人体头颈计算机模型的建立与有限元分析

本文首先阐述了人体头颈有限元计算模型的建立依然是有限元分析方法解决生物力学问题过程中面临的难题.然后利用CT扫描技术,Mimics软件的自动建模功能和计算机软件Geomagic逆向建模方法准确地、快速地建立了人体头颈部的几何模型.最后在有限的计算机硬件资源下利用有限元分析软件的前处理器建立了与人体头颈实际状态相近的有限元计算模型,并通过有限元分析软件ANSYS对所建的头颈有限元动力响应分析,得到与试验大致相符的头部位移响应曲线,验证了所建的人体头颈有限元计算机模型,同时得到了人体头部和颈部在受到冲击载荷下的任何时间变形和应力,为头颈部损伤的临床提供了重要的参考.     

面向艺术与设计虚拟人技术比较研究

在面向艺术与设计虚拟人技术领域,建模、皮肤变形、运动控制是其基本问题。首先介绍了基于经验知识、人体解剖学以及基于物理模拟的虚拟人研究方法,然后介绍了基于样本插值的虚拟人研究方法。最后对两种方法进行了比较研究,并展望了未来的发展方向。     

基于智能结构的BIA人体健康测评系统研究与设计

针对人体健康评价中数据庞大、受影响因素多等问题,从智能特征建模方法入手结合专家系统理论提出一种智能结构人体健康评价系统模型。运用生物电阻抗技术综合人体总阻抗与分段阻抗相结合的测量方法得到人体生理参数;仿人思维模式把人体健康测评这一复杂任务系统分解为决策、测评两个层次,决策层通过定义有限状态机的转移方式,确定系统所属状态,测评层采用层次分析获取健康评价模式,有效解决了人体健康测评中的多任务、不确定的问题,为解决一类复杂系统的建模问题提供了一个解决思路。     

虚拟人合成研究进展

虚拟人是人在计算机生成空间(虚拟环境)中的几何特性与行为特性的表示.虚拟人合成研究的内容主要包括逼真人体模型与逼真人体运动行为.文中介绍了人体建模方法、人体运动行为生成方法的发展过程,给出了基于实例的人体建模与人体运动行为建模的研究进展,以及这些研究成果的应用例子,最后列举了几个前沿研究问题.     

步态序列图像中人体下肢关节点的定位

研究人的步态识别优化问题,针对下肢关节点定位成为人体运动跟踪与分析中,存在精度不确切的问题.为解决上述问题,提出步态序列图像处理技术.首先从图像序列中提取人体目标,并建立下肢骨架模型和小腿轮廓模型;利用一种基于传统动态建模的圆周摆算法[1]结合帧序列的连续性以及小腿轮廓数据自动检测膝关节位置和踝关节的粗略位置.通过仿真表明,小腿轮廓模型的匹配计算在踝关节预测点的周围搜索出精确位置,并验证了方法效果很好,为设计提供了依据.     

三维计算机动画中人体建模方法的研究

人体建模是计算机人体动画中的基础问题．本文给出了以多面体组合来建立粗略人体，用多面体细分割来逼近真实人体曲面的方法，并在建模中考虑了人体的动态特性，为建立人体动画模型创造了条件．     

基于APDL桥梁参数化有限元分析方法研究

针对以往桥梁建模方法比较复杂与花费时间较长的缺点,以及有限元分析过程与建模过程脱节的技术问题,以混凝土斜拉桥A字型桥塔为例,提出一种基于桥塔点云模型边界特征约束的参数化建模方法,再运用参数化设计语言APDL编写程序,使得参数化在有限元分析过程中得以继承。此方法最大的特点是在点云模型特征边界约束参数关系基础上建立桥塔的有限元模型,然后根据桥塔实际受力荷载情况进行加载,最后计算模型并提取实验结果。实验结果表明,该方法能快速建立桥塔的参数化模型和提高有限元分析的有效性,进而可以得出桥塔结构的稳定性分析,为桥梁健康保护提供相应的依据。     

人体面部纹理贴图生成算法

在最近几年里,三维人体建模有了很大的发展,人脸视点无关纹理图对增强人脸的真实感起着关键的作用.本文阐述了常用的合成人体面部纹理贴图的方法,并进行了拓展,介绍了一种更加精确的算法.     

Matlab在三维人体及服装建模上的应用

在分析各种三维建模技术的基础上,提出三维人体及服装建模方法并进行了具体介绍。     

织物建模技术研究现状与进展

织物模拟技术是当前计算机图形学领域中的一个研究热点。该文首先综合介绍了织物建模技术的研究概况,其次分别从几何模型、物理模型和混合模型三个方面介绍了织物的建模方法;详细阐述了基于物理特性的建模方法,包括质点弹簧模型、粒子模型和有限元模型,并对物理模型的各个模型及其优缺点进行了分析和比较;最后对该领域存在的问题和技术发展趋势进行了分析和讨论。     

Bilevel Parameter Learning for Nonlocal Image Denoising Models

We propose a bilevel optimization approach for the estimation of parameters in nonlocal image denoising models. The parameters we consider are both the fidelity weight and weights within the kernel of the nonlocal operator. In both cases, we investigate the differentiability of the solution operator in function spaces and derive a first-order optimality system that characterizes local minima. For the numerical solution of the problems, we use a second-order trust-region algorithm in combination with a finite element discretization of the nonlocal denoising models and introduce a computational strategy for the solution of the resulting dense linear systems. Several experiments illustrate the applicability and effectiveness of our approach.

     

Multiple human tracking in high-density crowds

In this paper, we introduce a fully automatic algorithm to detect and track multiple humans in high-density crowds in the presence of extreme occlusion. Typical approaches such as background modeling and body part-based pedestrian detection fail when most of the scene is in motion and most body parts of most of the pedestrians are occluded. To overcome this problem, we integrate human detection and tracking into a single framework and introduce a confirmation-by-classification method for tracking that associates detections with tracks, tracks humans through occlusions, and eliminates false positive tracks. We use a Viola and Jones AdaBoost detection cascade, a particle filter for tracking, and color histograms for appearance modeling. To further reduce false detections due to dense features and shadows, we introduce a method for estimation and utilization of a 3D head plane that reduces false positives while preserving high detection rates. The algorithm learns the head plane from observations of human heads incrementally, without any a priori extrinsic camera calibration information, and only begins to utilize the head plane once confidence in the parameter estimates is sufficiently high. In an experimental evaluation, we show that confirmation-by-classification and head plane estimation together enable the construction of an excellent pedestrian tracker for dense crowds.     

Finite element approximations of nonlinear eigenvalue problems in quantum physics

In this paper, we study finite element approximations of a class of nonlinear eigenvalue problems arising from quantum physics. We derive both a priori and a posteriori finite element error estimates and obtain optimal convergence rates for both linear and quadratic finite element approximations. In particular, we analyze the convergence and complexity of an adaptive finite element method. In our analysis, we utilize certain relationship between the finite element eigenvalue problem and the associated finite element boundary value approximations. We also present several numerical examples in quantum physics that support our theory.     

基于几何造型的有限元网格的自适应生成

介绍一个基于几何造型系统的有限元分析的前处理系统。该系统可对几何造型的二维任意形体进行快速可靠的Ｄｅｌａｕｎａｙ三角剖分，提出网格自动生成的网格密度的控制和基于误差估计的自适应有限元网格生成算法，并给出了应用实例。     

Construction of higher‐order curl‐conforming finite elements and its assembly

Different choices are available when constructing vector finite element bases in real coordinates. In this communication, two different designs of higher‐order curl‐conforming basis functions are introduced and explained, showing the particularities of its assembly. Tetrahedra and hexahedra are used as element shapes to assess the effect of triangular and quadrilateral faces on the two considered constructions of basis functions. A comparison of their robustness in terms of the condition number of the finite element matrices for a number of distortions is included.     

人体几何建模方法综述

人体建模是计算机图形学与计算机视觉领域的重要研究课题,而人体几何建模则是人体建模的基础。人体几何建模技术发展至今,已经出现了大量的实现方法。回顾和总结了人体几何建模领域一些最新的研究成果,将其分为直接建模方法、2D图片识别方法、模板匹配方法、统计综合建模4大类,并且对人体几何建模方法的未来发展趋势进行了展望。     

Sharing attractions on the Net with VPark

We present a networked virtual environment (NVE) system and an attraction building system based on Windows NT that enables users to introduce their own scenario-based applications into a shared virtual environment. Our goal was to develop and integrate several modules into a system capable of animating realistic virtual humans in a real-time performance. This includes modeling and representing virtual humans with high realism and simulating human face and body movements in real time. Realism becomes quite important in NVEs, where the communication among participants is crucial for their sense of presence     

基于Petri 网的工业设计过程管理工作流建模研究

工业设计过程建模是产品设计过程管理研究的关键环节,直接影响着项目开发周 期和整体效益,但目前工业设计行业没有针对设计过程管理有效的建模技术及其系统。为实现 对工业设计企业设计过程动态性、结构性和有序性管理,在产品设计过程管理中引入面向过程 的组织管理与流程优化的工作流技术及Petri 网建模方法;然后根据对设计过程管理流程的研 究,构建了设计过程管理工作流程图;进而结合工作流技术、Petri 网过程建模方法和工业设计 过程管理流程提出工业设计过程管理的4 个阶段工作流建模方法：本体分析、元素提取、元素 概括、元素带入;最后,以工业设计过程管理建模领域为例构建了基于Petri 网的工业设计过程 管理工作流模型,在此基础上实现了工业设计过程管理原型系统。     

Image-based Virtual Exhibit and Its Extension to 3D

In this paper we introduce an image-based virtual exhibition system especially for clothing product.It can provide a powerful material substitution function,which is very useful for customization clothing-built.A novel color substitution algorithm and two texture morphing methods are designed to ensure realistic substitution result.To extend it to 3D,we need to do the model reconstruction based on photos.Thus we present an improved method for modeling human body.It deforms a generic model with shape details extracted from pictures to generate a new model.Our method begins with model image generation followed by silhouette extraction and segmentation.Then it builds a mapping between pixeis inside every pair of silhouette segments in the model image and in the picture.Our mapping algorithm is based on a slice space representation that conforms to the natural features of human body.     

A transparently scalable visualization architecture for exploring the universe

Modern astronomical instruments produce enormous amounts of three-dimensional data describing the physical Universe. The currently available data sets range from the solar system to nearby stars and portions of the Milky Way Galaxy, including the interstellar medium and some extrasolar planets, and extend out to include galaxies billions of light years away. Because of its gigantic scale and the fact that it is dominated by empty space, modeling and rendering the Universe is very different from modeling and rendering ordinary three-dimensional virtual worlds at human scales. Our purpose is to introduce a comprehensive approach to an architecture solving this visualization problem that encompasses the entire Universe while seeking to be as scale-neutral as possible. One key element is the representation of model-rendering procedures using power scaled coordinates (PSC), along with various PSC-based techniques that we have devised to generalize and optimize the conventional graphics framework to the scale domains of astronomical visualization. Employing this architecture, we have developed an assortment of scale-independent modeling and rendering methods for a large variety of astronomical models, and have demonstrated scale-insensitive interactive visualizations of the physical Universe covering scales ranging from human scale to the Earth, to the solar system, to the Milky Way Galaxy, and to the entire observable Universe