基于多幅实拍照片为真实景物模型添加纹理

利用实拍照片为基于真实景物创建的几何模型添加纹理的方法正在受到广泛的关注,实拍照片与几何模型的配准是这项技术的关键.以往方法采用3D-2D特征点匹配或侧影轮廓线匹配的方法进行配准,因此对空间物体的表面特征或轮廓线形状有特殊的要求.提出了一种新的配准方法来解决这一问题,由于采用了基于图像重建的采样点模型与已知几何模型在空间中匹配的方法实现配准,因而充分利用了物体几何形状本身的拓扑和曲率等信息,并可以一次性地实现所有图像与空间物体的配准.实验结果表明,该方法可以解决一部分用以往的方法尚无法处理的实际问题,且在重建空间采样点分布较为合理的情形下,纹理映射效果非常理想.     

真实感三维模型的纹理融合

提出一种消除物体表面纹理接缝,重建高精度真实感三维模型的纹理融合方法.首先将不同视场的深度图像匹配到同一坐标系下,经过深度图像融合获得物体完整的几何模型;然后确定深度图像和纹理图像的映射关系,并定义复合权重进行纹理融合来获取整个纹理映射图,并进行模型的纹理映射.该方法可消除物体表面重叠区域由于光照变化、几何模型的非完全漫反射以及拍摄视场的改变等外界因素引起的色彩差异,重构真实感三维模型;且对物体的几何形状、拍摄视场没有限制,能够自由拍摄,并实现高精度三维纹理模型.实验结果表明,文中方法是有效和鲁棒的.     

一种基于双幅图像的物体3维重建

随着虚拟现实技术的发展,对物体进行快速有效建模逐渐成为了研究热点。基于图像建模技术是一种有效的建模方法,其最大的优点是可以利用图像中的信息直接建立物体的几何模型,并且可以迅速构建出具有“照片级”真实感的3维模型。常规的方法是先求解摄像机内外参数,再求解空间中各点在世界坐标系下的位置。提出了一种基于两幅图像利用灭点性质进行建模的新方法。该方法首先利用灭点属性推导出了相机中心在世界坐标系下的坐标位置的解析表达式,再利用两幅图像之间的空间几何约束关系,从空间约束关系中反算出物体各点的空间位置从而重建出物体几何模型,最后进行纹理映射。在物体重建的过程中只利用到了相机内参数,而跳过了对相机外参数的标定,实验结果表明,该方法简单可靠,可用于实现对拥有规则表面的物体3维重建。     

基于立体视觉的鞋楦数字化研究

针对鞋楦图像在三维重建中的匹配问题,提出一种改进的鞋楦数字化方法。对鞋楦表面做纹理网格化处理,利用Harris与Laplace算子相结合的方法提取特征点,采用改进的去除误匹配方法进行精匹配,通过双目视觉三角测量法求出匹配点的三维坐标。使用迭代近邻点算法实现不同方向点集的坐标融合和三维拼接,对全部三维点云数据进行三角网格化和曲面拟合,完成鞋楦三维重建。实验结果表明,该方法能便捷、高效地实现鞋楦数字化重建,可满足个性化制鞋需求。     

点云数据集的隐式曲面重构研究进展

点云数据的曲面重建就是对扫描设备获得的物体散乱数据点重建三维物体表面,它被广泛应用于计算机动画、目标识别、数据可视化以及地理信息系统。点云的隐式曲面重建由于能够去除点云噪声,修补孔洞和裂缝,不需要拼接和平滑等后续处理,成为点云数据集曲面重构的重要方法。文中综述了目前一些主要的隐式曲面重构方法,就隐式模型以及相应的曲面重构算法的优缺点进行了分析比较,并对隐式曲面重构存在的问题和未来发展方向作了相应的分析和讨论。     

一种为三维物体表面添加纹理的精确方法*

针对真实物体进行三维数字化重建的工程中,物体的空间位置及色彩等特征的数据采集始终是一项困难的,同时却又是十分重要的工作,设计的三维光学数字成像系统可以同时采集物体在同一个方向的深度图像和与它精确对应的纹理图像,在深度图像合成的同时进行纹理图像的融合.在进行多视角的纹理图像融合时,对权函数的设定提出了新的准则,使融合后的纹理图像更加逼真,可以产生高真实感的物体三维数字化模型.     

基于三维模型几何信息的纹理图像压缩

为进一步压缩三维模型数据,提高网络传输的速度,同时不降低模型渲染的视觉表现效果.提出了一种基于三维模型几何信息的纹理图像压缩算法.首先对模型三维网格做重网格化,使网格具备半正则的规则拓扑结构;然后利用半正则网格表面的几何信息对模型的三维特征点进行提取,对三维特征点在纹理空间的映射点应用k-means聚类算法获取感兴趣区域;最后结合基于感兴趣区域的嵌入式零树小波压缩算法,实现对模型纹理图像数据的编码和解码操作.实验结果表明,该算法提取的纹理图像感兴趣的细节区域更精确、压缩比高,经过解码和重建后的纹理图像在对三维模型表面贴图映射后具有更好的视觉效果.     

逆向工程中基于三目视觉自动提取并构造复杂曲面边界技术

在逆向工程中复杂曲面零件表面的几何模型的构造是研究重点之一，根据零件表面 的数字化数据提取零件表面的边界是构造零件几何模型的关键步骤．本文提出基于三目视觉 方法来提取和构造复杂曲面边界的技术．从一幅图像中提取反映物体边界的特征点，再利用 图像匹配方法得到这些特征点的空间坐标，最后以这些特征点构造出物体边界B样条曲线．     

基于三维激光扫描的物体重构建模

物体拍摄环境具有测量数据量大、物体外轮廓信息复杂等特点,采用当前方法能够获得物体精确的三维点云数据,但缺乏颜色和纹理信息,导致物体重构精度不高,真实感较差;为此,提出一种基于三维激光扫描的物体重构建模方法;该方法通过三维激光扫描技术获取物体点云数据,采用显式的欧拉积分方法对物体整个三维曲面进行平滑,依据三角生长法进行物体三维空间三角划分,将物体网格顶点向球面进行映射,由此构造物体三角网格模型,通过迭代最近点算法对物体非同步点云数据初步匹配结果进行精确配准,利用最近点搜索算法将经多视图立体视觉算法优化后的物体颜色信息和三维点云数据坐标相融合;实验结果表明,所提方法可以快速精确地建立物体三维重构模型,验证了所提方法的可行性。     

一种基于深度和颜色的3D表面重建方法

为了快速、有效地对三维物体的表面进行重建，提出了一种基于深度和颜色的3D表面重建方法。该方法利用同一物体在空间稀疏分布的不同视点下的多幅深度图像，根据3D物体表面同一点在不同深度图像上颜色和纹理的一致性，通过逆投影变换，可将图像中像素点映射到三维空间中的正确位置。然后在以物体为中心的单个坐标系下，进行数据融合，可得到三维物体表面各点的三维数据。实验结果表明该方法具有复杂度恒定、获取图像真实感强等优点，适用于形状、结构草杂的物体重建。     

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)

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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