基于GPU的实时光线投射算法

介绍了一种基于GPU（可编程图形处理单元）的快速实时光线投射算法。为满足大规模体数据集的绘制要求,利用当前GPU的新特性,直接将体数据作为纹理载入显存,采用预积分分类方法在GPU中对体数据进行重采样和分类,避免了计算机主内存与GPU纹理内存之间数据交换的瓶颈问题;利用硬件支持的三维纹理和片元着色器,实时计算每个体素的梯度,实现高质量的光照,保证高质量的图像绘制效果。实验结果表明该方法在医学三维数据场可视化中,能够实时、高效地生成高质量的交互式体可视化图像。     

基于Web Service的分布式并行体绘制研究

目前,随着可视化要处理的数据量变得越来越大以及可视化操作变得越来越复杂,基于网格或Web服务的分布式可视化技术得到了快速发展.在体绘制领域,体数据的大规模增长,迫切期待提高计算设备的处理能力.基于Web服务的分布式技术的快速发展为体绘制的研究提供了新的途径.为了便于Web服务技术在体绘制中的应用的,该文提出了一种基于W...     

基于满二叉树分块策略的大规模数据场纹理映射体绘制算法

针对纹理映射体绘制物理内存空间的限制,本文提出一种可在通用图形硬件上完成大规模数据场实时体绘制的有效方法.该方法基于满二叉树纹理分块策略,利用GPU着色器可编程性,将纹理数据制作为一个一维传递函数查找表和一个规模等同于体数据场的动态纹理工作集,有效提高了大规模数据场体绘制的实时性.动态纹理工作集使用抽象分块与继承关系管...     

基于PC硬件的大规模数据场快速可视化方法

科学可视化技术在众多领域具有十分广泛的应用,然而直接体绘制技术却有着计算量大、计算时间长的缺点,在普通的PC机上很难实现对大规模数据的实时交互绘制。目前的三维可视化系统通常需要架构在高端的图形工作站或转用计算机上。随着计算机软硬件技术的发展,普通的PC机图形处理器GPU(Graphic Processing Unit)具有了可编程功能。正是借助GPU的可编程功能及其强大的并行处理能力,研究并实现了一种基于普通PC硬件的体会之方法。最后应用该方法对工业、医学等体数据进行可视化,结果证明该方法可以在普通PC上实现较大规模数据的快速可视化。     

基于纹理的Fluent数据场可视化

为了高效可视化热工计算得到的数据场，由于采用传统的面绘制方法不能准确反映数据场中各种因素的相互关系，使研究人员难以把握数据场的全局。而采用体绘制方法可视化数据场，只能从数据场的外部观察模型，无法漫游到模型的内部观察数据场的细节。故本文采用基于颜色映射的纹理贴图方法即首先把空间三维数据场转化为一系列二维数据集，然后采用二维可视化方法中的颜色映射法来生成纹理图，最后把生成的纹理图贴到模型内壁上。该算法是高效可行的，并已得到验证。     

光线投射算法中重采样的设计和实现

体绘制技术在医学成像和科学可视化领域有着极为广泛的应用，但由于其巨大的计算开销，限制了其实时动态体绘制的应用，因此许多研究人员致力于静态体绘制加速算法的研究，为了提高体绘制速度。分析了三维规则数据场重采样的原理。光线投射算法中对3D数据场重采样的实现方法；根据具体重建对象，提出了在3D数据场重采样中采用球形包围盒的方法，给出了人体头部和眼球的三维可视化结果，实验表明：这种算法能有效地减少重采样的计算量，并使求交计算更加简单。     

基于Mipmap的大规模地形绘制算法与仿真

研究大规模地形与纹理数据动态可视化算法与仿真问题。针对大规模地形与纹理数据动态可视化实时显示难题,提出一种基于Mipmap的大规模地形动态绘制算法,实现模型数据库组织与管理的高效性、场景调度的实时性,以北京市地形数据为仿真模型,实现大规模地形与纹理数据动态可视化算法与实时仿真。上述算法在Mipmap技术的基础上,首先利用双线性内插算法把离散的原始数据生成规则网格DEM,然后采用四叉树结构的LOD算法简化海量地形和纹理数据,最后使用四队列分页调度、基于视域的LRU算法释放内存、多线程并行处理的场景优化策略来进行动态调度和绘制。结合OSG和Open GL渲染引擎,将基于Mipmap的大规模地形绘制算法应用在北京市地形绘制中,仿真结果表明,上述算法比传统的CLOD地形瓦片绘制算法,具有更快的渲染绘制速率,并且能够快速绘制北京市地形数据和在不同场景下进行快速浏览。     

大规模数字高程模型的可视化研究

根据细节层次模型（LOD）的设计思想,提出了大规模数字高程模型的数据组织和可视化方法。该方法在数据分页算法和细节层次模型相结合的基础上,采用视区计算和边界融合算法,实现了地形的快速绘制。实验证明该方法实现了高性能绘制大规模数字高程模型。     

基于GPU的三维地震数据场体绘制方法

体绘制技术是计算可视化研究和应用热点之一。在对三维数据体进行形式化定义基础上,讨论光线投射算法中数据体划分,重采样计算以及图像合成的原理和方法。利用着色器进行重采样和图像合成运算,实现体绘制的GPU加速。将GPU加速的光线投射体绘制方法应用于地震数据解释,分别实现地震数据的灰度和伪彩色样式可视化,并通过转换函数,凸显出地震数据场的层位特征,克服了地震数据剖面、切片以及三维面绘制图像的局限性。     

基于图象的交互绘制和数据压缩

体数据的绘制速度是交互可视化的瓶颈。将基于图象的绘制方法和传统的体绘制方法相结合,提出了一个新的基于图象的快速图形图象绘制系统,大大提高了体数据交互可视化的速度。该方法首先用传统的体绘制方法得到一列采样图象,然后根据图象间象素的冗合性,通过Ｗａｒｐｉｎｇ变换压缩数据,由压缩后的数据Ｗａｒｐｉｎｇ生成任意视点的视图。为了进一步提高计算速度,给出了递推Ｗａｒｐｉｎｇ变换计算流程。     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

基于QTE的蒙古文显示机制研究与实现

蒙古语言是中国蒙古族使用的通用语言,由于蒙古文区别于其他文字的书写方式和其自身变形机制等特点,在很多通用的文字处理引擎中都不被支持。在嵌入式产品开发与应用领域中Linux加QTE已经成为流行方式。该文给出了一种在QTE环境上实现基于标准Unicode的蒙古文点阵显示和变形算法, 并自定义了支持蒙古文的QTE组件,扩展了QTE功能,为在Linux加QTE方式的嵌入式体系结构中处理蒙古文提供了一种解决方法。