基于投影仪和摄像机的结构光视觉标定方法

为实现基于投影仪和摄像机的结构光视觉系统连续扫描,需要计算投影仪投影的任意光平面与摄像机图像平面的空间位置关系,进而需要求取摄像机光心与投影仪光心之间的相对位置关系。求取摄像机的内参数,在标定板上选取四个角点作为特征点并利用摄像机内参数求取该四个特征点的外参数,从而知道四个特征点在摄像机坐标系中的坐标。利用投影仪自身参数求解特征点在投影仪坐标系中的坐标,从而计算出摄像机光心与投影仪光心之间的相对位置关系,实现结构光视觉标定。利用标定后的视觉系统,对标定板上的角点距离进行测量,最大相对误差为0.277%,表明该标定算法可以应用于基于投影仪和摄像机的结构光视觉系统。     

双目视觉的立体标定方法

为实现双目视觉系统的立体标定,分析了摄像机成像模型,并充分考虑了透镜的径向畸变和切向畸变,提出了一种新的立体标定算法。该算法利用张正友的灵活标定算法,初步求取摄像机的内参数,结合Brown算法并提取图像中角点的子像素级坐标,精确求取摄像机内参数和畸变向量。为方便后续的图像校正,基于前面的单个摄像机标定,通过计算空间中的景物点在左右摄像机成像平面上的位置关系,计算出双目视觉系统中两个摄像机之间的旋转矩阵R和平移向量T,从而实现了立体标定。实验结果表明,该算法能取得较高的精度,可以应用于双目视觉系统。     

线结构光传感器参数现场标定方法

为了精确、快速、高效地标定线结构光传感器参数,提出了一种线结构光传感器参数现场标定方法。根据摄像机标定方法,并结合L-M非线性优化算法对摄像机内外参数及镜头畸变系数进行标定。拍摄不同姿态下的平面靶标图像,利用靶标图像计算摄像机外参计算靶标上的圆点在摄像机坐标系下的三维坐标,并构建靶标平面方程。将激光线投射到不同姿态的靶标平面上,通过靶标平面方程计算出激光线上点在摄像机坐标系下的3D坐标,由不同位置重构出激光点在摄像机坐标系下的3D坐标来完成光平面参数标定。通过对摄像机参数、畸变系数和光平面参数的标定,重构目标物体进行测试。测量结果表明:该算法能够快速、准确地获取小车车体的三维坐标,并构造出车体的三维模型。该方法适用于大视场的工业现场标定。     

基于单幅图像的摄像机畸变参数估计方法

摄像机畸变参数估计是摄像机标定的重要步骤.针对已有的摄像机畸变估计方法大多数为首先对无畸变下的摄像机参数进行标定,再进一步估计畸变参数,导致畸变参数估计过程复杂的问题.采用单应矩阵直接估计畸变参数,提出一种基于单幅图像的摄像机畸变参数估计算法.首先利用图像主点附近的图像特征点估计空间平面到图像平面的单应矩阵,然后利用该单应矩阵估计图像畸变误差和畸变参数,最后采用非线性优化算法对单应矩阵与畸变参数进行整体优化.模拟数据与实际图像的实验结果验证了本文算法的有效性;由于该算法仅需要1幅图像即可估计畸变参数,因此有效地提高了摄像机标定方法的灵活性.     

基于二维标定板的摄像机标定

当今摄像机的标定已然成为机器视觉领域研究的重点。在计算机获取图像并转换成数字信号实现三维欧式重建当中,摄像机的标定是非常关键的一步,采用2D共面激光打印标定板,基于Tsai模型两步标定法对摄像机进行标定。基于图像处理算法提取特征点坐标,然后对标定的初值进行多维无约束非线性优化,从而完成整个标定过程,并获得了对摄像机内外参数较为精确的求解。     

CCD摄像机标定的研究

在计算机视觉中,二维计算机坐标和三维物体空间坐标的关系可通过摄像机模型来建立.模型中的参数包括:摄像机几何、光学特性参数(内参数)及摄像机空间位置参数(外参数).摄像机的标定就是要确定这些参数.本文分析了三维空间点投影在像平面的像点产生畸变的原因:在大视场摄像机镜头各向同性,而且物像空间媒质均匀的情况下,像素单位元面积产生的变化引起像点畸变,并在实际图像坐标到计算机图像(帧存)坐标标定过程中推导出CCD传感器单元N方向的比例系数N<,x>的表达式,并进行了实验测量分析,取得的结果对提高标定精度具有意义.     

摄像机位姿的高精度快速求解

目的 针对对应点个数大于等于6的摄像机位姿估计问题,提出一种既适用于已标定也适用于未标定摄像机的时间复杂度为 的高精度快速算法。 方法 首先选取四个非共面虚拟控制点,并根据空间点和虚拟控制点的空间关系以及空间点的图像建立线性方程组,以此求解虚拟控制点的图像坐标及摄像机内参,再由POSIT算法根据虚拟控制点及其图像坐标求解旋转矩阵和平移向量。 结果 模拟数据实验和真实图像实验表明该算法时间复杂度和计算精度均优于现有的已标定摄像机位姿的高精度快速求解算法EPnP。 结论 该算法能够同时估计摄像机内外参数,而且比现有算法具有更好的速度和精度。     

多视角深度图配准算法下破损古建筑三维重建

为解决因古建筑结构复杂且序列杂乱导致的三维重建耗时过长、几何细节效果较差等问题,利用多视角深度图配准算法设计了新的破损古建筑三维重建方法.在标定摄像机坐标的基础上,确定摄像机与真实三维场景间的位置关系,然后采用棋盘角点信息标定法标定转轴的具体坐标,从而确定局部空间坐标.随后分别在相机坐标和世界坐标系统内提取建筑破损部分的所有点,融合两个点集即可实现三维重建.在仿真环境中,以图像工具库Open GL为处理平台,对破损大佛进行三维重建.实验结果表明:所提方法最终的呈现效果较好且抗干扰能力更强,能够满足实际操作要求.     

一种实用的平板高精度摄像机标定方法

在分析现有平板标定法所存在问题及完整摄像机模型的基础上,提出了一种实用的平板标定方法;首先,针对方格在进行亚像素角点提取时可能出现奇异点的问题对所有角点进行SVD分解;在未考虑畸变的情况下通过最小二乘法求取相机的初始内外参数;然后使用求取出来的初始内外参数及世界坐标求出理想图像坐标,根据畸变模型建立理想图像坐标和实际图像坐标之间的方程,解出畸变系数;最后采用LM算法作全局非线性优化,并根据反投影误差来控制角点校正及迭代运算,得到视觉系统更精确的内外参数;实验表明,该方法在对图像中心领域附近空间距离测量精度能到达0.0526mm,能满足高精度视觉测量及其它方面应用,迭代一次的情况下精度优于张正友方法。     

一种基于Kruppa方程的分步自标定方法

针对摄像机自标定中Kruppa方程求解的非线性优化问题和标定结果的欠鲁棒性,提出一种基于Kruppa方程的分步自标定方法。根据两图像匹配的特征点对采用8点算法求解相应的基本矩阵,其中待匹配图像选用摄像机对同一场景在不同焦距下拍摄的两帧图片,对图片的特征匹配点建立约束关系,采用最小二乘法求出摄像机的主点坐标,然后利用遗传算法优化Kruppa方程的比例因子,最后通过优化后的比例因子完成摄像机的标定。实验表明,该方法可提高标定精度,并通过对特征点坐标加入高斯噪声,验证了算法的鲁棒性。     

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