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.
40211124
Real-time physically-based facial expression animation using mass-spring system
We propose a physically-based approach based on anatomical knowledge for real-time facial expression animation. The facial model incorporates a physically-based approximation to facial skin and a set of anatomically-motivated facial muscles. The skin is modeled by a mass-spring system with nonlinear springs which have a biphasic stress-strain relationship to simulate the elastic dynamics of real facial skin. Facial muscles are modeled as forces deforming the spring mesh. Based on the action units (AUs) of the facial action coding system (FACS), various expressions can be generated by a combination of contractions of a set of facial muscles. Lagrangian mechanics governs the dynamics, dictating the deformation of the facial surface in response to muscle forces. Simulation results show real-time facial deformation as well as realistic expression animation.
20139173
Muscle-driven modeling of wrinkles for 3D facial expressions
Facial expression animation considering wrinkle formation is an aspiring goal and a challenging task. This paper presents a new geometric wrinkle model that is defined according to facial muscle anatomy for efficient simulation of dynamic wrinkles within expressions. Our method is applied to an anatomy-based face model with a multi-layer structure of skin, muscles, and skull. The location and orientation of the wrinkles are automatically determined based on muscle contraction and its influence on the skin. Corresponding to two types of facial muscles, the geometric wrinkle model governs evolution of wrinkle amplitude in the local deformed face regions. It provides intuitive parameters for easy control over wrinkle characteristics by taking into account the properties of real wrinkles. Results show that this method enables realistic wrinkles synchronized with facial movements to be dynamically simulated and rendered at an interactive rate.
17357435
Improving Videophone Transmission over Multi-Rate IEEE 802.11e Networks
In this paper, we propose an adaptive system for improving videophone transmission over EDCA. We consider that a videophone contains a constant bit rate (CBR) voice source and a rate-adaptive video source. Two issues are addressed in this research. Firstly, how to solve the AP bottleneck problem, and secondly, how to adjust video source rate to improve the network performance. For the first issue, we propose the adjustment of the transmission opportunity (TXOP) to give AP a higher priority in voice transmission in order to eliminate the AC3 transmission bottleneck at the AP. For the second issue, our principle is to guarantee the throughput of voice traffic while transmitting as much video traffic as possible. Moreover, we consider more realistic multi-rate WLANs, where multiple transmission rates are used in the PHY layer depending on the underlaying channel conditions.
14581660
An Improved Physically-Based Method for Geometric Restoration of Distorted Document Images
In document digitization through camera-based systems, simple imaging setups often produce geometric distortions in the resultant 2D images because of the nonplanar geometric shapes of certain documents such as thick bound books, rolled, folded, or crumpled materials, etc. Previous work [1], [2], [3], [4] has demonstrated that arbitrary warped documents can be successfully restored by flattening a 3D scan of the document. These approaches use physically-based or relaxation-based techniques in their flattening process. While this has been demonstrated to be effective in rectifying the image content and improving OCR, these previous approaches have several limitations in terms of speed and stability. In this paper, we propose a distance-based penalty metric to replace the mass- spring model and introduce additional bending resistance and drag forces to improve the efficiency of the existing approaches. The use of Verlet integration and special plane collision handling schemes also help to achieve better stability without sacrificing efficiency. Experiments on various document images captured from books, brochures, and historical documents with arbitrary warpings have demonstrated large improvements over the existing approaches in terms of stability and efficiency.
17517047
From range data to animated anatomy-based faces: a model adaptation method
This paper presents a new method for reconstructing animated, anatomy-based facial models of individuals from range data with minimal manual intervention. A prototype model with a multi-layer skin-muscle-skull structure serves as the starting point for our method. After the global adaptation, the skin mesh of the prototype model is represented as a dynamic deformable model which is deformed to fit scanned data according to internal force stemming from the elastic properties of the surface and external forces produced from the scanned data points and features. The underlying muscle layer that consists of three types of facial muscles is automatically adapted. According to the adapted skin and muscle structures, a set of automatically generated skull feature points is transformed to drive a volume morphing of the template skull model for skull fitting. The reconstructed model realistically reproduces the shape and features of a specific person and can be animated instantly.
36668943
Parallel Solution in Simulation of Cardiac Excitation Anisotropic Propagation
Solution in simulation of cardiac excitation anisotropic propagation throughout the ventricular myocardium is computationally very expensive that demands the introduction of a high performance computing techniques. In this study, a canine ventricle model was constructed features a realistic anatomical structure, including intramural fiber rotation and a conduction system. By using operator-splitting scheme, adaptive time step and backward differentiation formulation techniques in a parallel implement, we solved mondomain equation successfully. The stimulation produced isochrone's map is close to the clinical record that obtained from the non-contact mapping system of Ensite 3000. The results show that the proposed methods can successfully be used to simulate heart excitation anisotropic propagation in three-dimensional anatomical large tissue size.
35510017
A Link-Based Rank of Postings in Newsgroup
Discussion systems such as Usenet, BBS, Forum are important resources for information sharing, view exchanging, problem solving and product feedback, etc. on Internet. The postings in newsgroups on Usenet represents the judgments and choices of participators. The structure of postings could provide helpful information for the users. In this paper, we present a method called PostRank to rank the postings based on the structure of newsgroup. Its results correspond to the eigenvectors of the transition probability matrix and the stationary vectors of the Markov chains. It could provide useful global information for the newsgroup and it can be used to help the users access information in it more effectively and efficiently. This method can be also applied on other discussion systems. Some experimental results and discussions on real data sets collected by us are also provided.
31009913
Synthesis of 3D faces using region-based morphing under intuitive control
This paper presents a new region-based method for automatically synthesizing varied, natural looking 3D human face models by morphing local facial features according to intuitive control parameters. We automatically compute a one-to-one vertex correspondence among the unregistered face scans in a large database by deforming a generic mesh to fit the specific person's face geometry in a global-to-local fashion. With the obtained correspondence, we transform the generated data sets of feature shapes into vector space representations. We parameterize the example models using the face anthropometric measurements that reflect the facial physical structure, and predefine the interpolation functions for the parameterized example models based on radial basis functions. At runtime, the interpolation functions are evaluated to efficiently generate the appropriate feature shape by taking the anthropometric parameters as input. We use a shape blending approach for generating a seamlessly deformed mesh around the feature region boundary. The correspondence among all example textures is established by parameterizing the 3D generic mesh over a 2D image domain. The new feature texture with desired attributes is synthesized by interpolating the example textures. Our 3D face synthesis method has several advantages: (1) it regulates the naturalness of synthesized faces, maintaining the quality existing in the real face examples; (2) the region-based morphing and comprehensive face shape and texture control parameters allow more diverse faces to be generated readily; and (3) the automatic runtime face synthesis is efficient in time complexity and performs fast. Copyright © 2006 John Wiley & Sons, Ltd.
17199895
An Active Storage System for High Performance Computing
Traditionally, active storage devices execute custom application code on large amounts of data by utilizing the unused processing power of the storage nodes. For computation-intensive applications, the performance might be quite low due to insufficient processing power on the storage devices. In this paper we present a reconfigurable computing solution that can provide flexible, high-performance processing capabilities for the storage nodes. We have made a change over the existing active storage framework for object-based storage device by off loading computation-intensive request-driven services to a reconfigurable hardware accelerator. In the experiment, we use two applications (AES encryption and FFT) as the case studies, and the results show that the reconfigurable computing-based system can dramatically increase the performance comparing with the traditional software-based active storage systems.
16162037
Ranking-Based Statistical Localization for Wireless Sensor Networks
This paper studies Ranking-Based localization method, which, as a special case of common Range-Based localization methods, statistically estimates node positions using the ranking-order constraints rather than the actual values of network measurements. Through extensive empirical evaluation, the advantages of Ranking-Based approach over traditional Range-Based approaches under extreme network conditions are verified. Ranking-Based approach turns out to be more robust to measurement insufficiency and more immune to measurement noise.