Parametric Deformation Simulation via NURBS Skeletal Trees
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Solution Overview
Problem
Existing methods for modeling and animating complex objects, such as human faces, face challenges in simulating realistic deformation and interaction due to limitations in parametric representations, which lack high-level abstraction and intuitive control, and often treat deformation and interaction as distinct operations, requiring external entities for collision detection and response.
Innovation Solution
The use of Non-Uniform Rational B-Spline (NURBS) curves to simulate muscle movement and deformation, integrated with skeletal trees for a unified framework of object deformation and interaction, allowing for intuitive control and eliminating the need for external bounding entities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If parametric patches are used to model complex objects, then the object surface can be approximated, but the patch surface and object surface are not exactly the same and continuity constraints limit deformation
Solution Approach 1:
The patent merges the object surface representation with the deformation framework by using the object's own vertices and faces directly, rather than separating the surface approximation (patches) from the deformation control. This integration eliminates the mismatch between patch surface and object surface while maintaining continuity across boundaries.
Solution Approach 2:
Instead of approximating the object surface with patches and then deforming the patches, the patent inverts the approach by using the exact object vertices and faces as the deformation framework. The deformation is applied directly to the object geometry rather than to an approximate representation.
2Adaptability or versatility
If Free-Form Deformation (FFD) is used to deform objects, then global deformation can be achieved, but it is coarse and not suitable for modeling complex, subtle and local deformation
Solution Approach 1:
The patent segments the deformation control into local regions by associating different parametric curves with different portions of the facial anatomy. Each curve can be independently controlled to achieve subtle local deformations while maintaining global coherence through the hierarchical structure.
Solution Approach 2:
The patent introduces a hierarchical dimension to the deformation framework by organizing parametric curves into a tree structure with different levels. This allows control at multiple scales from global facial movements down to local subtle deformations, adding a dimension of control granularity.
3Device complexity
If parametric representations are used for deformation, then a limited number of control points determine every point on the surface, but static shapes are primarily parameterized and deformation and interaction are treated as distinct operations
Solution Approach 1:
The patent makes the parametric curve framework universal by designing it to handle multiple functions: representing static object geometry, controlling deformation through curve modification, and detecting collision through skeletal tree intersection testing. The same hierarchical curve structure serves all these purposes.
Solution Approach 2:
The patent merges previously distinct operations (deformation control and collision detection) into a unified framework based on hierarchical parametric curves. The skeletal tree structure derived from these curves serves both deformation animation and interaction simulation, eliminating the need for separate external bounding entities.
Data Source
AI summary
A method of using parametrical representations in modeling and animation is disclosed. This method is built directly on the inherent properties of parametric curves. Parametric curves are constructed and associated with geometric models, while at the same time the properties are used to represent the underlying mechanism of deformation. This method includes the steps of building parametrical representations on a geometric model, associating vertices of the model with different ones of the parametrical representations to effect movement thereof, and animating movement of the vertices to simulate relative motion therebetween.The invention discloses a method in which simulation of object interaction and object deformation can be integrated into a unified framework through skeletal trees. The method preprocesses a graphic object and segments the object into a number of contexts at surface slope and curvature discontinuities. Then, control points are generated to represent these contexts. Based on these control points, a skeletal tree of the object can be built. Assisted by spatial decomposition, the skeletal trees can be directly used in the simulation of object interaction.