EM-GPA: Generalized Procrustes analysis with hidden variables for 3D shape modeling

Aligning shapes is essential in many computer vision problems and generalized Procrustes analysis (GPA) is one of the most popular algorithms to align shapes. However, if some of the shape data are missing, GPA cannot be applied. In this paper, we propose EM-GPA, which extends GPA to handle shapes with hidden (missing) variables by using the expectation-maximization (EM) algorithm. For example, 2D shapes can be considered as 3D shapes with missing depth information due to the projection of 3D shapes into the image plane. For a set of 2D shapes, EM-GPA finds scales, rotations and 3D shapes along with their mean and covariance matrix for 3D shape modeling. A distinctive characteristic of EM-GPA is that it does not enforce any rank constraint often appeared in other work and instead uses GPA constraints to resolve the ambiguity in finding scales, rotations, and 3D shapes. The experimental results show that EM-GPA can recover depth information accurately even when the noise level is high and there are a large number of missing variables. By using the images from the FRGC database, we show that EM-GPA can successfully align 2D shapes by taking the missing information into consideration. We also demonstrate that the 3D mean shape and its covariance matrix are accurately estimated. As an application of EM-GPA, we construct a 2D + 3D AAM (active appearance model) using the 3D shapes obtained by EM-GPA, and it gives a similar success rate in model fitting compared to the method using real 3D shapes. EM-GPA is not limited to the case of missing depth information, but it can be easily extended to more general cases.     

Messages from the Eagle

ABSTRACT

Each year Dacus Library teaches library use to over a thousand freshmen in introductory Writing classes. In the summer of 2000, two reference librarians undertook a revision of the basic methodology of teaching library use to freshmen. This change was necessitated by staff shortages, coupled with increasing enrollment. The resulting virtual tour, which was introduced in fall 2000, combined an existing audio-tape tour with one hour of classroom instruction. The university's mascot, an eagle, was used to lead the students on a tour of all three floors of Dacus Library, with explanations of each location pictured. In addition, the eagle was used to describe and explain the online catalog. The new virtual tour, while still a work in progress, is considered to be a success by students, library faculty and staff, and Writing instruction faculty. You can visit the Dacus Library tour at www.winthrop.edu/dacus/About/Tapetour/Exercises/assignment2.htm.     

Exploring Virtual Librarianship: Second Life Library 2.0

ABSTRACT

In April 2006, Alliance Library System and Online Programming for All Libraries partnered to start the Second Life Library 2.0 in the online world Second Life and in August 2006 purchased an island on the Teen grid of Teen Second Life. Second Life is a virtual world, a descendant of multiplayer online games. Educational institutions have recently been drawn into Second Life's robust economy and vibrant cultural life. The Second Life Library 2.0 works with librarians from around the world and with other educational partners such as TechSoup, WorldBridges, and the New Media Consortium. Second Life Library 2.0 provides “traditional” library services such as ready reference, book discussions, and search assistance, but, at heart, it explores what it means to be a virtual library in a virtual world.     

基于MQP模型的电离图参数反演解析算法研究

针对现今普遍采用的偏导迭代电离图反演算法存在的求解依赖于初值选择的不足,给出了一种初值选择准则,保证了该算法的收敛性。同时,利用该准则,以及在对电离图虚高表达式进行合理近似的基础上,提出了一种新的电离图参数反演算法,该方法实现电离图参数反演的解析计算,较偏导迭代法计算量大大减少,更好满足工程实时性要求。     

移动P2P文件共享系统中基于用户偏好的激励机制

提出一种基于用户偏好的激励机制,鼓励用户通过提供共享文件和转发操作为系统做出贡献。IMBPC结合了虚拟价格机制和预期文件传输延时,基于用户对价格和延时的偏好度来选择最合适的节点进行文件下载。通过设置模拟实同仅通过虚拟价格机制来激励用户做出贡献的策略进行比较,显示应用IMBPC策略的系统,节点的贡献积极性明显增加。     

飞行模拟器虚拟仪表设计

阐述某型飞机飞行模拟器仪表仿真系统的设计方案,给出在Visual C++6.0下基于OpenGL的虚拟仪表的绘制方法。实践证明,基于OpenGL的虚拟仪表建模形象逼真,代码的可重用性好、效率高、扩展性强,在通用性和模块化方面具有良好的特性。     

Proteus仿真在单片机教学中的应用

Proteus仿真软件只要利用PC机就可以完成单片机及其外围电路的协同仿真,近年来被广泛应用到单片机教学当中。学生基于Proteus平台学习单片机知识,更直观,能够激发学生的学习兴趣,提高学生的综合设计能力,有利于提高教学效果。     

虚拟机技术在计算机课程教学中的应用

当前很多学校都开设有计算机专业,然而由于资金缺乏,不少学校没有建立配套完善的专业实训室,而正常的教学机房又不允许安装软件,导致很多实验无法完成,教学效果达不到预期的目标。笔者经过几学期的摸索,提出了利用VMware虚拟机技术,在真实的计算机上安装虚拟机,可以在虚拟机上做各种实验,模拟真实网络服务环境。解决网络课程教学对于网络环境的要求问题。本文主要阐述虚拟机技术在计算机及网络教学中具有经济、实用、灵活的特点,供大家借鉴。     

浅谈人机工程分析软件在虚拟制造中的应用

在当今经济全球化、贸易自由化和社会信息化的形势下,制造业的经营战略发生了很大变化,在30-60年代企业追求的是规模效益,70年代更加重视降低生产成本,进入90年代新产品开发厦交货期成为竞争的焦点。由此产生了多种多样的制造哲理,如：精益生产、并行工程、敏捷制造和虚拟制造等,它们各有侧重,从不同角度研究如何增强企业的竞争力。而虚拟制造技术是制造技术与仿真技术相结合的产物。     

企业网安全技术的分析与研究

随着企业信息化的不断发展,企业网的安全越来越受到各个企业的关注。本文分析了企业网当前存在的主要安全隐患,对企业网安全技术进行研究,并结合企业网络安全需求,从技术方面出发提出了解决企业网络安全的策略,对提高企业网络安全具有一定的技术指导作用。