59703933
Anatomy-based 3D facial modeling for expression animation
In this paper we propose a new hierarchical 3D facial model that conforms to the human facial anatomy for realistic facial expression animation. The facial model has a hierarchical biomechanical structure, incorporating a physically-based approximation to facial skin tissue, a set of anatomically-motivated facial muscle actuators and underlying skull structure. The deformable skin model has multi-layer structure to approximate different types of soft tissue. It takes into account the nonlinear stress-strain relationship of the skin and the fact that soft tissue is almost incompressible. Different kinds of muscle models have been developed to simulate the distribution of the muscle force on the skin due to muscle contraction. By the presence of the skull model, our facial model takes advantage of both more accurate facial deformation and the consideration of facial anatomy during the interactive definition of facial muscles. Under the muscular force, the deformation of the facial skin is evaluated by solving the governing dynamic equation numerically. To improve computational efficiency, we use a localized, semi-implicit integration method which allows a larger time step to be taken in the simulation while retaining stability. The dynamic facial animation algorithm runs at an interactive rate with flexible and realistic facial expressions to be generated.
15173958
Reanimating real humans: automatic reconstruction of animated faces from range data
Advances in 3D scanning technology have enabled automatic capture of complex 3D models such as human faces with highly detailed surfaces. However, the range data cannot be used easily for animatable face modeling due to the absence of functional animation structure and dense surface data. The paper presents an automatic facial model adaptation algorithm for reconstruction of animatable individualized 3D facial models from range data. A generic model that represents both the face shape and anatomical structure serves as the starting point for the adaptation algorithm. The global adaptation transforms the generic model to align it with the scan data in the 3D space based on measurements between a set of 3D landmarks. The local adaptation then deforms the skin mesh of the generic model to fit all of its vertices to the scan surface. The underlying muscle structure is automatically adapted and facial texture is transferred. The reconstructed 3D face resembles the shape and color of a real individual and can be animated immediately with muscle parameters.
5771110
An example-based anthropometric model for face shape synthesis
This paper presents a novel method for generating varied, realistic geometric face models by synthesizing facial features according to anthropometric parameters. Our method takes as examples scanned 3D face models in order to exploit the parameter-to-geometry correlations that are presented in the real faces. A two-step model fitting approach is used to establish correspondences among scanned models. We transform the data sets of facial feature shape into vector space representations by applying a principal component analysis (PCA). For each facial feature, we compute a set of anthropometric measurements to parameterize the exemplar meshes into a measurement space. Using PCA coefficients as a compact shape representation, we approach the shape synthesis problem by forming scattered data interpolation functions that are devoted to the generation of desired shape by taking the anthropometric parameters as input.
5849129
A new physical model with multilayer architecture for facial expression animation using dynamic adaptive mesh
This paper presents a new physically-based 3D facial model based on anatomical knowledge which provides high fidelity for facial expression animation while optimizing the computation. Our facial model has a multilayer biomechanical structure, incorporating a physically-based approximation to facial skin tissue, a set of anatomically-motivated facial muscle actuators, and underlying skull structure. In contrast to existing mass-spring-damper (MSD) facial models, our dynamic skin model uses the nonlinear springs to directly simulate the nonlinear visco-elastic behavior of soft tissue and a new kind of edge repulsion spring is developed to prevent collapse of the skin model. Different types of muscle models have been developed to simulate distribution of the muscle force applied on the skin due to muscle contraction. The presence of the skull advantageously constrain the skin movements, resulting in more accurate facial deformation and also guides the interactive placement of facial muscles. The governing dynamics are computed using a local semiimplicit ODE solver. In the dynamic simulation, an adaptive refinement automatically adapts the local resolution at which potential inaccuracies are detected depending on local deformation. The method, in effect, ensures the required speedup by concentrating computational time only where needed while ensuring realistic behavior within a predefined error threshold. This mechanism allows more pleasing animation results to be produced at a reduced computational cost.
18794722
Word Sense Language Model for Information Retrieval
This paper proposes a word sense language model based method for information retrieval. This method, differing from most of traditional ones, combines word senses defined in a thesaurus with a classic statistical model. The word sense language model regards the word sense as a form of linguistic knowledge, which is helpful in handling mismatch caused by synonym and data sparseness due to data limit. Experimental results based on TREC-Mandarin corpus show that this method gains 12.5% improvement on MAP over traditional tf-idf retrieval method but 5.82% decrease on MAP compared to a classic language model. A combination result of this method and the language model yields 8.92% and 7.93% increases over either respectively. We present analysis and discussions on the not-so-exciting results and conclude that a higher performance of word sense language model will owe to high accurate of word sense labeling. We believe that linguistic knowledge such as word sense of a thesaurus will help IR improve ultimately in many ways.
40389264
Application of Efficient Numerical Methods in Solution of Ordinary Differential Equations for Modeling Electrical Activity in Cardiac Cells
There is a large number of ordinary differential equations (ODEs) characterize the electrical behavior generated by ionic movements in human myocardial cell. In this paper, several approaches were investigated in order to improve the efficiency of solving the ODE systems for ten Tusscher et al.’s ionic model of human ventricular tissue. By using non-standard finite difference (NSFD) scheme, the stiffness of the ODEs system will be successfully reduced, so a larger step-size can be used. A popular multi-step method called backward differentiation formulation (BDF) was also incorporated into the computational model for testing the largest possible time steps. The results show that NSFD can be as much as 10 times more efficient than standard forward Euler in single cell model simulation while maintaining an acceptable level of accuracy. The investigation of BDF method shows that a large step size is not recommended for the single cell simulation application. All solvers were coupled to the partial differential equations for the complete simulation of heart tissue, and such computation scheme may be a good calculation technique in heart modeling and simulation.
17166111
The Interaction between Chinese Export Price and World Import Price of Tangerines
With the accelerating of economic globalization, the effect of foreign factors on Chinese tangerines export is more and more obvious, which is mainly expressed as the fluctuation of Chinese tangerines export price. The article uses SVAR, impulse response analysis and variance decomposition to analyze the interaction between Chinese export price and world import price of tangerines from 1961 to 2007. The research shows that: (1) periodicities of the two prices are obvious; (2) fluctuation frequency of Chinese export price is high and its fluctuation range is low, while that of world import price is just the opposite; (3) changes of Chinese export price are mainly affected by its own fluctuation, while world import price is not only affected by its own fluctuation but also shocked by Chinese export price; (4) fluctuation characteristics of two prices indicate that there is serious price distortion in world tangerines market, so it requires carrying on multilateral negotiation under WTO agreement to eliminate trade barriers in tangerines market and to improve the world welfare.
14748203
A history sensitive cascade model in diffusion networks
Diffusion is a process by which information, viruses, ideas and new behavior spread over social networks. The traditional independent cascade model gives activated nodes a one-time chance to activate each of its neighboring nodes with some probability. This paper extends the traditional cascade model to be history dependent. We propose a new model called the History Sensitive Cascade Model (HSCM) that allows activated nodes to receive more than a one-time chance to activate their neighbors. HSCM provides 1) a polynomial algorithm for calculating the probability of activity for any arbitrary node at any arbitrary time in tree structure graphs, and 2) a Markov model for calculating the probability in general graphs. Finally, we perform an empirical study on HSCM under different network settings. These simulations have showed its power to observe and explain the emergent phenomena in the macro level when changing parameters in the micro level.
5082890
An integration architecture for process manufacturing systems
Given the significant differences between discrete and process manufacturing industries, specific integration architectures are required to accommodate the unique characteristics of process industries. In this paper, an architecture that encompasses view models, flow models and O-O models is developed, which gradually specifies the evolving design details through successive lifecycle stages of process manufacturing systems. In the architecture, products are distinctly modelled to reflect the impact of product data and to facilitate the development of customized products. A combination of object and agent concepts is adopted for building the models of process manufacturing systems. System constituent elements are respectively modelled as two types of entities: Namely the objects and agents. Objects are used to describe the passive constituent entities that possess no autonomy and conduct no functions, whereas agents are used to model the active entities that possess decision-making capabilities and perform operations on objects. One important advantage of the architecture is that it provides executable models at the implementation stage, which can be directly converted into application programs coded in object-oriented languages. Some models of the architecture are further discussed in depth and an information infrastructure based on CORBA standards is proposed for integrating the distributed data sources.