基于元学习和K均值聚类的高分遥感影像变化检测

为解决现有主流遥感影像变化检测方法在检测精度、自动化程度方面存在的局限性,提出一种基于元学习同/异质混合集成和K-means聚类的高分影像变化检测方法,可在较高检测精度下大幅缩减同/异质混合集成算法的运行时间。该方法首先以元学习为基础框架,选择同质集成的梯度提升树、随机森林和极端随机树作为元学习的初级学习器,快速重构原始样本的特征空间;然后利用K-means算法处理重构样本集,拟合多个逻辑回归次级学习器进行变化区域初检;最后采用超像元分割算法和空间邻域信息双重约束,滤除细小的“椒盐”碎斑。为验证该方法的有效性,选用两组不同地区的高空间分辨率遥感影像作为实验数据源。实验结果中,两组数据集上的Kappa系数分别为0.849 2和0.813 9,漏检率分别为0.132 1和0.215 2,误检率分别为0.148 2和0.101 7,处理耗时分别为65.217 s和700.441 s。结果表明,元学习算法结合K-means聚类的方法可有效提升变化检测精度,在算法效率方面也有良好的表现。     

一种基于改进土地覆盖更新方法的新增建设用地自动提取

快速准确掌握新增建设用地信息对城镇化监测研究具有重要意义。基于后验概率变化矢量检测的土地覆盖更新方法中,存在初始样本准确性低、后验概率变化矢量检测精度不理想的问题,结合多元变化检测方法,对基于后验概率变化矢量检测的更新方法进行改进,提出一种可应用于新增建设用地提取的自动化方法。利用两期影像多元变化检测结果提高初始训练样本的准确性,同时在迭代选择样本过程中加入该变化检测结果,改善变化检测更新和重分类过程的精度,更准确地提取新增建设用地。用两期嘉兴地区高分一号影像和前期影像土地利用/覆盖分类数据验证改进效果,并与改进前方法对比。结果表明：改进方法提取的2017年新增建设用地精度更高,提取更新后的2017年建设用地总体精度达到85%,Kappa系数0.7以上,变化检测精度比未改进前显著提高。同时该方法显著减少了迭代次数,提高了提取效率。     

一种基于改进土地覆盖更新方法的新增建设用地自动提取

快速准确掌握新增建设用地信息对城镇化监测研究具有重要意义。基于后验概率变化矢量检测的土地覆盖更新方法中，存在初始样本准确性低、后验概率变化矢量检测精度不理想的问题，结合多元变化检测方法，对基于后验概率变化矢量检测的更新方法进行改进，提出一种可应用于新增建设用地提取的自动化方法。利用两期影像多元变化检测结果提高初始训练样本的准确性，同时在迭代选择样本过程中加入该变化检测结果，改善变化检测更新和重分类过程的精度，更准确地提取新增建设用地。用两期嘉兴地区高分一号影像和前期影像土地利用/覆盖分类数据验证改进效果，并与改进前方法对比。结果表明：改进方法提取的2017年新增建设用地精度更高，提取更新后的2017年建设用地总体精度达到85%，Kappa系数0.7以上，变化检测精度比未改进前显著提高。同时该方法显著减少了迭代次数，提高了提取效率。     

一种基于改进土地覆盖更新方法的新增建设用地自动提取

快速准确掌握新增建设用地信息对城镇化监测研究具有重要意义。基于后验概率变化矢量检测的土地覆盖更新方法中,存在初始样本准确性低、后验概率变化矢量检测精度不理想的问题,结合多元变化检测方法,对基于后验概率变化矢量检测的更新方法进行改进,提出一种可应用于新增建设用地提取的自动化方法。利用两期影像多元变化检测结果提高初始训练样本的准确性,同时在迭代选择样本过程中加入该变化检测结果,改善变化检测更新和重分类过程的精度,更准确地提取新增建设用地。用两期嘉兴地区高分一号影像和前期影像土地利用/覆盖分类数据验证改进效果,并与改进前方法对比。结果表明:改进方法提取的2017年新增建设用地精度更高,提取更新后的2017年建设用地总体精度达到85%,Kappa系数0.7以上,变化检测精度比未改进前显著提高。同时该方法显著减少了迭代次数,提高了提取效率。     

基于Landsat TM数据的江苏海岸带土地利用/覆被变化检测方法比较研究

土地利用/覆被变化是全球环境变化研究的核心问题之一,选择适当的变化检测方法在江苏海岸带土地利用/覆被变化研究工作中具有重要意义。本研究选取江苏海岸带具有典型代表性的大丰市作为变化检测方法比较研究的试验区,采用1992年和2002年两期Landsat TM影像,分别运用主成分分析法、混合变化检测法和变化矢量分析法进行变化检测,提取土地利用/覆被变化信息,并对每种变化检测方法进行定量分析和综合比较。研究表明,主成分分析法对于试验区的土地利用/覆被变化研究具有检测速度快、检测精度高等优点,适合试验区以及整个江苏海岸带的土地利用/覆被变化的检测。最终,综合运用主成分分析法和分类后比较法获得了5期近30年江苏海岸带土地覆被分类图,证明了主成分分析法可有效应用于江苏海岸带的变化检测。     

一种改进型面向对象的遥感变化检测方法

针对人工变化发现效率低下和高分影像数据量大的现状,按照"先发现变化区域,再进行分类识别"的检测思路,提出了一种集成改进型变化矢量分析法和面向对象分类法的变化检测方法。该方法利用基于最大类间方差阈值搜索的改进型CVA法以自动快速提取出变化区域,再基于面向对象分类法对变化区域进行地物类型识别。为验证该方法的有效性,本文利用2009年和2013年两期IKONOS高分影像对重庆市沙坪坝区大学城建成区进行了变化检测实验,并采用变化检测一致性比率进行精度分析。实验结果表明,该方法对道路和建筑用地的变化检测精度可以达到85%以上,对耕地和水体的地类检测精度达到70%以上。可见,该方法在大区域的宏观土地利用遥感动态监测工作中具有一定的实用价值。     

城镇区域高分辨率遥感影像地表覆盖变化检测的误差分析

利用高空间分辨率遥感影像对土地利用/土地覆盖进行变化检测是国土监测的重要内容。但是,高分辨率影像存在一些中低分辨率影像所不具有的难点和不确定性,使得对城市区域进行变化检测获得的结果在阴影、图像配准、阈值选择、检测方法选择和图像后处理等方面的误差更为突出。基于ENVI和ERDAS软件中的工具,使用2009年和2012年两个时相的南京仙林航空彩色图像进行了变化检测,然后按照类内、类间地物类型进行了误差分析。结果表明:漏分误差的97.6%为类间误差,错分误差的87.1%为类内误差。按照误差的主要来源,漏分像素的72.6%来自于检测方法;错分像素的43.6%来自于检测方法、39.7%来自于辐射的不一致性。研究结果可为新变化检测算法的开发提供参考支持。     

一种面向对象遥感变化检测的影像分割策略

针对面向对象变化检测中进行影像分割时,对不同时相的两幅影像即使采用相同的分割参数,在未变化区域得到的分割结果也不完全一致,进而会造成一些伪变化区域的问题,提出了一种分割策略。为消除或减少这些伪变化区域的影响,该策略在利用第一期影像分割结果的基础上对另一期影像进行两次分割,即首先对第一期影像采用合适的尺度进行分割,生成对象单元,而对第二期影像采用两次分割的策略:第一次利用第一期影像的分割结果作为专题数据对其进行分割,在第一次分割的基础上采用更小尺度对其再次分割。论文通过实验对所提出分割策略的有效性进行了验证。结果表明:使用分割策略可在一定程度上避免由于未变化地物分割不一致而造成的伪变化区域,从而提高了变化检测结果的精度。     

基于小波系数差值法的变化信息自动发现

本文将二维小波变换应用于土地利用遥感动态监测，以自动探测土地利用变化信息。在对两时相多光谱影像主成分变换的基础上，选择前面三个主分量进行小波变换，对两时相对应主分量的小波系数求差，土地利用未发生变化区域的差值接近0，而发生变化区域的差值绝对值较大，能量高，因此，经小波逆变换得到的影像能够高亮度地显示出土地利用发生变化的区域。利用遥感数据进行仿真和野外验证发现。该方法得到的监测结果精度能满足实际应用的需要。     

融合光谱与地形因子的土地利用/覆被变化检测

针对仅利用遥感影像单一光谱指数提取土地利用/覆盖变化信息精度较低的问题,提出融合光谱与地形因子的土地利用/覆盖综合变化检测方法,用于提高总体变化检测精度。首先利用互补的4个光谱检测指标获得尽可能消除季相差异误差的初始变化检测结果,然后根据坡度、坡向剔除因山体阴影造成的虚检部分。以江西省西南地区Landsat TM影像为例,对比了融合光谱和地形因子的综合变化检测方法与仅利用光谱信息的分类后变化检测方法的结果,表明前者的变化检测精度比后者提高了13.67%,且虚检率降低了15.56%,这说明融合光谱和地形因子的综合变化检测方法能够显著提高遥感变化检测精度。     

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.