自适应权重更新的轻量级视频目标分割算法

目的 针对现有视频目标分割（video object segmentation,VOS）算法不能自适应进行样本权重更新,以及使用过多的冗余特征信息导致不必要的空间与时间消耗等问题,提出一种自适应权重更新的轻量级视频目标分割算法。方法 首先,为建立一个具有较强目标判别性的算法模型,所提算法根据提取特征的表征质量,自适应地赋予特征相应的权重;其次,为了去除冗余信息,提高算法的运行速度,通过优化信息存储策略,构建了一个轻量级的记忆模块。结果 实验结果表明,在公开数据集DAVIS2016 （densely annotated video segmentation）和DAVIS2017上,本文算法的区域相似度与轮廓准确度的均值J&F分别达到了85.8%和78.3%,与对比的视频目标分割算法相比具有明显的优势。结论 通过合理且无冗余的历史帧信息利用方式,提升了算法对于目标建模的泛化能力,使目标掩码质量更高。     

多帧时空注意力引导的半监督视频分割

目的 传统的半监督视频分割多是基于光流的方法建模关键帧与当前帧之间的特征关联。而光流法在使用过程中容易因遮挡、特殊纹理等情况产生错误,从而导致多帧融合存在问题。为了更好地融合多帧特征,本文提取第1帧的外观特征信息与邻近关键帧的位置信息,通过Transformer和改进的PAN（path aggregation network）模块进行特征融合,从而基于多帧时空注意力学习并融合多帧的特征。方法 多帧时空注意力引导的半监督视频分割方法由视频预处理（即外观特征提取网络和当前帧特征提取网络）以及基于Transformer和改进的PAN模块的特征融合两部分构成。具体包括以下步骤：构建一个外观信息特征提取网络,用于提取第1帧图像的外观信息;构建一个当前帧特征提取网络,通过Transformer模块对当前帧与第1帧的特征进行融合,使用第1帧的外观信息指导当前帧特征信息的提取;借助邻近数帧掩码图与当前帧特征图进行局部特征匹配,决策出与当前帧位置信息相关性较大的数帧作为邻近关键帧,用来指导当前帧位置信息的提取;借助改进的PAN特征聚合模块,将深层语义信息与浅层语义信息进行融合。结果 本文算法在DAVIS（densely annotated video segmentation）-2016数据集上的J和F得分为81.5%和80.9%,在DAVIS-2017数据集上为78.4%和77.9%,均优于对比方法。本文算法的运行速度为22帧/s,对比实验中排名第2,比PLM（pixel-level matching）算法低1.6%。在YouTube-VOS（video object segmentation）数据集上也取得了有竞争力的结果,J和F的平均值达到了71.2%,领先于对比方法。结论 多帧时空注意力引导的半监督视频分割算法在对目标物体进行分割的同时,能有效融合全局与局部信息,减少细节信息丢失,在保持较高效率的同时能有效提高半监督视频分割的准确率。     

空间约束层次加权Gamma混合模型的SAR图像分割

目的 合成孔径雷达（SAR）图像中像素强度统计分布呈现出复杂的特性,而传统混合模型难以建模非对称、重尾或多峰等特性的分布。为了准确建模SAR图像统计分布并得到高精度分割结果,本文提出一种利用空间约束层次加权Gamma混合模型（HWGaMM）的SAR图像分割算法。方法 采用Gamma分布的加权和定义混合组份;考虑到同质区域内像素强度的差异性和异质区域间像素强度的相似性,采用混合组份加权和定义HWGaMM结构。采用马尔可夫随机场（MRF）建模像素空间位置关系,利用中心像素及其邻域像素的后验概率定义混合权重以将像素邻域关系引入HWGaMM,构建空间约束HWGaMM,以降低SAR图像内固有斑点噪声的影响。提出算法结合M-H（Metropolis-Hastings）和期望最大化算法（EM）求解模型参数,以实现快速SAR图像分割。该求解方法避免了M-H算法效率低的缺陷,同时克服了EM算法难以求解Gamma分布中形状参数的问题。结果 采用3种传统混合模型分割算法作为对比算法进行分割实验。拟合直方图结果表明本文算法具有准确建模复杂统计分布的能力。在分割精度上,本文算法比基于高斯混合模型（GMM）、Gamma分布和Gamma混合模型（GaMM）分割算法分别提高33%,29%和9%。在分割时间上,本文算法虽然比GMM算法多64 s,但与基于Gamma分布和GaMM算法相比较分别快600 s和420 s。因此,本文算法比传统M-H算法的分割效率有很大的提高。结论 提出一种空间约束HWGaMM的SAR图像分割算法,实验结果表明提出的HWGaMM算法具有准确建模复杂统计分布的能力,且具有较高的精度和效率。     

基于图像分割的立体匹配算法

基于马尔可夫随机场（MRF）的立体匹配算法利用MRF模型来对匹配取值进行连续性约束。然而,MRF模型是产生式模型,图像自身特征难以得到准确描述。提出了一种基于图像分割的立体匹配算法SGC。SGC算法预先对图像进行分割,基于图像分割信息建立立体匹配的MRF模型,从而连续性（平滑）约束可以保留视差图中分割的边缘信息;并针对图像的深度连续性约束,定义了一个反映图像自身特征的新能量函数,应用于图割算法,提高了视差计算精度。实验结果表明,与以往算法相比,SGC算法更准确地反映了图像中深度信息,避免了平滑约束所引入的误差,有效提高了视差计算精度。     

结合相似性拟合与空间约束的图像分割

目的 图像中的目标一般含有很多子类,仅仅利用某个子类的特征无法完整地分割出目标区域。针对这一问题,提出一种结合相似性拟合与空间约束的图像交互式分割方法。方法 首先,通过手工标记的样本组成各个目标的字典,通过相似度量搜寻测试样本与各个目标的字典中最相似的原子建立拟合项;再结合图像的空间约束项,构建图像分割模型;最后利用连续最大流算法求解,快速实现图像分割的目的。结果 通过对比实验,本文方法的速度比基于稀疏表示的分类方法的速度提高约13倍,而与归一化切割(N-Cut),逻辑回归(logistic regression)等方法相比,本文方法能取得更稳定和准确的分割结果。此外,本文方法无需过完备字典,只需要训练样本能体现各个子类的信息即可得到稳定的图像分割结果。结论 本文交互式图像分割方法,通过结合相似性拟合以及空间约束建立分割模型,并由连续最大流算法求解,实现图像的快速准确的分割。实验结果表明,该方法能够胜任较准确地对自然图像进行分割以及目标提取等任务。     

实时视觉目标跟踪与视频对象分割多任务框架

目的 针对视觉目标跟踪（video object tracking,VOT）和视频对象分割（video object segmentation,VOS）问题,研究人员提出了多个多任务处理框架,但是该类框架的精确度和鲁棒性较差。针对此问题,本文提出一个融合多尺度上下文信息和视频帧间信息的实时视觉目标跟踪与视频对象分割多任务的端到端框架。方法 文中提出的架构使用了由空洞深度可分离卷积组成的更加多尺度的空洞空间金字塔池化模块,以及具备帧间信息的帧间掩模传播模块,使得网络对多尺度目标对象分割能力更强,同时具备更好的鲁棒性。结果 本文方法在视觉目标跟踪VOT-2016和VOT-2018数据集上的期望平均重叠率（expected average overlap,EAO）分别达到了0.462和0.408,分别比SiamMask高了0.029和0.028,达到了最先进的结果,并且表现出更好的鲁棒性。在视频对象分割DAVIS（densely annotated video segmentation）-2016和DAVIS-2017数据集上也取得了有竞争力的结果。其中,在多目标对象分割DAVIS-2017数据集上,本文方法比SiamMask有更好的性能表现,区域相似度的杰卡德系数的平均值J_M和轮廓精确度的F度量的平均值F_M分别达到了56.0和59.0,并且区域和轮廓的衰变值J_D和F_D都比SiamMask中的低,分别为17.9和19.8。同时运行速度为45帧/s,达到了实时的运行速度。结论 文中提出的融合多尺度上下文信息和视频帧间信息的实时视觉目标跟踪与视频对象分割多任务的端到端框架,充分捕捉了多尺度上下文信息并且利用了视频帧间的信息,使得网络对多尺度目标对象分割能力更强的同时具备更好的鲁棒性。     

鲁棒空间约束的模糊聚类图像分割

目的 为进一步提高分割精度,在模糊聚类的基础上引入统计信息,提出一种鲁棒型空间约束的模糊聚类分割算法。方法 基于局部空间信息的先验概率与后验概率,提出一种新型空间约束项,并通过卷积操作提高运行效率;进而引入负对数联合概率作为测度函数,进一步提高算法对于各像素点所属类别的甄别能力;同时将测度函数与空间约束项整合至目标函数中,通过迭代更新各参数达到最小化目标函数的目的。结果 对于合成图像的实验结果表明,本文算法对于噪声类型和噪声强度具有较强的鲁棒性;对于彩色图像的实验结果表明,在适当的特征描述符的辅助下,本文算法也能够获得令人满意的分割结果和较高的分割精度。结论 本文算法克服了现有算法的缺陷,进一步提升了图像的分割精度。其适用于分割带噪声图像,且在适当纹理特征的辅助下分割彩色图像,与同类算法的比较实验结果验证了本文算法的有效性。     

基于边缘约束局部区域MRF的图像分割方法

针对常规马尔科夫随机场（MRF）模型对复杂自然图像分割时,存在对噪声敏感且边缘模糊的问题,构建一种基于边缘约束局部区域MRF（ECLRMRF）的图像分割模型。利用欧氏距离度量局部区域内邻接像素的相似度,依据其相似度构建局部空间来约束高斯混合模型,有效描述丰富的局部区域统计特征,并建立MRF模型的局部区域一致性约束项。利用Canny边缘检测算子提取图像的边缘特征,并在分割过程中建立图像分割区域的边缘约束,通过在MRF模型框架下将局部区域统计特征和图像边缘特征相融合,解决局部区域MRF模型对图像分割边缘模糊的问题,再采用Gibbs采样算法实现对复杂自然图像的准确分割。实验结果表明,该模型能够更好地保留图像边缘信息,并且具有更好的分割效果。     

具有纹理感知能力的超像素分割方法

目的 超像素分割是计算机视觉领域常用的一项预处理技术,目标是将相邻像素聚集成为具有一定语义的子区域,能够大幅度降低后续处理的计算复杂度,但是对包含强梯度纹理的图像分割效果不佳,为此提出一种具有纹理感知能力的超像素分割方法。方法 提出一种能够区分强梯度噪声和纹理像素的颜色距离,其中利用带方向的1/4圆形窗口均值滤波后的颜色信息,提升包含强梯度噪声和纹理图像的超像素分割性能。利用区间梯度幅值与Sobel梯度幅值相乘得到混合梯度幅值,具有纹理抑制、结构保持以及边缘线条细的优点,能够提升超像素的贴合边缘性能,增强超像素形状规则程度。最后,利用混合梯度的幅值计算具有结构回避能力的综合聚类距离,进一步防止超像素跨越物体的边界,增强超像素的贴边性能。结果 在BSDS500（Berkeley segmentation dataset 500）图像数据集和强纹理马赛克图像等不同类型图像上的测试结果显示,与目前主流的超像素分割方法相比,本文算法在UE （undersegmentation error）、ASA （achievable segmentation accuracy）和CM （compactness measure）等性能指标上分别提高了1.5%、0.2%和4.3%。从视觉效果上看,能够在排除纹理干扰的情况下生成结构边缘贴合程度更好的形状规则超像素。结论 本文算法在包含强梯度纹理图像上的超像素分割性能优于对比方法,在目标识别、目标追踪和显著性检测等易受强梯度干扰的技术领域具有较大应用潜力。     

基于递归切片网络的三维点云语义分割与实例分割

目的 针对三维点云语义与实例分割特征点提取精度不高、实例分割精度极度依赖语义分割的性能、在密集场景或小单元分割目标中出现语义类别错分以及实例边缘模糊等问题,提出了基于递归切片网络的三维点云语义分割与实例分割网络。方法 网络对输入点云进行切片,并将无序点云映射到有序序列上;利用双向长短期记忆网络（bidirectional long short-term memory,BiLSTM）得到带有局部特征和全局特征的编码特征矩阵;将编码特征矩阵解码为两个并行分支,进行多尺度的特征融合;对语义与实例特征进行融合,得到并行的语义与实例分割网络。结果 在斯坦福大尺度3D室内场景数据集（Stanford large-scale 3D indoor spaces dataset,S3DIS）以及ShapeNet数据集上,与目前最新点云分割方法进行实验对比。实验结果表明,在S3DIS数据集上,本文算法的语义分割的平均交并比指标为73%,较动态核卷积方法（position adaptive convolution,PAConv）提高7.4%,并且在13个类别中的8个类别取得最好成绩;实例分割中平均实例覆盖率指标为67.7%。在ShapeNet数据集上,语义分割的平均交并比为89.2%,较PAConv算法提高4.6%,较快速、鲁棒的点云语义与实例分割方法（fast and robust joint semantic-instance segmentation,3DCFS）提高1.6%。结论 本文提出的语义与实例分割融合网络,综合了语义分割与实例分割的优点,有效提高语义分割与实例分割精度。     

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.