基于主动视觉的运动目标检测跟踪方法

研究主动视觉运动目标检测跟踪系统。针对图像目标跟踪多为非连续动态过程,准确性差,通过混合高斯法建立背景模型,采用背景差分法,利用最大类间方差算法确定阈值,检测分割出运动目标,提出一种结合SURF算法的带宽自适应均值漂移跟踪算法实现目标跟踪,使用线程并行控制摄像机运动,确保跟踪目标在图像序列中的合适尺寸。实验表明,改进系统能够实现对场景中运动目标的准确检测,稳定跟踪,并能到达实时应用的要求。     

基于SURF的压缩跟踪算法研究

目标跟踪技术作为机器视觉领域中的基础,有着广泛的应用,但其仍然存在许多问题。为了解决目标在光照变化和快速移动场景下跟踪漂移的问题,提出了基于SURF的压缩跟踪算法。首先选择跟踪目标并提取SURF特征,其次采用压缩感知理论对SURF高维特征降维,来减少特征描述的维数和计算时间,最后筛选压缩后的样本特征并训练分类器,来实现对多种复杂场景下目标实时准确跟踪。通过实验与传统的SURF算法和Compressive Tracking(CT)算法的对比,证明该算法不仅大大减少了目标在跟踪的过程中的计算量,其跟踪的实时性和准确性相较于CT算法和SURF算法都有所提高。     

基于改进的颜色和SURF特征的粒子滤波目标跟踪

针对视频中运动目标的准确跟踪问题,提出了一种改进的颜色直方图特征和SURF特征的粒子滤波跟踪算法。采用SURF算法提取特征点,利用分层迭代的KLT算法对特征点进行稳定跟踪。将SURF特征与改进的视觉显著性颜色特征进行乘性融合,作为粒子滤波的观测概率。针对跟踪过程中SURF匹配数下降和不稳定的现象,设计了SURF特征模板集的更新策略。与传统特征的跟踪进行多组对比实验,其结果证明了该方法对光照和遮挡具有很好的鲁棒性,对目标跟踪的准确率更高。     

改进的SURF算法及其在目标跟踪中的应用

SURF特征描述子在目标跟踪中得到了有效应用.针对SURF特征描述子运算复杂,难于在嵌入式系统中实时实现的问题,提出了一种改进的SURF特征描述子.对SURF特征描述子的生成过程进行了改进,利用三角特征和对角线特征设计了改进的SURF特征描述子.对不同变化情况下的图片进行了特征点匹配实验,对其性能进行了验证和分析;在DSP中对所提改进SURF特征描述子的快速实现进行了验证,在实验条件下,改进的SURF特征描述子在DSP中的运算速度达到了28f/s,比改进前提高了约47％.最后,基于SURF特征点匹配,设计了目标匹配跟踪策略,对改进SURF特征描述子在目标跟踪中的有效性进行了验证.     

基于SURF和CamShift的物体跟踪方法

CamShift算法是一种常用的跟踪算法,但是它只利用颜色特征来进行目标跟踪,当背景颜色与跟踪目标的颜色相似时会出现跟踪失败的情况。结合SURF设计了一种基于SURF和CamShift算法的创新的跟踪方法。利用反馈机制计算CamShift跟踪窗口与初始窗口的特征相似度以及SURF跟踪窗口与初始窗口的色彩相似度;同时抑制大的位移变化,为两种跟踪算法动态分配位移的权重,以实现对物体的跟踪。测试实验表明,该跟踪方法对不同的物体、在不同的环境下有较好的效果。     

基于SURF的增强现实标识物跟踪注册

针对基于标识物的增强现实跟踪注册方法对复杂环境的适应能力和鲁棒性的不足,提出一种用SURF实现标识物跟踪注册的改进算法。用SURF对平面标识物的特征点进行检测与描述,采用K-means算法对检测出的标识物特征点集合进行聚类分析得到其聚类中心,结合对视频图像中标识物的阈值分割与连通域分析,以聚类中心构建标识物的SURF特征点坐标系,通过矩阵变换实现标识物的跟踪注册。实验结果表明,该算法的增强现实系统具备较好的鲁棒性、稳定性和实时性。     

一种基于改进CAMshift的多特征跟踪算法

针对传统CAMshift跟踪算法在复杂环境中跟踪效果不理想的问题,论文提出融入基于纹理特征的SURF算法与改进CAMshift算法形成多特征融合跟踪算法。通过基于色调分量H和饱和度分量S联合生成目标直方图模板,利用完整的目标颜色信息特征增强算法对复杂环境的适应能力。为进一步提高算法的鲁棒性,利用SURF算法实现跟踪目标的重定位,克服了复杂环境下丢失目标后跟踪问题。实验证明,论文提出的多特征融合算法在保持理想的鲁棒性和准确性的同时,也提高了跟踪的实时性。     

在线多类别逐点式多目标跟踪与分割

现有基于深度学习的多目标跟踪算法大多利用目标检测任务预测的边界框跟踪目标,当目标间存在遮挡时,边界框会产生重叠进而影响跟踪准确度,针对这个问题,提出了一种在线多类别逐点式多目标跟踪与分割（category-free point-wise multi-object tracking and segmentation,CPMOTS）算法。该算法摒弃了边界框的目标表征方式,利用实例分割的像素级掩码表征目标进行跟踪,网络采用并行结构同时分割与跟踪多类别目标,并保证了运行效率,这在真实场景中有很强的实用性。CPMOTS首先利用实例分割网络得到实例分割掩码,对其采样得到无序点集;然后将点集的特征输入跟踪网络得到判别性的实例级嵌入向量;最后将该嵌入向量通过直观高效的注意力模块以显式建模其通道间的依赖关系,自适应学习每个特征通道的重要程度,依照这个重要程度选择性地强化有用的特征,抑制无用的特征,实现通道特征重标定,从而提高算法的性能。在多目标跟踪与分割基准数据集KITTI MOTS的实验表明,CPMOTS跟踪的精度优于大部分其他对比方法,并达到了16 frame/s的近实时速度。     

基于SURF算法的人脸跟踪技术研究

人脸检测与跟踪技术是计算机视觉领域研究课题之一,在军事及民用领域应用广泛.在目标检测算法中,基于特征的方法具有压缩信息量、执行速度快、精度高等优点,成为近年来目标检测领域的研究热点.SIFT算法便是其中之一,但传统的SIFT算法应用于人脸检测过程中有数据量大、计算耗时长,提出了一种基于SURF算法的人脸检测方法,阐述了SURF算法的基本原理,并首先将SURF算法应用于人脸特征检测与跟踪,阐述了人脸跟踪系统设计方法,使用OpenCV技术实现了基于SURF算法的人脸跟踪验证系统.试验结果表明,基于SURF算法的人脸跟踪系统匹配识别效果较好,实时性较好、具有较好鲁棒性.     

一种有效的实时人群计数方法

对固定镜头下视频序列中运动人体的检测和跟踪方法进行研究,利用灰度图像差分双向投影信息检测人体目标,提出一种基于统计运动区域几何特征固定比例的分割算法,使用最近邻匹配方法对人体进行跟踪。完整地实现了一个有效的实时人群计数系统。大量室内和室外场景实验结果表明,该算法具有很好的实时性(每秒处理25帧~30帧且可并行处理4路视频)、对光照变化的鲁棒性以及对稀疏人群检测精度高等特点。     

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).