基于微分算子的三维人脸表情识别

基于拉普拉斯微分算子提出了一种用于三维人脸样本的表情识别方法。首先使用曲面变形的方法对三维人脸样本进行样本配准处理。然后基于拉普拉斯微分算子计算三维人脸的表情特征,并根据训练样本的特征向量集构建一个关于三维人脸表情的字典。最后使用稀疏表示方法对三维人脸表情进行识别分析。实验结果表明,该方法能够有效地提高三维人脸表情识别的准确率。     

基于HMM的单样本可变光照、姿态人脸识别

提出了一种基于HMM的单样本可变光照、姿态人脸识别算法.该算法首先利用人工配准的训练集对单张正面人脸输入图像与Candide3模型进行自动配准,在配准的基础上重建特定人脸三维模型.对重建模型进行各种角度的旋转可得到姿态不同的数字人脸,然后利用球面谐波基图像调整数字人脸的光照系数可产生光照不同的数字人脸.将产生的光照、姿态不同的数字人脸同原始样本图像一起作为训练数据,为每个用户建立其独立的人脸隐马尔可夫模型.将所提算法对现有人脸库进行识别,并与基于光照补偿和姿态校正的识别方法进行比较.结果显示,该算法能有效避免光照补偿、姿态校正方法因对某些光照、姿态校正不理想而造成的识别率低的情况,能更好地适应光照、姿态不同条件下的人脸识别.     

Lasso整脸形状回归的人脸配准算法

人脸配准是人脸识别、美化和面部表情分析等人脸相关应用的重要组成部分,这些应用通过人脸配准以精准定位人脸五官及面部轮廓特征点.在整脸形状回归的人脸配准框架基础上,使用Lasso回归来解决人脸配准问题,提出基于Lasso的整脸回归人脸配准算法.首先对人脸配准过程中的回归系数施加L1模惩罚,以在不牺牲效果的基础上减少模型大小;然后提出人脸变换比例调整方法,在回归过程中使用人脸变换比例对特征点位置进行调整,用于解决小规模样本条件下不同尺度样本相互干扰的问题.在相关数据集上的实验结果表明,该算法配准精确度高,可以达到实时的速度,且适用于不同姿态下的人脸配准问题.     

基于精确主轴分析及ICP的三维人脸配准

论文提出了一种基于精确主轴分析的三维人脸预配准方法。利用人脸在其主轴坐标系下均呈相同的正面姿态的特点,通过将标准模型和待配准模型都转换到其主轴坐标系下,来实现三维人脸模型的预配准,然后使用ICP方法进行精确配准。实验证明,所提方法具有良好的姿态鲁棒性和噪声鲁棒性。     

创建中国人三维人脸库关键技术研究

通过CyberWare人脸专用扫描仪获取高分辨率的彩色三维人脸来构建中国人三维人脸数据库．创建三维人脸数据库时,要对原始三维人脸数据进行预处理,并通过规格化将三维人脸表示为统一的标准形式．规格化的关键是要建立三维人脸数据基于特征的稠密对应,这是图形学和计算机视觉中的难点问题,目前使用光流方法建立的对应效果并不理想,因此提出了基于网格重采样的计算方法,取得了良好的对应效果．     

变形图驱动的人体与脸部网格模板拟合系统

为了建立统一的人体模型数据库/人脸模型数据库,实现了一个用标准三维人体/人脸网格模型拟合扫描数据的系统.该系统为人体模型构建特征点候选区域,用马尔可夫网络对候选区域进行概率预测得到人体特征点的位置;对于人脸模型,采用基于回归树的算法在多幅不同角度的人脸图像上分别检测其二维特征点,融合得到准确的三维特征点位置;得到特征点后,使用相似变换对标准模板和扫描模型的位置朝向以及尺度进行统一;通过特征点引导的变形图算法对标准模板和扫描模型的形状和姿态进行粗配准;最后使用基于稠密点对应的顶点仿射变换拟合得到变形后的标准模板.对CAESAR数据集中的人体模型以及扫描得到的人体和人脸模型均进行了拟合,实验结果表明,该系统能够精确地捕捉扫描数据的几何形状.     

基于闪烁光照的视频回放攻击检测方法

提出了一种新的基于光照的人脸识别系统回放攻击检测方法。使用普通视频采集设备采集的侧向闪烁光照条件下人脸视频,通过对原始视频信号应用运动模板算法,进而得到原始视频信号对应的MEI(Motion-energy images)图像序列。以此依据,对被测试样本为三维人脸,还是屏幕人脸视频回放加以分类识别。     

改进的统计模型三维人脸特征点标定算法框架

自动三维人脸特征点标定是计算机视觉领域的研究热点,其广泛应用于人脸识别,人脸模型配准,表情识别,脸部动画等领域。通过对三维人脸样本统计建模,采用遗传算法对待匹配模型的生成数目进行参数优化,利用模型相似性匹配方法及其映射关系对三维人脸特征点进行自动标定。首先,对三维人脸数据预处理,然后对其统计建模并通过模型形变得到有映射关系的基准模型和待匹配模型。利用遗传算法对待匹配模型中的待匹配模型生成数目参数进行优化,生成与之对应的待匹配模型数;接着计算待测模型与待匹配模型的相似度。最后,利用模型相似度和模型映射关系,间接得到待测模型的特征点。实验结果表明,提出的算法是可行的,能够在一定程度上提高原有算法的效率。该算法可以自动标定三维人脸模型的特征点,当距离阈值为10像素时,39个三维人脸特征点定位的准确率都可以达到100%,并有效解决了传统方法中三维人脸模型平滑区域特征点精度不高的问题。     

基于三维采样点集的人脸识别

采用基于整体轮廓的提取方法来对三维人脸点集进行重采样表征人脸。首先将三维人脸区域的点集校正到统一的姿态坐标系,并将其转换为深度图,之后计算深度图的一阶和二阶梯度,并设定阈值提取出边界曲线,再找出二维梯度图的边界曲线所对应的三维空间中的曲线点集用来表征人脸,最后用D-ICP算法进行配准并进行相似度测量。在欧洲人脸数据库GAVAB3D中进行了测试,实验结果表明该方法简便有效。     

一种应用于大角度变换点云的配准方法

针对传统配准法不能很好解决大角度变换点云的配准这一问题,提出一种基于精 确对应特征点对及其 K 邻域点云的配准方法。首先分别计算两组点云的 FPFH 值,根据特征值 建立点云间的对应关系;然后通过 RANSAC 滤除其中错误的匹配点对,得到相对精确的特征点 对集合;之后通过 KD-tree 搜索的方式分别找出特征点对 R 半径邻域内的点,应用 ICP 算法得 到两部分点云的最优收敛;最后将计算得到的相对位置关系应用到原始点云上得到配准结果。 通过对斯坦福大学点云库中 Dragon、Happy Buddha 模型以及 Kinect 采集的石膏像数据进行配 准和比较,实验表明该方法能够有效解决大角度变换点云的配准问题,是一种具有高精度和高 鲁棒性的三维点云配准方法。     

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。     

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.     

Editorial: Special issue on recent advances in hybrid control theory and applications

正The demands of a rapidly advancing technology for faster and more accurate controllers have always had a strong influence on the progress of automatic control theory.In recent years control problems have been arising with increasing frequency in widely different areas,which cannot be addressed using conventional control techniques.The principal reason for this is the fact that a highly competitive economy is forcing systems to operate in regimes where     

Information for Authors

正Aim The Journals of Zhejiang University-SCIENCE(A/B/C)areedited by the international board of distinguished Chinese andforeign scientists,and are aimed to present the latest devel-opments and achievements in scientific research in China andoverseas to the world’s scientific circles,especially to stimulateand promote academic exchange between Chinese and for-eign scientists everywhere.     

Enhancing a leaf radiative transfer model to estimate concentrations and in vivo specific absorption coefficients of total carotenoids and chlorophylls a and b from single-needle reflectance and transmittance

The relative concentrations of different pigments within a leaf have significant physiological and spectral consequences. Photosynthesis, light use efficiency, mass and energy exchange, and stress response are dependent on relationships among an ensemble of pigments. This ensemble also determines the visible characteristics of a leaf, which can be measured remotely and used to quantify leaf biochemistry and structure. But current remote sensing approaches are limited in their ability to resolve individual pigments. This paper focuses on the incorporation of three pigments—chlorophyll a, chlorophyll b, and total carotenoids—into the LIBERTY leaf radiative transfer model to better understand relationships between leaf biochemical, biophysical, and spectral properties.Pinus ponderosa and Pinus jeffreyi needles were collected from three sites in the California Sierra Nevada. Hemispheric single-leaf visible reflectance and transmittance and concentrations of chlorophylls a and b and total carotenoids of fresh needles were measured. These data were input to the enhanced LIBERTY model to estimate optical and biochemical properties of pine needles. The enhanced model successfully estimated reflectance (RMSE = 0.0255, BIAS = 0.00477, RMS%E = 16.7%), had variable success estimating transmittance (RMSE = 0.0442, BIAS = 0.0294, RMS%E = 181%), and generated very good estimates of carotenoid concentrations (RMSE = 2.48 µg/cm², BIAS = 0.143 µg/cm², RMS%E = 20.4%), good estimates of chlorophyll a concentrations (RMSE = 10.7 µg/cm², BIAS = − 0.992 µg/cm², RMS%E = 21.1%), and fair estimates of chlorophyll b concentrations (RMSE = 7.49 µg/cm², BIAS = − 2.12 µg/cm², RMS%E = 43.7%). Overall root mean squared errors of reflectance, transmittance, and pigment concentration estimates were lower for the three-pigment model than for the single-pigment model. The algorithm to estimate three in vivo specific absorption coefficients is robust, although estimated values are distorted by inconsistencies in model biophysics. The capacity to invert the model from single-leaf reflectance and transmittance was added to the model so it could be coupled with vegetation canopy models to estimate canopy biochemistry from remotely sensed data.     

Mr. Twinn’s bombes

This article discusses the history and design of the special versions of the bombe key-finding machines used by Britain’s Government Code & Cypher School (GC&CS) during World War II to attack the Enigma traffic of the Abwehr (the German military intelligence service). These special bombes were based on the design of their more numerous counterparts used against the traffic of the German armed services, but differed from them in important ways that highlight the adaptability of the British bombe design, and the power and flexibility of the diagonal board. Also discussed are the changes in the Abwehr indicating system that drove the development of these machines, the ingenious ways in which they were used, and some related developments involving the bombes used by the U.S. Navy’s cryptanalytic unit (OP-20-G).