← ArchivePaper2022
Character Articulation through Profile Curves
Spline-based rigging system where artists draw sparse curvenets that profile the surface, producing detail-preserving deformations used in Turning Red.
Abstract
Computer animation relies heavily on rigging setups that articulate character surfaces through a broad range of poses. Although many deformation strategies have been proposed over the years, constructing character rigs is still a cumbersome process that involves repetitive authoring of point weights and corrective sculpts with limited and indirect shaping controls. This paper presents a new approach for character articulation that produces detail-preserving deformations fully controlled by 3D curves that profile the deforming surface. Our method starts with a spline-based rigging system in which artists can draw and articulate sparse curvenets that describe surface profiles. By analyzing the layout of the rigged curvenets, we quantify the deformation along each curve side independent of the mesh connectivity, thus separating the articulation controllers from the underlying surface representation. To propagate the curvenet articulation over the character surface, we formulate a deformation optimization that reconstructs surface details while conforming to the rigged curvenets. In this process, we introduce a cut-cell algorithm that binds the curvenet to the surface mesh by cutting mesh elements into smaller polygons possibly with cracks, and then derive a cut-aware numerical discretization that provides harmonic interpolations with curve discontinuities.
How to read this
- Category
- Method: a curve-based character articulation and deformation system
- Contributions
- Detail-preserving deformations fully controlled by 3D curves that profile the deforming surface, via a spline-based rigging system of sparse articulated curvenets
- Quantifying deformation along each curve side independent of mesh connectivity, decoupling articulation controllers from the surface representation
- A deformation optimization that reconstructs surface detail while conforming to the rigged curvenets, with a cut-cell algorithm binding the curvenet to the mesh
- Context
- Continues the authors' rigging line including Sculpt Processing for Character Rigging (de Goes et al. 2020), shifting from point-weight and corrective-sculpt authoring toward direct profile-curve control.Builds on: Sculpt Processing for Character Rigging
- Correctness
- The key assumption is that sparse profile curves can capture and propagate desired deformation while staying mesh-independent; demonstrated as a production-grade rig (used on Turning Red per the note), with the usual caveat that authoring effort and behavior on extreme or unanticipated poses warrant scrutiny.
- Clarity
- Motivation and controls are intuitive; the curvenet analysis, deformation optimization and cut-cell binding need a careful second pass.
- How to read it
- First pass for the profile-curve control idea and how it replaces weight painting; second pass on the optimization and cut-cell algorithm if you want the formulation or to compare deformers.
Builds on
Related work
- Harmonic Coordinates for Character Articulation 2007 / SIGGRAPH
- Mesh-Based Inverse Kinematics 2005 / SIGGRAPH
- Avatar Reshaping and Automatic Rigging Using a Deformable Model 2015 / MIG
- Shaping the Elements: Curvenet Animation Controls in Pixar's Elemental 2023 / SIGGRAPH
Keywords
This page summarises the entry and links to its original source. The archive never hosts or redistributes the publication itself.Show it in the full archive list →