Application of 3D Scanned Big Data of Large-scale Cultural Heritage Objects Based on Noise-robust Transparent Visualization

Three-dimensional(3D) scanning technology has undergone remarkable developments in recent years.Data acquired by 3D scanning have the form of 3D point clouds.The 3D scanned point clouds have data sizes that can be considered big data.They also contain measurement noise inherent in measurement data.These properties of 3D scanned point clouds make many traditional CG/visualization techniques difficult.This paper reviewed our recent achievements in developing varieties of high-quality visualizations suitable for the visual analysis of 3D scanned point clouds.We demonstrated the effectiveness of the method by applying the visualizations to various cultural heritage objects.The main visualization targets used in this paper are the floats in the Gion Festival in Kyoto(the float parade is on the UNESCO Intangible Cultural Heritage List) and Borobudur Temple in Indonesia(a UNESCO World Heritage Site).

New sigma point filtering algorithms for nonlinear stochastic systems with correlated noises

New sigma point filtering algorithms,including the unscented Kalman filter(UKF) and the divided difference filter(DDF),are designed to solve the nonlinear filtering problem under the condition of correlated noises.Based on the minimum mean square error estimation theory,the nonlinear optimal predictive and correction recursive formulas under the hypothesis that the input noise is correlated with the measurement noise are derived and can be described in a unified framework.Then,UKF and DDF with correlated noises are proposed on the basis of approximation of the posterior mean and covariance in the unified framework by using unscented transformation and second order Stirling's interpolation.The proposed UKF and DDF with correlated noises break through the limitation that input noise and measurement noise must be assumed to be uncorrelated in standard UKF and DDF.Two simulation examples show the effectiveness and feasibility of new algorithms for dealing with nonlinear filtering issue with correlated noises.

Three-dimensional(3D)parametric measurements of individual gravels in the Gobi region using point cloud technique

Gobi spans a large area of China,surpassing the combined expanse of mobile dunes and semi-fixed dunes.Its presence significantly influences the movement of sand and dust.However,the complex origins and diverse materials constituting the Gobi result in notable differences in saltation processes across various Gobi surfaces.It is challenging to describe these processes according to a uniform morphology.Therefore,it becomes imperative to articulate surface characteristics through parameters such as the three-dimensional(3D)size and shape of gravel.Collecting morphology information for Gobi gravels is essential for studying its genesis and sand saltation.To enhance the efficiency and information yield of gravel parameter measurements,this study conducted field experiments in the Gobi region across Dunhuang City,Guazhou County,and Yumen City(administrated by Jiuquan City),Gansu Province,China in March 2023.A research framework and methodology for measuring 3D parameters of gravel using point cloud were developed,alongside improved calculation formulas for 3D parameters including gravel grain size,volume,flatness,roundness,sphericity,and equivalent grain size.Leveraging multi-view geometry technology for 3D reconstruction allowed for establishing an optimal data acquisition scheme characterized by high point cloud reconstruction efficiency and clear quality.Additionally,the proposed methodology incorporated point cloud clustering,segmentation,and filtering techniques to isolate individual gravel point clouds.Advanced point cloud algorithms,including the Oriented Bounding Box(OBB),point cloud slicing method,and point cloud triangulation,were then deployed to calculate the 3D parameters of individual gravels.These systematic processes allow precise and detailed characterization of individual gravels.For gravel grain size and volume,the correlation coefficients between point cloud and manual measurements all exceeded 0.9000,confirming the feasibility of the proposed methodology for measuring 3D parameters of individual gravels.The proposed workflow yields accurate calculations of relevant parameters for Gobi gravels,providing essential data support for subsequent studies on Gobi environments.

Noise degradation system using Wiener filter and CORDIC based FFT/IFFT processor

On augmentation of past work, an effective Wiener filter and its application for noise suppression combined with a formed CORDIC based FFT/IFFT processor with improved speed were executed. The pipelined methodology was embraced for expanding the execution of the system. The proposed Wiener filter was planned in such an approach to evacuate the iteration issues in ordinary Wiener filter. The division process was supplanted by a productive inverse and multiplication process in the proposed design. An enhanced design for matrix inverse with reduced computation complexity was executed. The wide-ranging framework processing was focused around IEEE-754 standard single precision floating point numbers. The Wiener filter and the entire system design was integrated and actualized on VIRTEX 5 FPGA stage and re-enacted to approve the results in Xilinx ISE 13.4. The results show that a productive decrease in power and area is developed by adjusting the proposed technique for speech signal noise degradation with latency of n/2 clock cycles and substantial throughput result per every 12 clock cycles for n-bit precision. The execution of proposed design is exposed to be 31.35% more effective than that of prevailing strategies.

The Numerical Simulation of Aerodynamic Noise Generated by CRH3 Train’s Head Surface

In order to solve the increasingly serious problem of railway noise which caused by the train’s speed-up, especially the problem of the dominant aerodynamic noise of the high-speed train, it’s necessary to have a numerical simulation analysis for the CRH3 train’s three dimensional flow model. Setting monitoring points in the positions that the surface curvature changes significantly, using the Large Eddy Simulation Method (LES) to have a transient simulation for the CRH3 train which is in the speed of 300 km/h and 350 km/h, applying the acoustics theory of Lighthill-Curle to predict the aerodynamic noise caused by the head of the CRH3 train. The generation and distribution of the train’s aerodynamic noise are analyzed, so as to provide some reasonable suggestions for the design of the train body.

A Tree Formulation for Signaling Games with Noise

The paper provides an analysis of a sender-receiver sequential signaling game. The private information of the sender is transmitted with noise by a Machine, i.e. does not always correctly reflect the state of nature. Hence, a truthful revelation by the sender of his information does not necessarily imply that the signal he sends is correct. Also, the receiver can take a correct action even if the sender transmits an incorrect signal. The payoffs of the two players depend on their combined actions. Perfect Bayesian Equilibria which can result from different degrees of noise is analysed. The Bayesian updating of probabilities is explained. The fixed point theorem which makes the connection with the idea of rational expectations in economics is calculated. Given a number of equilibria, we comment on the most credible one on the basis of the implied payoffs for both players. The equilibrium signals are an example of the formation of a language convention discussed by D. Lewis.

Design of RLS Wiener Smoother and Filter for Colored Observation Noise in Linear Discrete-Time Stochastic Systems

Almost estimators are designed for the white observation noise. In the estimation problems, rather than the white observation noise, there might be actual cases where the observation noise is modeled by the colored noise process. This paper examines to design a new estimation technique of recursive least-squares (RLS) Wiener fixed-point smoother and filter for colored observation noise in linear discrete-time wide-sense stationary stochastic systems. The observation y(k) is given as the sum of the signal z(k)=Hx(k) and the colored observation noise vc(k). The RLS Wiener estimators explicitly require the following information: 1) the system matrix for the state vector x(k);2) the observation matrix H;3) the variance of the state vector x(k);4) the system matrix for the colored observation noise vc(k);5) the variance of the colored observation noise;6) the input noise variance in the state equation for the colored observation noise.

结合载客热点和POI的出租车停车位划定方法

针对出租车随意停靠造成城市交通拥堵甚至交通事故的问题,利用成都实际区域的出租车GPS(Global Position System)数据和爬取的POI(Point of Interest)数据,使用DBSCAN(Density-Based Spatial Clustering of Application with Noise)聚类算法对上下客点进行聚类,得到出租车的载客热点,根据POI的类型划定载客热点区域的类型,对出租车不同时间的出行需求进行分析,进而划分出出租车的固定停车区域。研究结果表明,出租车固定停车区域的设定与出行者的出行需求有关,即将固定停车区域设置在出行者出行需求多的区域,可以满足出行者的不同出行需求。结合出租车载客热点和爬取POI数据划定固定停车区域的方法具有较高的实用性,可为城市交通安全方面提供理论和现实意义。

超长空间激光传输数值模拟研究进展

文章主要围绕空间引力波探测中超长空间链路传输部分进行介绍,概述了目前国内外星间传输仿真时采用的计算方法,以及指向抖动引起的相位噪声分析方法。相较于地基引力波探测,空间引力波探测可以有效降低噪声,增加干涉臂长度,从而实现更高精度、更低频率的探测。在长达数百万公里的传输距离,以及皮米量级数值模拟的精度要求下,需要考虑指向角变化引起的相位噪声。研究表明,在2.5×10~9 m的传输距离下,离焦和像散是影响指向抖动噪声的主要像差。通常情况下,相位驻点位置与原点位置存在一定偏离,需要对望远镜角度进行调整,才能使相位噪声最小化。在相位驻点位置进行引力波探测,可以有效降低相位噪声,并降低望远镜出瞳波前的质量要求。而大的离焦像差与小的彗差可以使相位驻点接近光轴,提高接收到的激光功率。

基于非完整点云法线滤波补偿的散货船舶舱口识别算法

自动装船系统是智能化港口建设的重要组成部分,能够大幅降低港口作业成本,提高经济效益。舱口识别作为自动装船任务的首要环节,成功率和识别精度是后续任务顺利进行的重要保障。由于港口激光雷达的数目和角度等问题,采集所得船舶点云数据时常出现缺失;此外船舶舱口附近经常有大量物料堆积,会使采集到的点云数据无法准确表达舱口的几何信息。由于上述港口实际装船作业中时常出现的问题,显著降低了现有算法的识别成功率,对自动装船作业造成了不良影响,因此迫切需要提升在船舶点云中存在物料干扰或舱口数据缺失的情况下的舱口识别成功率。基于船舶结构特征与自动装船过程中采集的点云数据分析,提出了基于非完整点云法线滤波补偿的散货船舶舱口识别算法。在使用港口实际采集点云所制作的数据集上进行了实验验证,识别成功率和识别精度较Miao和Li的舱口识别算法相比均有提升。实验结果表明,所提算法既能对舱口内物料噪声进行滤除,又能对数据缺失部分进行补偿,能够有效提升舱口识别效果。

连拱隧道中导洞不同起爆位置振动效应研究

为研究隧道掘进爆破炮孔不同起爆位置振动效应,在连拱隧道中导洞开挖过程中开展相关试验研究,并基于CEEMDAN-小波包对监测到的爆破振动信号进行降噪处理。研究表明:1)采用CEEMDAN-小波包法对爆破振动信号进行去噪,重构,能有效保留爆破振动信号真实信息;2)炮孔不同起爆位置质点峰值振速,反向起爆>中间起爆>正向起爆;振动频率大小范围,正向起爆>反向起爆>中间起爆,其中正向起爆的频率分布更广,且具有多个峰值,有利于能量朝高频转移;3)对重构后的爆破振动信号进行Hilbert变换,发现隧道掏槽段爆破瞬时能量关系为:反向起爆>中间起爆>正向起爆;随着雷管段别的增加,反向起爆和正向起爆波形较宽、质点峰值振速较大,中间起爆振动波形较窄、质点峰值振速较小;4)对比分析炮孔不同起爆位置破岩块度,反向起爆更为均匀,效果最佳。

基于深度学习的多视图火焰面三维重建

针对火焰面三维重建时存在背景噪点的问题,提出了一种基于MVSNet多视图三维重构网络的IM-MVSNet网络用于重构层流火焰的火焰面。该网络通过对输入采样图像的参考帧以及邻域帧进行图像分割,去除采样时的背景噪声,得到高质量分割图像,然后将多视图图像进行三维重建,构建层流火焰面三维点云,进而得到重构的层流火焰面。通过不同重构模型火焰面重构效果对比,本文提出的三维重构网络能够有效减少重构火焰面的点云噪点,提高火焰面重构精度,为燃烧研究提供了一种新的方法。

一种基于目标点云分布特性的动态聚类算法

激光雷达在自动驾驶系统的目标检测任务中发挥着重要作用,但其扫描机理会使得点云分布不均匀,常规聚类算法由于参数固定会导致较多的错误聚类。为解决该问题,该文以椭圆形状作为邻域空间,设计基于采样点位置的邻域自适应调整策略,提出一种基于目标点云分布特性的动态聚类算法。通过正确聚类、过聚类等综合结果评估算法的性能,在KITTI数据集上进行了数值分析得到算法参数,并在校园环境中进行了实车对比实验。结果表明:所提算法能减少基于密度的噪声应用空间聚类(DBSCAN)中固定邻域所造成的70.60%过聚类、49.76%欠聚类等错误结果,从而有效提高算法的综合聚类性能。

基于改进DBSCAN的星载激光雷达数据多尺度滤波研究

星载激光雷达数据滤波过程易受复杂背景、粗差点、噪声点等问题的干扰,导致滤波效果大幅度下降,所以研究基于改进DBSCAN的星载激光雷达数据多尺度滤波方法。采用改进DBSCAN算法对星载激光雷达数据做聚类处理,并标记噪声点,通过半球形邻域算法提取点云数据特征。根据提取到的点云数据特征构建规则格网,通过格网的多路径效应剔除点云数据中的粗差点与噪声点,完成星载激光雷达数据多尺度滤波。实验结果表明,所提方法的星载激光雷达数据多尺度滤波误差较低、滤波效果好,实际应用价值较高。

基于分数阶偏微分的数字图像滤波去噪仿真

受多种因素影响,数字图像会呈现出不同程度的噪声图斑,导致图像质量、清晰度降低,加大了图像分析、检测、分割等难度,为此,提出基于偏微分方程的图像自适应滤波去噪算法。区分图像噪声点和非噪声点,检测图像的边缘特征,提高算法对边缘的保留能力;构建分数阶偏微分方程模型,通过模型完成对图像的自适应滤波去噪处理。选取含有不同程度的噪声图像对所提方法展开实验测试,结果表明,所提方法可以有效去除图像中的冗余噪声,使图像整体质量得到大幅度提升。

北斗观测数据质量及动态PPP性能分析

为分析北斗卫星导航系统(BeiDou Navigation Satellite System,BDS)在全球范围内的数据质量、动态精密单点定位(precise point positioning,PPP)性能及不同区域内的性能差异,选取三个不同区域内共9个多GNSS实验(Multi-GNSS Experiment,MGEX)连续跟踪站的观测数据,以GPS为参考,从卫星可见性、伪距多路径效应、数据完整率、信噪比(signal-to-noise ratio,SNR)及PPP定位精度五个方面对BDS的数据测质量以及定位精度进行分析.结果表明:BDS的卫星可见性具有区域差异,多路径效应及SNR并没有呈现出区域特征,其中北斗三号(BeiDou-3Navigation Satellite System,BDS-3)的数据质量优于北斗二号(BeiDou-2 Navigation Satellite System,BDS-2)的,且BDS不同频点的数据质量也有明显差异,B1I频点数据质量较差. BDS的动态定位精度略弱于GPS,多系统对提高定位精度具有显著的效果.

基于OPAX的驾驶舱内结构噪声传递路径研究

对车内结构噪声进行合理降噪的有效方法是阻断振动能量传递最大的路径,为此建立传递路径模型并进行噪声贡献量分析。首先,基于发动机舱内机械构造规划出由振源到驾驶舱的多级传递路径,并在振动能量传递的连接点处设置路径拐点;然后,采用扩展工况传递路径分析(operational path analysis with exogeneous inputs,OPAX)方法确定路径中各拐点对车内噪声的贡献量,并将噪声拟合值与实测值进行分析对比。结果表明,不同路径拐点对车内结构噪声影响明显不同,其中橡胶悬置拐点对车内噪声影响最大,该处噪声拟合值与实测值也最为接近,噪声峰值达到63.5 dB,副车架拐点对车内噪声影响次之,噪声峰值为53.2 dB,排气吊耳拐点对车内噪声影响较小,噪声峰值仅为38.7 dB。采用本文方法可有效确定对车内结构噪声影响最大的路径。

点云密度特征约束下的隧道开挖轴线抗噪提取

三维激光扫描仪获取的隧道原始点云数据往往包含大量的无关点,这对隧道轴线的提取有较大的影响,同时较难满足现场施工的实时性需求。针对上述问题,本文将考虑隧道点云密度特征,提出一种高效、自动的隧道中轴线提取方法。首先,统计隧道点云的密度特征,依据不同密度的点云区域,判别其点云特征,生成不同的约束系数,并将约束系数作为轴线拟合点的选取依据;其次,经过俯视投影和RANSAC处理,得到投影平面中轴线;然后,经过侧视投影得到拱顶位置,依据拱顶位置将中轴线调整至隧道中心处;最后,利用RANSAC线性拟合以实现对不同区段轴线的预测。结果表明,本文方法根据指定区域的隧道点云密度特征,能够快速、准确提取带有大量噪声的隧道点云中轴线,且适用于不同区段的开挖隧道,具有较好的适应性。

孝感市城市区域噪声点位调整数据复盘及建议

孝感市“十四五”城市环境噪声已经完成两个周期年,以2020年为基准年,通过2021年和2022年两年的监测数据分析发现的问题,为后期调整做出参考。通过聚焦分析数据正态分布特征,从调整后区域噪声、功能区噪声数据一致性以及监测点位数量优化三方面展开分析。分布特征分析表明,调整后数据正态分布特征明显强化,说明调整后的布点更适合不断发展变大的城市规模。从深入的数据比对分析也发现了有关布点方面存在的问题,主要是区域噪声和功能区噪声布点在第3类功能区网格点上设置的差异以及来自交通噪声对区域噪声的干扰。因此,应该避免布点出现上述两个方面的问题,对于3类功能区网格中工业占地面积的比例超过50%,做出了相关讨论。复盘发现点位设置存在功能区类别覆盖不全的问题,根据当前分布特征和现状统计标准差为6.0的条件,适用数理统计公式推算了可以相应减少监测点位数量。

恩施市区域噪声现状评价及其自动监测点位优化

为掌握恩施市城市区域环境噪声污染状况,更好地改善和提高声环境质量。对恩施市区2021-2022年区域环境噪声进行了监测与分析,评价了恩施市区环境噪声现状。在2021恩施市区域噪声点位调整后,通过对2021-2022年来噪声监测数据统计评价和聚类分析,发现较2021年,2022年的区域声环境质量有所减弱。从115个监测点位中选取17个作为区域噪声自动监测点位推荐选址,根据优化后的区域噪声监测点位建设自动监测系统后,可实时掌握区域噪声水平及其变化情况,使得监测效率大幅提高。为此,在今后的噪声监测中,应根据《城市声环境质量监测技术规范》《声环境质量标准》等来规范监测点,并运用多种方法实现功能区噪声监测点位优化布设。