一种散乱点云空间直接剖分算法

散乱点云的三角剖分在曲面重建中发挥着重要作用。在对三角剖分基本方法深入分析的基础上对此类点云提出了一种高效的重构算法。本算法将基于动态球策略的搜索算法引入到曲面重建中,源于增量式计算的思想,结合约束准则和设计的顶点度量函数,从基础三角面片开始扩展到覆盖整个物体表面。分析及实验结果表明,该算法能有效地对点云数据进行三角网格化,同时剖分后的三角网格曲面最大限度地保持了原有曲面的特性,证明了提出的基于动态球的曲面重构算法应用于散乱点云曲面重构问题的可行性。     

多视角下的改进ICP算法

在逆向工程中,为处理庞大的三维点云数据,重建物体的表面,提出一种基于多视角的改进ICP算法。通过采集多视角下的点云数据,利用Delaunay三角剖分以及深度值信息对相邻两组点云的重合部分进行提取,根据三角面片重心与待测物体重心之间的距离将获得的点云数据进行分类配准,计算最优的旋转矩阵与平移向量,提高ICP算法的效率。实验结果表明,该算法能够提高配准精度,缩短配准时间,具有良好的稳定性。     

点云的形状与曲线重建算法

针对平面无序带噪点云的曲线重建问题,给出了点云形状的定义并提出了构造点云形状的算法.该算法基于Delaunay三角剖分,在构造好点云的Delaunay三角剖分后对三角剖分进行细化,使得在点云中的点周围形成空间上的局部均匀采样;基于集合论中的基本概念定义点云中内点、外点和边界点,并且明确地定义了点云的形状,根据Delaunay三角剖分细化时,选择不同的参数得到不同层次的点云的形状;选择合适的参数得到相应形状后,通过薄化过程得到具有流形结构的曲线.实验结果表明,采用文中算法得到的重建曲线很好地反映了点云的形状,验证了该算法的有效性.     

海量点云曲面增量拓扑重建EI北大核心CSCD

针对现有的曲面重建算法难以兼顾大规模采样数据的重建效率与重建曲面拓扑正确性的问题,提出一种基于局部Delaunay网格剖分的曲面增量重建算法.该算法采用波前扩展的策略,通过波前环的扩张、分裂、重叠面片的消除等步骤,将局部重建过程传播至每个样点的邻近区域,获得插值于采样点集的二维定向流形网格曲面,实现整个采样点集的增量拓扑重建;在曲面局部重建过程中,分别基于局部区域的Cocone算法与二维投影点集的Delaunay网格剖分方法重建曲面的尖锐区域与平坦区域,其中局部区域重建曲面网格的边界的正确性由区域之外的少量辅助样点保护.实验结果表明,文中算法具有较高的重建效率,适用于封闭和非封闭海量点云数据的重建;且在采样密度符合要求的情况下,重建的网格曲面与原表面拓扑同构.     

三维散乱点云快速曲面重建算法

提出了一种基于Delaunay三角剖分的三维散乱点云快速曲面重建算法。算法首先计算点云的Delaunay三角剖分, 从Delaunay四面体提取初始三角网格, 根据Voronoi体元的特征构造优先队列并生成种子三角网格, 然后通过区域生长的方式进行流形提取。实验结果表明, 该算法可以高效、稳定地重构具有复杂拓扑结构、非封闭曲面甚至是非均匀采样的点云数据。与传统的基于Delaunay的方法比较, 该算法仅需要进行一次Delaunay三角剖分, 无须极点的计算, 因此算法的重构速度快。     

机载激光雷达点云多层次建筑物的三维重建

针对城市区域中常见的多层次建筑物,提出一种基于机载LiDAR点云的三维重建方法。使用优化的随机抽样一致性算法对建筑物LiDAR点云进行面片分割,在面片分割的基础上使用delaunay三角剖分进行轮廓点的检测,对检测出的轮廓点使用新的关键点检测算法提取轮廓线关键点,最后连接关键点并进行规则化处理,完成多层次建筑物的三维重建。实验表明,该方法能有效重建多层次建筑物模型,改进的RANSAC算法能更高效地分割屋顶面片,新的轮廓线关键点提取算法能够较好地提取建筑物的关键点,并能抑制错误轮廓点的干扰,减少伪关键点的生成。     

海量点云曲面增量拓扑重建

针对现有的曲面重建算法难以兼顾大规模采样数据的重建效率与重建曲面拓扑正确性的问题,提出一种基于局部Delaunay网格剖分的曲面增量重建算法.该算法采用波前扩展的策略,通过波前环的扩张、分裂、重叠面片的消除等步骤,将局部重建过程传播至每个样点的邻近区域,获得插值于采样点集的二维定向流形网格曲面,实现整个采样点集的增量拓扑重建;在曲面局部重建过程中,分别基于局部区域的Cocone算法与二维投影点集的Delaunay网格剖分方法重建曲面的尖锐区域与平坦区域,其中局部区域重建曲面网格的边界的正确性由区域之外的少量辅助样点保护.实验结果表明,文中算法具有较高的重建效率,适用于封闭和非封闭海量点云数据的重建;且在采样密度符合要求的情况下,重建的网格曲面与原表面拓扑同构.     

一种基于点云数据的快速曲面重构方法

研究激光扫描中的点云数据重构技术,提出一种基于规则点云数据的快速曲面重构方法。分析相邻扫描线之间数据点的相对位置关系,在三角剖分的基础上,设计改进的扫描线剖分算法,根据激光逐行扫描的特点,对点云数据进行不规则三角网格划分,利用几何关系进行配对构网,并在所建三角模型的基础上实现三角网格的局部优化和纹理映射,得到重建模型。实验结果表明,与传统Delaunay空间三角剖分算法相比,该算法可明显提高三角构网速度和质量,消除空洞,改善重建效果。     

基于Delaunay规则的无组织采样点集表面重建方法

表面重建在3维地理信息系统、计算机辅助设计与图形学、计算机造型、逆向工程、虚拟仿真等应用领域有着广阔的应用前景。在前人研究的基础上,提出了一种基于Delaunay规则的3维表面重建方法,通过将局部采样顶点投影到局部切平面上,利用Delaunay规则对投影点进行约束三角剖分,并将剖分得到的顶点连接关系映射到3维空间中,即可得到采样点之间的相互连接关系,实现采样曲面S的表面重建。实验结果表明,算法在表面重建过程中可以有效检测不充分采样区域以及表面边界部分,适用于开、闭两种类型曲面的表面重建。此外,算法还具有实现简单、运行高效等优点。     

基于TIN的三维地质模型栅状图的司视化方法研究

三维地质模型的栅状图可视化方法研究是正确认识地质结构和构造复杂性的一种重要手段.本文提出一种栅状图生成方法首先针对不规则散点数据,应用基于格网划分的自适应分割-合并算法进行Delaunay三角剖分,快速高效地实现了三维地层三角面片的曲面重建在此基础上,对栅状图生成过程中需要进行的追踪三维体层剖切线、层间剖切线缝合等关键问题进行了探讨,并对其中的点定位算法进行了优化,有效提高了栅状图的生成效率.     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

Software-Konfigurationsmanagement in großen Softwareprojekten

Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel.     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and     

Editorial:Brain-machine interface(BMI) and cyborg intelligence

正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to control     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate     

SCIENCE CHINA Information Sciences SUBJECT INDEX TO VOLUME 57(2014)

正~~     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate