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Sketch-Based Controllers for Blendshape Facial Animation
Puts sketched controllers on the blendshape face itself, the opening move in Cetinaslan's line of work on making weight editing feel like drawing rather than hunting through sliders.
Abstract
The blendshape approach is a widely used technique to generate realistic facial animation. However, creating blendshape facial animations using traditional weight editing tools requires either memorizing the function of a large number of parameters, or a trial-and-error search in a high-dimensional space. Direct manipulation interfaces address this problem, allowing the artist to directly move and pin manipulators placed on the surface of the face. Placing manipulators is an open-ended and slightly unnatural task for artists however. In this paper we present a sketch-based approach to this problem, inspired by artists' brush painting on canvas. In this approach the artist simply sketches directly onto the 3D model the positions of the manipulators that they feel are needed to produce particular facial expression. The manipulators activate the blendshapes in the model and allow the user to interactively create the desired facial poses by a dragging operation in screen coordinates. Our hybrid method can be used with any blendshape facial model and allows producing expeditious manipulation in an intuitive way.
How to read this
- Category
- Eurographics short paper introducing sketch-based control of a blendshape face rig.
- Contributions
- Controllers that are sketched onto the facial model itself rather than laid out in a slider panel.
- A binding from those sketched controllers to blendshape weights, so drawing sets the weights.
- An argument that the authoring cost of blendshape animation sits in the interface, not in the model.
- Context
- The starting point of Cetinaslan's decade of work on blendshape interfaces, and it inherits from two places at once. The sketching idea comes from miranda-sketch-express-2011, in the same Porto group. The blendshape formalism and its known problems come from lewis-anjyo-blendshape-star-2014, the survey that Lewis, a co-author here, wrote the year before.Builds on: Sketch Express: Facial Expressions Made Easy · Practice and Theory of Blendshape Facial Models
- Correctness
- A short paper, so the evidence is a demonstration rather than a study. The claim that sketching beats sliders is plausible and untested here. Note also that this early version still edits weights globally, and the instability that follows from that is precisely what the later papers in the line spend their time fixing.
- Clarity
- Compact, four pages, easy to read in one sitting. It states the idea and shows it working without much apparatus.
- How to read it
- First pass: read the whole thing, it is short enough. Second pass: only to place it in the line, by asking what problem it leaves open. That question is answered by cetinaslan-transposition-blendshape-2017 and cetinaslan-direct-manipulation-2018, so read this one as the setup for those.
Builds on
Related work
Keywords
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