Control and data acquisition system for collinear laser spectroscopy experiments

A control and data acquisition system was implemented for the recently developed collinear laser spectroscopy setup.This system is dedicated to data recording,storage,processing,monitoring of the beam intensity and energy,and visualization of various spectra.In comparison to the conventional resonance nuclear reaction system,the key technique is the precise synchronization of the detected counts with the actual scanning voltage(or probing laser frequency).The functions of the system were tested by measuring the hyperfine structure spectra of stable calcium(e.g.,^(40)Ca^(+))and radioactive potassium(e.g.,^(38)K)in the bunched and continuous modes,respectively.This system will be routinely applied and further improved in subsequent laser spectroscopy experiments on unstable isotopes at the Beijing Radioactive Ion-beam Facility(BRIF).

Generation of 3D Virtual Geographic Environment Based on Laser Scanning Technique

This paper demonstrates an experiment on the generation of 3D virtual geographic environment on the basis of experimental flight laser scanning data by a set of algorithms and methods that were developed to automatically interpret range images for extracting geo-spatial features and then to reconstruct geo-objects. The algorithms and methods for the interpretation and modeling of laser scanner data include triangulated-irregular-network (TIN)-based range image interpolation; mathematical-morphology (MM)-based range image filtering, feature extraction and range image segmentation, feature generalization and optimization, 3D objects reconstruction and modeling; computer-graphics (CG)-based visualization and animation of geographic virtual reality environment.

Optimized air-ground data fusion method for mine slope modeling

Refined 3D modeling of mine slopes is pivotal for precise prediction of geological hazards.Aiming at the inadequacy of existing single modeling methods in comprehensively representing the overall and localized characteristics of mining slopes,this study introduces a new method that fuses model data from Unmanned aerial vehicles(UAV)tilt photogrammetry and 3D laser scanning through a data alignment algorithm based on control points.First,the mini batch K-Medoids algorithm is utilized to cluster the point cloud data from ground 3D laser scanning.Then,the elbow rule is applied to determine the optimal cluster number(K0),and the feature points are extracted.Next,the nearest neighbor point algorithm is employed to match the feature points obtained from UAV tilt photogrammetry,and the internal point coordinates are adjusted through the distanceweighted average to construct a 3D model.Finally,by integrating an engineering case study,the K0 value is determined to be 8,with a matching accuracy between the two model datasets ranging from 0.0669 to 1.0373 mm.Therefore,compared with the modeling method utilizing K-medoids clustering algorithm,the new modeling method significantly enhances the computational efficiency,the accuracy of selecting the optimal number of feature points in 3D laser scanning,and the precision of the 3D model derived from UAV tilt photogrammetry.This method provides a research foundation for constructing mine slope model.

Indoor Space Modeling and Parametric Component Construction Based on 3D Laser Point Cloud Data

In order to enhance modeling efficiency and accuracy,we utilized 3D laser point cloud data for indoor space modeling.Point cloud data was obtained with a 3D laser scanner and optimized with Autodesk Recap and Revit software to extract geometric information about the indoor environment.Furthermore,we proposed a method for constructing indoor elements based on parametric components.The research outcomes of this paper will offer new methods and tools for indoor space modeling and design.The approach of indoor space modeling based on 3D laser point cloud data and parametric component construction can enhance modeling efficiency and accuracy,providing architects,interior designers,and decorators with a better working platform and design reference.

Integration system research and development for three-dimensional laser scanning information visualization in goaf

An integration processing system of three-dimensional laser scanning information visualization in goaf was developed. It is provided with multiple functions, such as laser scanning information management for goaf, cloud data de-noising optimization, construction, display and operation of three-dimensional model, model editing, profile generation, calculation of goaf volume and roof area, Boolean calculation among models and interaction with the third party soft ware. Concerning this system with a concise interface, plentiful data input/output interfaces, it is featured with high integration, simple and convenient operations of applications. According to practice, in addition to being well-adapted, this system is favorably reliable and stable.

A Novel Airborne 3D Laser Point Cloud Hole Repair Algorithm Considering Topographic Features

Hole repair processing is an important part of point cloud data processing in airborne 3-dimensional(3D)laser scanning technology.Due to the fragmentation and irregularity of the surface morphology,when applying the 3D laser scanning technology to mountain mapping,the conventional mathematical cloud-based point cloud hole repair method is not ideal in practical applications.In order to solve this problem,we propose to repair the valley and ridge line first,and then repair the point cloud hole.The main technical steps of the method include the following points:First,the valley and ridge feature lines are extracted by the GIS slope analysis method;Then,the valley and ridge line missing from the hole are repaired by the mathematical interpolation method,and the repaired results are edited and inserted to the original point cloud;Finally,the traditional repair method is used to repair the point cloud hole whose valley line and ridge line have been repaired.Three experiments were designed and implemented in the east bank of the Xiaobaini River to test the performance of the proposed method.The results showed that compared with the direct point cloud hole repair method in Geomagic Studio software,the average repair accuracy of the proposed method,in the 16 m buffer zone of valley line and ridge line,is increased from 56.31 cm to 31.49 cm.The repair performance is significantly improved.

Methodology for Extraction of Tunnel Cross-Sections Using Dense Point Cloud Data

Tunnel deformation monitoring is a crucial task to evaluate tunnel stability during the metro operation period.Terrestrial Laser Scanning(TLS)can collect high density and high accuracy point cloud data in a few minutes as an innovation technique,which provides promising applications in tunnel deformation monitoring.Here,an efficient method for extracting tunnel cross-sections and convergence analysis using dense TLS point cloud data is proposed.First,the tunnel orientation is determined using principal component analysis(PCA)in the Euclidean plane.Two control points are introduced to detect and remove the unsuitable points by using point cloud division and then the ground points are removed by defining an elevation value width of 0.5 m.Next,a z-score method is introduced to detect and remove the outlies.Because the tunnel cross-section’s standard shape is round,the circle fitting is implemented using the least-squares method.Afterward,the convergence analysis is made at the angles of 0°,30°and 150°.The proposed approach’s feasibility is tested on a TLS point cloud of a Nanjing subway tunnel acquired using a FARO X330 laser scanner.The results indicate that the proposed methodology achieves an overall accuracy of 1.34 mm,which is also in agreement with the measurements acquired by a total station instrument.The proposed methodology provides new insights and references for the applications of TLS in tunnel deformation monitoring,which can also be extended to other engineering applications.

A landslide monitoring method using data from unmanned aerial vehicle and terrestrial laser scanning with insufficient and inaccurate ground control points

Non-contact remote sensing techniques,such as terrestrial laser scanning(TLS)and unmanned aerial vehicle(UAV)photogrammetry,have been globally applied for landslide monitoring in high and steep mountainous areas.These techniques acquire terrain data and enable ground deformation monitoring.However,practical application of these technologies still faces many difficulties due to complex terrain,limited access and dense vegetation.For instance,monitoring high and steep slopes can obstruct the TLS sightline,and the accuracy of the UAV model may be compromised by absence of ground control points(GCPs).This paper proposes a TLS-and UAV-based method for monitoring landslide deformation in high mountain valleys using traditional real-time kinematics(RTK)-based control points(RCPs),low-precision TLS-based control points(TCPs)and assumed control points(ACPs)to achieve high-precision surface deformation analysis under obstructed vision and impassable conditions.The effects of GCP accuracy,GCP quantity and automatic tie point(ATP)quantity on the accuracy of UAV modeling and surface deformation analysis were comprehensively analyzed.The results show that,the proposed method allows for the monitoring accuracy of landslides to exceed the accuracy of the GCPs themselves by adding additional low-accuracy GCPs.The proposed method was implemented for monitoring the Xinhua landslide in Baoxing County,China,and was validated against data from multiple sources.

基于3D激光扫描技术的粗集料三维形态特征分析

为了能够建立精确的沥青混合料细观力学模型、优化混合料性能,需要先构建具有真实形态学特征的集料模型并计算分析集料形态参数,利用3D激光扫描技术采集了辉绿岩、石灰岩、玄武岩与卵石4种集料共500颗样本的三维点云数据,通过球谐函数简化集料模型,建立了三维集料样本库。归纳总结了现有集料的形态指标,通过皮尔逊相关性分析,选取F_(I)、A_(I)定量表征粗集料三维形态特征,对不同种类以及粒径集料的F_(I)、A_(I)进行统计分析。研究结果显示:当球谐序列阶数为10,三角形映射网格数为643时,简化后集料模型基本形状、体积与表面积均与真实集料非常接近;集料的F_(I)、A_(I)服从正态分布与对数正态分布,且随集料类型和粒径的变化而变化。

特征自适应的复杂曲面扫描路径生成方法

为了解决现有自动化扫描方法在面对复杂曲面时扫描完整性不足、普适性不佳等问题,提出了一种特征自适应的自动化扫描路径规划方法。首先,构建了激光扫描仪的扫描约束条件,分析其对扫描精度的影响,为特征自适应的复杂扫描路径规划提供理论支撑。其次,针对扫描仪姿态规划问题,提出了一种新的测量倾角约束聚类算法,对离散复杂曲面后获得的采样点进行聚类处理,实现扫描仪姿态的规划,并在此基础上获得扫描路径点。再次,针对扫描路径规划问题,引入法向矢量夹角矩阵作为惩罚矩阵,优化改进最近邻算法,实现符合需求的扫描路径规划。最后,为验证该方法可行有效,以汽车车门作为扫描对象,搭建了一个组合式自动化柔性测量系统,与传统行切扫描方法、手动扫描方法进行对比试验。试验结果表明,该方法相较于行切扫描方法在扫描仪姿态变换次数上减少了54%,测量精度提高了64.5%,降低了人工干预因素的影响,扫描完整性与手动扫描方法接近,可以实现针对复杂曲面的自动化扫描测量。

ACQUIREMENT AND COMPUTER PROCESSING OF 3-D SURFACE SHAPE DATA

The laser scanning and CCD image-transmitting measurement method and principle on acquiring 3-D curved surface shape data are discussed. Computer processing technique of 3-D curved surface shape(be called“ 3 - D surface shape”for short) data is analysed. This technique in- cludes these concrete methods and principles such as data smoothing, fitting, reconstructing ,elimi- nating and so on. The example and result about computer processing of 3- D surface shape data are given .

三维激光扫描技术在建筑变形监测中的应用

三维激光扫描技术是通过利用高速激光扫描测量的方法,复建出1∶1三维点云模型的一种全新技术手段。在广西壮族自治区某商务主楼钢结构变形监测中,通过运用三维激光扫描技术获取建筑信息,并结合点云处理软件、CAD插件等软件,进行数据全面分析,完成对该超高层建筑物钢框架主体水平方向的变形监测。由此总结出三维激光扫描技术在建筑变形监测中的应用流程,为未来建筑的变形监测提供借鉴参考。

贫数据小型水利工程结构安全分析

我国小型水库数量多,溃坝多发,运行风险大。为了保障水库的安全稳定运行,有必要对小型水库的结构安全分析和评估进行深入研究。由于小型水库大多建于20世纪50—70年代,各类工程资料匮乏,难以进行结构安全分析工作。以北京地区一小型拱坝为例,采用地面三维激光扫描测绘技术对大坝进行扫描,将所得点云数据集进行编辑、配准、拼接处理,生成三维模型导入有限元分析计算软件进行结构稳定分析。坝体建模网格及单元划分质量高,满足计算精度的要求,分析计算成果与客观规律一致,这为资料匮乏的小型水利工程结构安全分析提供了一种新思路。

基于多视数据重构损失标定的叶片型面光学检测

航发叶片型面检测是保证叶片加工质量、工作性能和使用寿命的关键环节。对此,该文开发一套基于线激光器的叶片型面检测平台;在完成线激光器与叶片相对位姿校准及Z向测量基准建立基础上,实现叶片型面特定截面处型线数据的多视采集;提出一种基于多视数据重构损失标定回转中心的型线重构方法。以两种典型燃气轮机导向叶片为检测对象,所提出方法获取的检测数据与三坐标测量机检测数据的对比结果表明,轮廓度检测平均绝对偏差在0.022 mm以内,最大标准偏差为0.0186 mm,最大RMS估计为0.0251 mm;特征参数检测最大偏差为0.0401mm。实验结果验证了所提出方法面向叶片型面检测的可行性。

基于激光扫描的电子档案异构时态数据检测方法

研究一种基于激光扫描的电子档案异构时态数据检测方法,该方法利用激光扫描获取数据并生成电子档案。针对电子档案中的数据实施缺失数据填补和离群数据处理。提取电子档案数据的递归率、仙农熵以及歪度三个特征。结合随机森林算法,输入递归率、仙农熵以及歪度三个特征,得出电子档案异构时态数据类型。结果表明:1处和3处边坡工程的位移处于轻微状态;2处边坡工程的位移处于严重状态;4处边坡工程的位移处于安全状态;5处边坡工程的位移处于较严重状态。所研究方法的Kappa系数达到相对最大值,说明所研究方法的检测能力更高。

地面激光扫描点云与无人机影像点云融合应用

通过建立高精度的桥梁三维点云模型,检查桥梁病害情况并拟合绘制出桥梁线形。首先以无人机近景摄影、环绕飞行、井字飞行获取某双线特大桥梁主体与细部纹理数据,然后将不同航线采集的数据在Context Capture软件里面进行三维重建,将桥梁主体与细部影像融合生成完整桥梁点云1。运用Trimble SX12仪器完成对桥梁一体化扫描,获得完整桥梁点云2。提出基于双向KD-tree优化的ICP(Iterative Closest Point)算法对无人机航摄桥梁点云1与地面激光扫描桥梁点云数据2进行配准融合,加密后的桥梁点云用于建立运营铁路双线特大桥精细化三维实景建模。提出基于KD-tree的PCA(Principal Component Analysis)算法完整提取出桥梁吊索点云,运用最小二乘法拟合出桥梁拱轴线线形、RANSAC算法拟合出桥面线形。通过与单一无人机、单一地面激光扫描精度及完整性对比分析,以验证融合建模的有效性。研究结果表明:融合建模的模型水平精度1.71 cm、垂直方向精度1.25 cm,较单一无人机建模精度在水平与竖直方向分别提升16.59%与20.89%;融合建模的完整性为98.17%,纹理效果更加真实,并检查出桥墩存在蜂窝麻面、渗水等病害,拱肋存在涂装锈蚀、破裂等病害。该研究可为桥梁三维点云模型应用研究提供思路参考,具有较好的应用前景。

三维激光扫描技术在历史建筑测绘中的应用——以闽清县历史建筑测绘建档项目为例

历史建筑作为城市的文脉,承载着一座城市的历史,受各种因素影响遭受不断的侵蚀甚至灭失,其保护形势越来越严峻。文章以闽清县历史建筑保护测绘为例,采用三维激光扫描技术,结合无人机倾斜摄影技术,对历史建筑真彩色三维点云模型建设进行了探索研究,为历史建筑的测绘资料建档和文物保护工作积累了宝贵的技术经验。结语对该技术进行了总结分析,认为三维激光扫描技术不仅能大幅提升工作效率和测量成果精度,还可实现历史建筑三维可视化,具有广阔的应用前景。

基于车载三维激光扫描的城市道路竣工测量探讨

车载三维激光扫描系统融合了多种传感器和数据源,可以自动、迅速地获取道路的全方位信息。其扫描速度迅捷、数据信息丰富、精确度高、采集过程安全简单,并能节省人力。此技术显著提高了外业生产效率,并降低了生产成本。对车载三维激光扫描技术在道路工程竣工测量中的内外业处理流程的研究结果表明:该技术的精度可达到1∶500测图精度要求,满足城市高架路竣工规划测绘的精度需求。该技术方案是切实可行的,且能高效地提高生产效率。

基于点云的多源数据融合技术

三维激光扫描技术是一门逆向工程应用技术,凭借其高速、全面且高自动化的特点,显示出了强大的不可替代性。三维点云数据有着其多样化、精度高、数据完整的优点。多源数据融合技术使不同设备获取的点云数据、影像数据、空载数据能够相互弥补,提高不同场景环境下的作业效率,完善数据的结构和精度质量,使空、地、水下三维数据的一体化成为可能。通过对不同射程多台三维激光扫描仪的数据进行相对精度分析、调整和融合,并对不同融合方法获取的多源融合数据进行精度验证,探索一种多源数据融合的方法,形成多源数据融合的通用技术流程。为多种载体三维激光扫描技术的数据和影像数据的融合方法研究奠定基础。

三维激光扫描与BIM技术融合的城市轨道交通地下建筑物三维建模方法

本文将三维激光扫描技术与BIM技术相结合,实现了城市轨道交通地下车站、隧道及附属设施的三维建模。通过激光扫描仪获取点云数据,利用点云处理软件进行预处理,包括拼接、去噪和精简等操作;然后利用特征点云提取方法结合BIM建模软件和可视化编程技术,有效解决了传统测绘方法无法获取和处理复杂地下建筑物信息及BIM模型中信息孤岛问题。本文方法对未来城市轨道交通工程建设和运维管理的信息化和三维可视化具有重要意义。