一种无标记点三维点云自动拼接技术

基于相位投影和双目的三维光学测量系统已经广泛应用于各领域.受投影光测量系统单次测量范围大小的限制,对大型物体的测量需要在表面粘贴圆形标记点进行多次拼接的缺点,探讨一种基于SIFT的无标记点自动拼接技术.该技术采用SIFT方法获取两次测量的特征点,其次结合RANSAC求出图像特征点的匹配关系,再根据立体匹配中图像特征点与三维点云之间的对应关系,将二维特征点的对应关系映射到三维点云的对应关系上,最后由SVD奇异值分解算法求得旋转和平移矩阵实现拼接.实验证明:该方法可以避免在被测量对象上粘贴标记点,能够快速准确地实现自动拼接.     

Medical augment reality using a markerless registration framework

This study proposes a cranial augmented-reality (AR) system which characterizes on performing image-to-patient registration using only natural facial features. Its hardware includes only three calibrated CCD cameras but any commercial spatial digitizing devices or artificial skin markers. Two of the cameras are mounted together to form a stereo-vision system, while the third camera moves freely and captures real-time images for AR-fusion display. The facial surface of a patient is first reconstructed by stereo vision. Meanwhile, another facial surface is reconstructed from preoperative computed tomography (CT) images of the patient. A iterative closest point (ICP)-based algorithm is then used to register the two facial data sets, which transfers the anatomical information from the CT images to the physical space. Since the natural of stereo-vision reconstruction usually accompanies with noisy data, the conventional ICP also suffers from its inherent local-minimum problem. Therefore, we propose an improved ICP which embeds a weighting and perturbing strategy to increase robustness and the ability of noise resistance. As a result, with a seamless integration among the preoperative CT images, the patient, the stereo-vision cameras, and the movable camera, an immersive medical AR environment based on a markerless image-to-patient registration is thus accomplished.     

Plane-based registration of construction laser scans with 3D/4D building models

With the development of building information modelling (BIM) and terrestrial laser scanning (TLS) in the architecture, engineering, construction and facility management (AEC/FM) industry, the registration of site laser scans and project 3D (BIM) models in a common coordinate system is becoming critical to effective project control. The co-registration of 3D datasets is normally performed in two steps: coarse registration followed by fine registration. Focusing on the coarse registration, model-scan registration has been well investigated in the past, but it is shown in this article that the context of the AEC/FM industry presents specific (1) constraints that make fully-automated registration very complex and often ill-posed, and (2) advantages that can be leveraged to develop simpler yet effective registration methods.This paper thus presents a novel semi-automated plane-based registration system for coarse registration of laser scanned 3D point clouds with project 3D models in the context of the AEC/FM industry. The system is based on the extraction of planes from the laser scanned point cloud and project 3D/4D model. Planes are automatically extracted from the 3D/4D model. For the point cloud data, two methods are investigated. The first one is fully automated, and the second is a semi-automated but effective one-click RANSAC-supported extraction method. In both cases, planes are then manually but intuitively matched by the user. Experiments, which compare the proposed system to software packages commonly used in the AEC/FM industry, demonstrate that at least as good registration quality can be achieved by the proposed system, in a simpler and faster way. It is concluded that, in the AEC/FM context, the proposed plane-based registration system is a compelling alternative to standard point-based registration techniques.     

Industrial geometry: recent advances and applications in CAD

Industrial Geometry aims at unifying existing and developing new methods and algorithms for a variety of application areas with a strong geometric component. These include CAD, CAM, Geometric Modelling, Robotics, Computer Vision and Image Processing, Computer Graphics and Scientific Visualization. In this paper, Industrial Geometry is illustrated via the fruitful interplay of the areas indicated above in the context of novel solutions of CAD related, geometric optimization problems involving distance functions: approximation with general B-spline curves and surfaces or with subdivision surfaces, approximation with special surfaces for applications in architecture or manufacturing, approximate conversion from implicit to parametric (NURBS) representation, and registration problems for industrial inspection and 3D model generation from measurement data. Moreover, we describe a ‘feature sensitive’ metric on surfaces, whose definition relies on the concept of an image manifold, introduced into Computer Vision and Image Processing by Kimmel, Malladi and Sochen. This metric is sensitive to features such as smoothed edges, which are characterized by a significant deviation of the two principal curvatures. We illustrate its applications at hand of feature sensitive curve design on surfaces and local neighborhood definition and region growing as an aid in the segmentation process for reverse engineering of geometric objects.     

DAO工作机制及注册方法研究

本文研究了DAO工作的机制，并给出向操作系统注册DAO的几种方法，可有效避免应用中出现“无法对DAO／JET DB引擎进行初试化”错误提示。     

谐波功率对感应式有功电度表计量的影响

谐波对感应式有功电度表计量的影响一直受到关注，但测量显示，现有的分析方法存在明显缺陷，不足以准确描述谐波引起的计量误差，谐波对感应式有功电度表计量的影响可分解为谐波功率和谐波电流影响的叠 加，该文主要分析谐波功率引起的计量误差。该文首先简要说明现有的分析方法所存在的问题，为了突破这些局限，该文将误差模型的推导建立在磁路分析的基础上，因为这更接近感应式有功电度表的工作原理。与现有的分析方法相比，该方法能够反映线路磁阻随频率的变化以及区分电压、电流元件中的工作磁通和非工作磁通，并且指出谐波功角偏移现象是因电压、电流元件中各部件磁阻的变化而产生，而不是只取决于电流元件中相位调整线圈参数的变化，实验分析显示该模型较好的吻合实际测量结果。     

支持个人移动的多代理系统网络协商思想

描述了支持个人移动,为用户提供智能接口以进行服务的多代理系统的结构和操作.本系统由下面的协议代理组成:个人通信代理（PCA）,给用户提供应用服务的智能接口;服务供应代理（SPA）,支持服务和用户间的通信;网络供应代理（NPA）,为SPA发出的请求提供网络连接.     

计算机集成外科手术系统中空间配准的应用研究

计算机集成外科手术系统是将机器人，计算机和图像处理技术应用于临床外科手术，是对传统手术的挑战。介绍了计算机集成外科手术系统中空间配准的基本原理，提出了基于轮廓特征的ICP配准算法。这种算法结合了ICP最优化解析方法和四元数法的优点，解决了图像轮廓点的空间配准问题。通过医学图像实例，证明了该方法的有效性。     

A new point matching algorithm for non-rigid registration

Feature-based methods for non-rigid registration frequently encounter the correspondence problem. Regardless of whether points, lines, curves or surface parameterizations are used, feature-based non-rigid matching requires us to automatically solve for correspondences between two sets of features. In addition, there could be many features in either set that have no counterparts in the other. This outlier rejection problem further complicates an already difficult correspondence problem. We formulate feature-based non-rigid registration as a non-rigid point matching problem. After a careful review of the problem and an in-depth examination of two types of methods previously designed for rigid robust point matching (RPM), we propose a new general framework for non-rigid point matching. We consider it a general framework because it does not depend on any particular form of spatial mapping. We have also developed an algorithm—the TPS–RPM algorithm—with the thin-plate spline (TPS) as the parameterization of the non-rigid spatial mapping and the softassign for the correspondence. The performance of the TPS–RPM algorithm is demonstrated and validated in a series of carefully designed synthetic experiments. In each of these experiments, an empirical comparison with the popular iterated closest point (ICP) algorithm is also provided. Finally, we apply the algorithm to the problem of non-rigid registration of cortical anatomical structures which is required in brain mapping. While these results are somewhat preliminary, they clearly demonstrate the applicability of our approach to real world tasks involving feature-based non-rigid registration.     

结构光测量中多视拼合技术与算法实现

基于定位点集（Locating Poinls Set）中任意两点间的相对距离不变这一基本特征,指出了定位和配准问题的实质是在两个不完全等价的特征点集中寻求最大同构子集的问题。本文创造性地引入了一种“不太可能发生的小概率事件”思维方式,结合结构光测量仪的自身特点,在人工交互的前提下,提出了一种基于结构光测量方法的自适应快速定位点识别及匹配算法,通过编程对算法进行了验证,并利用Surface软件对结果进行了可视化。