改进TrICP算法的多源点云配准研究

针对建筑物多源点云数据配准时出现配准精度低和效率不高的问题,提出一种基于主成分分析(PCA)的改进修剪迭代最近点(TrICP)多源数据配准方法。首先采用PCA算法对点云计算主轴方向,并基于方向反向问题创建校正矩阵进行校正,从而得到两组点云的初始良好位姿转换,完成点云的粗配准步骤;然后针对修剪迭代最近点中搜索点对和迭代次数问题,采用赋权的改进修剪迭代最近点算法完成两种点云数据的精配准。实验数据结果表明,改进的配准算法可以有效地减少多源点云数据迭代次数,提高配准精度并且保证了点云的完整性,相较于其他三种对比算法,精度分别提高56.75%、39.60%、28.08%,有效提升了配准的效率。     

室内移动机器人目标定位性准确匹配研究

在室内移动机器人目标定位系统中的扫描匹配技术中,传统的迭代最近点算法存在待配准点云初始位置要求苛刻、难以找到正确对应点对的问题,因此提出一种基于Kinect传感器获取三维环境点云,根据旋转投影统计特征描述子的相似性来查找对应点对并进行扫描匹配的移动机器人目标定位方法。首先通过Kinect传感器获取物体点云图,根据特征提取算法提取点云特征;然后获取两个待匹配点云的旋转投影统计特征描述子,通过比较两个描述子之间特征的相似程度,估算它们之间的对应关系,采用距离差分矩阵算法剔除误匹配点,计算初始匹配参数;最后利用最小二乘法迭代进行ICP配准,获得点云间的最终变换矩阵,实现目标定位。实验结果表明,改进后的算法有效地提高了点云匹配效率和配准精度,得到了较精确的目标定位信息。     

基于深度相机的机器人室内定位技术研究

机器人在室内运动时,需要创建环境地图并估计位姿,以实现自主定位和导航。针对机器人的同时定位与地图创建(SLAM)问题,采用动态贝叶斯网络描述SLAM状态转移过程。通过不断迭代更新机器人的位置估计和修正估计值,完成机器人的室内定位。基于深度相机采集的RGB图像信息,进行相邻帧图像的特征提取与匹配,估算机器人当前位姿。然后使用迭代最近点算法优化初始位姿。以初始位姿为节点,相邻帧的约束关系为边创建节点图。进一步采用Hogman算法对整个节点图进行动态优化,得到全局一致的室内地图。最后根据优化后的节点图,多帧数据叠加就可得到三维地图。实验采用华硕Xtion Pro Live深度相机,实验室地点为目标,成功创建了环境的三维地图,验证了方法的有效性和可行性。     

采用主成分分析的迭代最近点算法优化与验证

通过分析算法配准过程提出一种基于主成分分析（PCA）的点云配准策略,对迭代最近点（ICP）算法迭代过程加入PCA配准设计,以解决ICP算法易陷入局部最小值、配准耗时高的问题。首先,利用重心法在首次迭代开始前使参考点云与待配准点云重心重合以达到初始位姿确定;然后,在ICP算法每次进行迭代时,先对待配准点云与参考点云进行PCA,选取其中前三主成分特征向量,通过姿态变换进行对应匹配,使两点云完成初始配准后再利用欧氏距离寻找最近点,完成后续配准过程。选取了经典ICP算法及3种初始位姿确定方法、文献主流算法与提出的迭代PCA算法及3种初始位姿确定方法进行对比分析,结果表明,在前述两种方法都无法配准的情况下,提出算法不仅成功避免算法陷入局部最小,而且获得了较优的速度与精度,迭代次数为10次,耗时19.427939 s,配准误差为2.1932,综合提高了配准性能。     

基于视点特征直方图的激光点云模型的位姿估计

提出一种基于视点特征直方图的点云模型位姿估计 算法。首先在目标物体周围采 集三维点云,拼接后获得物体的完整点云模型;然后对点云模型计算其视点特征直方图, 构建特征数据 库;对待估计点云同样计算其特征直方图,使用KNN算法在数据库中搜索与之最接近的位 姿作为初始位 姿估计值;最后使用迭代最近点(ICP)算法将待估计点云精确配准到模型点云,从而获得坐 标系之间的相 对位姿。实验表明,这种方法对于物体位姿识别有很强的稳健性,能很好实现目标物体的 三维位姿计算。     

基于超体素与几何特征融合的点云配准优化

针对点云配准过程中点云数据冗余、易出现误匹配点对和配准精度低的问题,提出了一种融合超体素及几何特征的点云配准方法。首先使用超体素与法向量信息相结合的方法提取特征点;其次,在粗配准中,通过使用快速特征点直方图(Fast Point Feature Histograms,FPFH)进行特征描述,采用双向最近邻比获取初始特征点对应关系,基于法向量夹角策略和随机采样一致性(Random Sample Consensus,RANSAC)算法进行对应关系的优化,获取良好的初始位姿;最后,在精配准中,基于初始位姿与改进的迭代最近点算法(Iterative Closest Point,ICP)算法完成点云配准。通过在斯坦福数据集中进行配准实验,验证了所提算法具有更好的鲁棒性,能高效且精准的完成点云配准。     

一种基于特征提取的点云自动配准算法

针对在不同视角下所获得的三维点云数据,提出了一种基于特征提取的点云自动配准算法。算法根据点云在不同半径内的法向量变化度来提取特征点,综合利用点云局部点的三种几何特征搜索匹配点对。通过利用距离约束条件来获取准确匹配点对并计算初始配准参数。精确配准阶段采用改进的迭代最近点(ICP)算法完成二次拼接。实验结果表明,与传统ICP算法相比,该算法在运行时间与精确度上都有着明显的提升。     

面向室内动态场景的VSLAM

传统VSLAM算法基于静态场景实现,其在室内动态场景下定位精度退化,三维稀疏点云地图也会出现动态特征点误匹配等问题.文中在ORB-SLAM2框架上进行改进,结合Mask R-CNN进行图像的语义分割,剔除位于动态物体上的动态特征点,优化了相机位姿,得到了静态的三维稀疏点云地图.在公开的TUM数据集上的实验结果表明,结合...     

基于快速点特征直方图的三维点云配准算法

三维点云配准算法是三维场景模型重建的重要研究部分。针对传统迭代最近点算法(ICP)对点云进行配准时容易陷入局部最优的问题,本文研究了基于局部特征点改进的ICP算法。文章分析了点特征直方图(PFH)和快速点特征直方图(FPFH)两种局部特征点,得出了FPFH具有比PFH更低的时间复杂度的结论,因此通过FPFH特征描述子对两片初始点云进行粗配准,使其具有较好的初始位姿,最后用经典的ICP算法进行精配准。实验结果表明,基于FPFH特征点改进后的ICP算法能提供较好的点云初始位姿,一定程度上避免了配准时陷入局部最优的问题,比传统ICP算法具有更好的配准效果。     

基于ISS特征点结合改进ICP的点云配准算法北大核心CSCD

针对点云配准时间长、收敛缓慢、对应点匹配易错等缺点,提出一种基于内部形态描述子(ISS)特征点结合改进迭代最近点(ICP)的点云配准算法。首先采用ISS算法进行点云特征提取,并以快速点特征直方图进行特征描述,然后通过采样一致性算法完成点云的初始配准,使两片不同角度点云获得一个相对较好的初始位姿,最后通过k维树近邻搜索法加速对应点对的查找,以提高点云ICP精细配准效率。实验结果表明,与传统配准算法相比,该算法配准精度高,而且执行速度快。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.     

Call for Papers

正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks