Facial Blendshape Transfer via Virtual Triangles
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Solution Overview
Problem
Existing facial deformation transfer techniques for computer-animated characters face challenges such as contact-awareness issues, leading to penetrations and separations, and lack of smoothness, resulting in crumpling artifacts, particularly at highly deformed areas like eyelids and mouth corners, which increase manual labor in facial modeling and rigging.
Innovation Solution
The method introduces virtual triangular meshes and weighted Laplacian regularization to solve a linear system equation, ensuring contact awareness and smoothness in deformation transfer, by appending virtual triangles to the mesh and incorporating Laplacian energy terms to preserve spatial relationships and smoothness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional deformation transfer technique is used, then productivity is improved by automating facial blendshape transfer, but manufacturing precision deteriorates due to penetration artifacts and crumpling
Solution Approach 1:
The patent introduces virtual triangles as intermediary elements between existing mesh triangles to mediate the deformation transfer process. These virtual triangles act as buffers that prevent direct contact between deforming mesh surfaces, thereby eliminating penetration artifacts while maintaining the automated transfer workflow. The virtual triangles are dynamically created and removed based on contact detection, serving as temporary mediators during the deformation process.
Solution Approach 2:
The patent modifies the deformation transfer by introducing Laplacian smoothing parameters and contact constraints as additional control variables. By adjusting these parameters, the system maintains mesh smoothness and prevents crumpling artifacts while preserving the efficiency of automated transfer. The parameter changes include adding Laplacian energy terms to the optimization function and incorporating contact constraint forces.
2Manufacturing precision
If manual facial modeling is performed for each character, then manufacturing precision is maintained through artistic control, but productivity deteriorates due to enormous labor requirements
Solution Approach 1:
The patent creates high-quality facial deformations by copying the deformation pattern from a single expertly modeled base character and transferring it to multiple other characters. The virtual triangle mechanism ensures that the copied deformation maintains contact awareness and smoothness, preserving the quality of the original artistic work while enabling efficient replication across many characters without requiring manual remodeling.
Solution Approach 2:
The patent segments the facial mesh into regions with and without virtual triangles based on contact detection. This segmentation allows the system to apply different deformation handling strategies to different regions: virtual triangles are inserted in contact-prone areas to prevent penetration, while other regions use standard deformation transfer. This selective segmentation maintains overall deformation quality while enabling automated processing.
3Reliability
If virtual triangles are appended to mesh, then contact awareness is improved preventing penetration, but device complexity increases due to additional mesh processing
Solution Approach 1:
The patent implements a dynamic virtual triangle system where triangles are added and removed based on real-time contact detection during the deformation process. Virtual triangles are dynamically inserted when contact is detected between mesh surfaces and removed when contact is no longer present. This dynamic approach maintains contact constraint accuracy only where needed, rather than permanently increasing mesh complexity across the entire model.
Solution Approach 2:
The patent applies virtual triangles only partially to specific regions of the mesh where contact issues are detected, rather than applying them uniformly to the entire mesh. This partial action approach maintains contact awareness in critical areas (like eyelids and mouth corners) while avoiding unnecessary complexity in regions where contact constraints are not needed, thus balancing reliability improvement with complexity management.
Data Source
AI summary
A method for deformation transfer of a source three-dimensional (3D) geometry to a target 3D geometry for computer-implemented blendshapes animation includes solving a linear system equation in which blendshapes deformation transfer with a virtual triangular mesh is performed, where the virtual triangular mesh having a plurality of virtual triangles is assigned to a prescribed region of an animated figure that are presented by a computer-generated mesh, and/or in which blendshapes deformation transfer is performed with Laplacian smoothing.