基于环境映照自动对齐的高质量虚实融合技术

要实现高品质的增强现实效果需要解决虚拟物体与现实场景的光照一致性问题.虽然采用HDR技术能获取场景的环境映照,但需要解决所获取的光照环境信息与真实场景的对齐问题.为此提出一种基于特征自动匹配的环境映照对齐方法.首先采用Affine-SIFT算法和随机抽样一致性算法对环境映照和拍摄场景进行特征匹配并优化匹配结果,然后利用基于运动推断结构的摄像机定标算法求得匹配对的三维位置,从而计算出环境映照与真实场景的对应关系,实现了二者的自动对齐.基于该技术搭建的高真实感实时虚实融合系统采用基于关键帧的相机跟踪技术,可以实时地将虚拟物体注册到拍摄的视频场景里,并允许对其进行实时的交互编辑.在渲染时有效地利用了自动对齐后的光照环境信息,采用重要性采样算法和阴影映射技术实现了实时的高质量渲染.实验结果表明,所搭建的增强现实系统很好地解决了实时虚实融合中的几何一致性和光照一致性问题.     

基于图像分解的光照估计算法

增强现实技术的目的在于将计算机生成的虚拟物体叠加到真实场景中。实现良好的虚实融合需要对场景光照进行估算,针对高光场景,利用场景中的不同反射光信息对场景进行有效的光照估计,首先通过基于像素聚类方法的图像分解对图像进行反射光的分解,得到漫反射图和镜面反射图,对漫反射图进行进一步的本征图像分解,得到反照率图和阴影图;之后结合分解结果和场景深度对输入图像的光照信息进行计算;最后使用全局光照模型对虚拟物体进行渲染,可以得到虚实场景高度融合的光照效果。     

虚拟航空场景中阴影消除的仿真研究

研究虚拟航空场景真实感仿真问题.真实航空视野场景中,航空视野兴趣区存在较大的随机性和不定性的物体.物体会造成场景中出现随机性遮挡干扰.传统的虚拟建模技术很难对上述随机物体做出预判,进而造成虚拟建模像素意外遮挡,虚拟场景中形成较大阴影,影响了航空视野虚拟场景的真实效果.为了解决上述问题,提出一种HSV空间内,虚拟航空视野中的阴影去除算法,通过卡尔曼滤波对航空视觉图像进行实时跟踪,计算产生的阴影部分面积,利用合理的HVS空间内的像素阀值计算消除航空视觉虚拟现实中的阴影.后期的仿真结果证明,改进算法能够有效的消除运动状态下的视觉阴影,算法的精度较高.     

基于色度一致性的室外场景光照参数估计

针对不同天气情况下在同一太阳方位拍摄的室外场景图像,提出了一种基于色度一致性的光照参数估计算法。该算法基于太阳光与天空光基图像分解理论,利用色度一致性这一约束条件求解太阳光和天空光的光照系数;并利用光照色度校正模型对基图像进行光照色度校正,从而得到更准确的光照参数。 实验结果表明,所提算法是有效且正确的,根据基图像和光照系数可以准确重构原图像,从而实现虚拟物体与真实场景的无缝融合。     

基于增强现实技术的景观规划系统

增强现实是把计算机产生的虚拟物体或其他信息合成到用户看到的真实世界中的一种技术，利用增强现实技术，设计人员能够有效地进行建筑布局的规划和设计，本文介绍了一个典型的增强现实系统-景观规划系统的实现，针对合成虚拟景物和真实场景过程中需要解决的几何一致性和光照一致性问题，采用了局部三维重建和交互的相机定标技术来实现几何一致性；对于光照一致性，则采用了光照交互指定和自动恢复相结合的方法，同时还考虑了虚拟物体投射的阴影，针对不同场景的实际应用，依据系统生成的结果合成图象，设计人员能够比较有效地完成对景观规划结果的直观评估。     

基于图像与几何混合的纺织品真实感绘制

纺织品的真实感绘制是虚拟服装与试衣系统研究中的一项关键技术.采用图像图形结合的方法,提出了一种新的纺织品真实感绘制算法.对于场景中的实景,从原始照片中提取光照参数,将它与新纹理图相融合,利用色彩一致性理论和表面反射模型,达到类似于照片的展示效果.基于同样的理论研究,还可以模拟在纺织品的某些反射特性有所变化时的效果.对于原来场景中不存在的虚景,把用计算机生成的三维虚拟物体叠加到从真实世界获取的场景画面,应用实景提取的光照参数,并使用相应的光照模型对三维物体进行光照重计算.从而达到很好的虚实融合效果.     

用于增强现实的光照估计研究综述

增强现实技术将计算机生成的虚拟物体实时叠加到用户周围的真实场景中,虚拟物体与真实环境拥有一致的光照效果是该技术的难点之一.光照一致性研究包括光照估计、材质表面反射属性估计以及真实感渲染等内容,其中光照估计是光照一致性的先决条件,结合材质表面反射属性可以保证虚实物体一致的光照渲染效果.文中概述了增强现实中光照一致性研究的最新进展,通过分析现有技术的优缺点阐述了当前光照估计研究所面临的主要挑战,同时展望了该领域未来的发展方向.     

复杂环境光源下虚实融合光照实时计算

在互动电子游戏、增强现实等对实时计算要求很高的交互式图形应用中,大量使用复杂环境光源对虚拟物体进行照明,使其和真实场景的光照一致,虚实融合.提出了用Cook Torrance光照模型进行虚实场景的光照计算;利用球面调和基函数的方法,实时地计算高动态范围环境映射光照系数,得到高动态范围环境映射的二次多项式表达形式,在着色器计算该式得到漫反射分量;通过环境映射技术对镜面反射进行模拟,全部光照计算在GPU中完成.实验结果表明,该方法在动态变化的复杂环境光源下,完成对虚拟物体光照实时计算,绘制速度每秒30帧以上,绘制结果具有较强的真实感.     

利用平面虚拟点光源的素描图像绘制

素描画是一种常见的艺术形式,它通过单色线条来表现直观世界中的事物,而能够体现场景层次的高光和阴影则是表现的重点.艺术家经常会对场景的光影进行艺术化的夸张,这种艺术夸张会更好地表现作品主题.首先提出一种二维图像平面的虚拟点光源位置估计算法,根据输入的真实图像的距离场和亮度场,计算虚拟点光源位置,使其对原图像的亮度梯度影响最小,即最符合原场景中的光照方向.然后提出基于二维虚拟点光源的阴影增强算法,加强了真实图像中的明暗对比,因此能够在最终的素描结果中表现出光影效果.使用该方法生成的素描画,在物体边界处具有更好的明暗对比,从而使得最终绘制图像更具有素描画的光影增强特点.     

基于增强现实的虚拟实景空间的研究与实现

增强现实可以把计算机产生的虚拟物体或其他信息合成到用户看到的真实场景中．本文将增强现实技术与基于图像的绘制技术有机的结合起来，研究并实现了一个基于增强现实技术的虚拟实景空间系统．首先介绍了虚拟实景空间的构造，然后着重探讨了虚拟物体与实景空间的合成方法，主要解决合成中的几何一致性和光照一致性问题。     

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。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.