [MNB*14]. However, we are essentially producing the shape animation on the fly depending on the cluster data, instead of reusing animated examples.…”

“…Dynamic stylization can be time consuming when performed manually. Hence previous works have investigated the idea of linking parametric motions to larger scale movements designed by the animator [CHG14, MNB*14]. In these works, 2D or 3D animated stamps are controlled by sketching their positions or trajectories.…”

“…Chevalier et al propose an interface for designing 2D flows and controlling the parameters of overlaid 2D texture elements moving along the flow [CHG14]. Milliez et al allow the user to sketch the position of 3D animated meshes and control additional parameters such orientation using gesturing strokes [MNB*14]. We adopt the same “motion stamp” concept proposed by Milliez et al and extend it to work in the context of simulation enhancement.…”

“…The user can write scripts that we call motion shaders to parameterize animation instances. We use the formalism introduced by Milliez et al [MNB*14] and define elementary animations as motion brushes . A motion brush can be as flexible as a procedurally defined shape and as rigid as a baked 3D animation.…”

WorldBrush

“…Artistic brushing techniques make sketching more expressive by enabling the input of complex strokes with width, angle, and/or pressure. These techniques have been applied to a variety of specific content, such as pen-and-ink illustrations [Kazi et al 2012], textures [Sun et al 2013], images [Lu et al 2014], and short animations [Milliez et al 2014]. We consider that sketching relies more on pen-like sketches of 2D lines to control or produce results.…”