Abstract
Virtual characters are 3D geometric models of characters. They have a lot of applications in multimedia. In this paper, we propose a new physics-based deformation method and efficient character modelling framework for creation of detailed 3D virtual character models. Our proposed physics-based deformation method uses PDE surfaces. Here PDE is the abbreviation of Partial Differential Equation, and PDE surfaces are defined as sculpting force-driven shape representations of interpolation surfaces. Interpolation surfaces are obtained by interpolating key cross-section profile curves and the sculpting force-driven shape representation uses an analytical solution to a vector-valued partial differential equation involving sculpting forces to quickly obtain deformed shapes. Our proposed character modelling framework consists of global modeling and local modeling. The global modeling is also called model building, which is a process of creating a whole character model quickly with sketch-guided and template-based modeling techniques. The local modeling produces local details efficiently to improve the realism of the created character model with four shape manipulation techniques. The sketch-guided global modeling generates a character model from three different levels of sketched profile curves called primary, secondary and key cross-section curves in three orthographic views. The template-based global modeling obtains a new character model by deforming a template model to match the three different levels of profile curves. Four shape manipulation techniques for local modeling are investigated and integrated into the new modelling framework. They include: partial differential equation-based shape manipulation, generalized elliptic curve-driven shape manipulation, sketch assisted shape manipulation, and template-based shape manipulation. These new local modeling techniques have both global and local shape control functions and are efficient in local shape manipulation. The final character models are represented with a collection of surfaces, which are modeled with two types of geometric entities: generalized elliptic curves (GECs) and partial differential equation-based surfaces. Our experiments indicate that the proposed modeling approach can build detailed and realistic character models easily and quickly.
Highlights
IntroductionTemplate-based, and physics-based methods have been developed to raise efficiency, increase details, and improve realism of virtual character modeling
Modeling of virtual characters is essential in many multimedia applications
We introduce our proposed stepwise approach into template-based global modelling to deal with the silhouettes in three orthographic views which deforms a template 3D model to fit 2D primary profile curves, and uses secondary profile curves and key cross-section profile curves to further modify the deformed template model
Summary
Template-based, and physics-based methods have been developed to raise efficiency, increase details, and improve realism of virtual character modeling. We will develop a new approach to tackle this unsolved problem, achieve analytical PDE solutions to carry out efficient physics-based deformations within the regions of both 2-sided and 4-sided patches, and investigate degenerated PDE surfaces called generalized elliptic curve-based interpolation surfaces which are generated from key cross-section profile curves. With the proposed sketch-guided, template-based, and PDE-based techniques and generalized elliptic curve-based interpolation surfaces, we investigate four local modeling techniques to achieve shape manipulations efficiently. The contributions of this paper can be summarized as: (1) sketch-guided global modeling, (2) template-based global modeling, (3) analytical PDE-based deformations, (4) generalized elliptic curve-based interpolation surfaces, and (5) local shape manipulation techniques
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