Research on 3D Laser Scanning Reconstruction of Ancient Buildings Combined with BIM Technology

After more than 30 years of scientific and social development, surveying and mapping technology by leaps and bounds, engineering surveying technology has undergone tremendous changes. In the process of protecting ancient buildings, it is necessary to obtain the precise dimensions of architectural details. In this study, the path of 3D laser scanning combined with BIM technology is explored. Taking the observation and protection of the ancestral hall of the Liu family as an example, this study aims to draw drawings that reflect the relevant information about the ancient buildings, the accurate three-dimensional model of ancient buildings is established with BIM technology, which provides new methods and ideas for the research and protection of ancient buildings. .

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.

Large-scale deformation monitoring in mining area by D-InSAR and 3D laser scanning technology integration

Large-scale deformation can not be detected by traditional D-InSAR technique because of the limit of its detectable deformation gradient,we propose a method that combines SAR data with point cloud data obtained by 3D laser scanning to improve the gradient of deformation detection.The proposed method takes advantage of high-density of 3D laser scanning point cloud data and its high precision of point positioning after 3D modeling.The specifc process can be described as follows:frst,large-scale deformation points in the interferogram are masked out based on interferometric coherence;second,the interferogram with holes is unwrapped to obtain a deformation map with holes,and last,the holes in the deformation map are flled with point cloud data using inverse distance weighting algorithm,which will achieve seamless connection of monitoring region.We took the embankment dam above working face of a certain mining area in Shandong province as an example to study large-scale deformation in mining area using the proposed method.The results show that the maximum absolute error is 64 mm,relative error of maximum subsidence value is 4.95%,and they are consistent with leveling data of ground observation stations,which confrms the feasibility of this method.The method we presented provides new ways and means for achieving large-scale deformation monitoring by D-InSAR in mining area.

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.

Research on wind erosion processes and controlling factors based on wind tunnel test and 3D laser scanning technology

The study of wind erosion processes is of great importance to the prevention and control of soil wind erosion.In this study,three structurally intact soil samples were collected from the steppe of Inner Mongolia Autonomous Region,China and placed in a wind tunnel where they were subjected to six different wind speeds(10,15,17,20,25,and 30 m/s)to simulate wind erosion in the wind tunnel.After each test,the soil surfaces were scanned by a 3D laser scanner to create a high-resolution Digital Elevation Model(DEM),and the changes in wind erosion mass and microtopography were quantified.Based on this,we performed further analysis of wind erosion-controlling factors.The study results showed that the average measurement error between the 3D laser scanning method and weighing method was 6.23%for the three undisturbed soil samples.With increasing wind speed,the microtopography on the undisturbed soil surface first became smooth,and then fine stripes and pits gradually developed.In the initial stage of wind erosion processes,the ability of the soil to resist wind erosion was mainly affected by the soil hardness.In the late stage of wind erosion processes,the degree of soil erosion was mainly affected by soil organic matter and CaCO_(3)content.The results of this study are expected to provide a theoretical basis for soil wind erosion control and promote the application of 3D laser scanners in wind erosion monitoring.

The Research Application of 3D Laser Scanning Technology in the Deformation Detection of Large Cylindrical Oil Tank

In order to ensure the safety in using a large cylindrical storage tank,it is necessary to regularly detect its defonnatioii.The traditional total station method has high accuracy in determining the deformation,however,it has a low measxirement efficiency.Long-term observation means,there are more risks in the petrochemical plant,therefore,this paper proposes the usage of the 3D laser scanner,replacing the traditional total station to determine the defbnnation of a large cylindrical storage tank.The Matlab program,is compiled to calculate the point cloud data,while the tank deformation is analyzed from two different points which are,the local concave convex degree and the ovality degree.It is concluded that,the difference between the data obtained by 3D laser scanning,and total station is within the range of oil tank deformation limit,therefore,3D laser scanner can be used for oil tank deformation detection.

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。

融合自注意力与残差神经网络的3D打印激光在机测量误差修正方法

激光测量能够实现高效地非接触实时测量,被广泛应用于3D打印领域,但激光测量容易受测量条件、外部环境等多种因素的干扰,这些因素错综复杂,难以量化分析。为此,结合直射式激光三角测量原理,在分析测量精度影响因素的基础上,提出了一种基于融合自注意力和残差神经网络的3D打印在机测量误差修正方法。首先,将影响测量精度的因素作为输入变量,采集激光测量值,得到样本数据集;然后利用残差网络提取出样本数据的深层次特征,并引入自注意力机制建立影响因素之间的联系,得到带权重的提取特征;再通过全连接网络对带权重特征进行学习,得到测量误差的预测值,基于该预测值完成对测量误差的修正。自主搭建了一套激光在机测量系统,采用红、绿、紫3种同材质彩色卡纸进行实验验证。结果表明,所提的方法与卷积神经网络和自注意力神经网络相比,均方误差、均方根误差和平均绝对误差均最小,稳定性最好,修正结果最接近真实值;对激光测量结果进行校正后,使其误差由原来的±28μm减小到±9μm以下,显著提高了3D打印激光在机测量的精度和稳定性。

3D打印-激光烧结制备导体和介质厚膜的显微结构与性能

为拓展3D打印技术在厚膜混合集成电路制备领域的应用,提高厚膜浆料烧结效率,采用3D直写+激光烧结制备三种导体浆料厚膜和一种介质浆料厚膜,并与常规的丝网印刷+高温炉烧结厚膜进行显微结构与性能的对比研究。结果表明,常规丝网印刷+高温炉烧结的导体及介质厚膜具有良好的显微结构与性能。相比而言,3D直写+激光烧结制备的导体厚膜平整连续、厚度均匀,焊接性能良好,但结构不够致密,部分导体厚膜存在膜层附着力不足,方阻偏大的问题;介质厚膜激光烧结后的致密性较导体厚膜更低,绝缘性能不满足要求。3D直写制备导体或介质浆料厚膜具有可行性,但激光烧结工艺参数有待优化,以实现厚膜的烧结致密化,提高厚膜与基板的结合强度。

基于PROA-BP的激光3D投影振镜偏转电压预测模型

为减小激光3D投影系统振镜偏转角偏差与根据振镜偏转角标定的转轴公垂线长度e误差引起的投影系统综合非线性误差,实现激光3D投影系统高精度辅助装配,提出一种基于改进的?鱼优化算法-BP神经网络的激光3D投影振镜偏转电压预测模型,以激光出射方向单位矢量作为输入预测振镜偏转电压数值。将改进的?鱼算法与BP神经网络相结合,解决BP神经网络容易陷入局部最优解问题,并通过BP神经网络实现激光3D投影系统综合非线性误差的耦合与补偿。结果表明,改进的?鱼算法-BP神经网络训练10 000次后均方差误差和平均绝对误差均值分别是粒子群算法-BP神经网络的41.2%、62.4%,是BP神经网络的22.2%、50.7%。基于改进的?鱼算法-BP激光3D投影振镜偏转电压模型的投影定位精度为0.35 mm,与激光3D投影传统模型相比,投影定位精度提升了30%,可实现更高精度投影定位。

智能激光3D投影空间目标辐射照度校准技术

由于激光3D投影系统的光路复杂,且受空间目标的形状和大小的影响,导致在特定空间内难以取得理想的投影效果,使得投影目标与实际投影点之间存在较大的偏差,因此,提出一种辐射照度校准方法。分别利用矩形、圆形两种不同形状的辐射面和敏感面搭建辐射照度测量仪,得到4种不同辐射照度测量结果;利用斯忒藩-玻尔兹曼全辐射定律,对测量结果校准,进而完成对智能激光3D投影空间目标辐射照度的校准。实验结果表明,所提方法辐射照度校准结果与实际结果基本一致,且辐射照度校准误差保持在6 W·m^(2)以内。

3D激光扫描技术在不动产测绘中的应用与挑战

利用3D激光扫描技术,通过发射激光到目标物体并接收反射光来获取精确的三维数据。这项技术以其高精度、高速度和能够捕捉复杂结构的优势,正在不动产测绘领域中发挥重要作用。在建筑物三维建模、宗地测量和房屋测绘等应用中,3D激光扫描展现了其独特的优势。然而,3D激光扫描技术的应用面临数据处理难度大、扫描精度受限、成本较高和技术普及度不足等挑战。

三维激光扫描技术结合3DS MAX在建筑物逆向建模中的应用

针对目前建筑物逆向建模中存在的数据采集效率低、模型精度低、模型效果不真实等问题,提出了一种三维激光扫描技术结合3DS MAX对建筑物进行逆向建模的方法。使用架站式三维激光扫描仪对目标建筑物进行多站扫描,利用SCENE软件对多站点云数据进行配准、去噪生成三维点云,基于三维点云生成建筑物各立面的正射影像,将影像导入AutoCAD并绘制建筑物二维平立面矢量图,将各平立面矢量图导入3DS MAX软件,经建立白模、纹理贴图等过程,生成目标建筑三维模型,最后对模型的精度进行了验证。结果表明,该方法可以高效地建立高精度且具有逼真效果的建筑物三维模型。

3D打印用聚丙烯粉末材料的性能研究

选择性激光烧结(SLS)是一种基于粉末床的激光增材制造技术,无需夹具和模具,可成型具有复杂结构的制件,制件自由设计度高、适用于定制化小批量生产,新产品开发成本低、制造周期短。高分子材料是应用最早、最广泛的激光烧结成型材料,具有表面能低、熔融指数高、烧结温度低、所需激光功率小等优点。该研究以聚丙烯高分子粉末为原粉,通过抗氧性能优化,筛选出适合的配方,将其用于SLS型3D打印,并与市售商品进行对比分析。结果表明,该粉末与市售的选择性激光烧结型3D打印用聚丙烯粉末均可成功打印出标准测试样条,且经粒度分布、SEM、DSC、TG、力学性能等对比分析发现,该粉末收缩性更低、可成型性和热稳定性更好、刚性更高。

3D激光扫描仪在弹性柱体对接系统的应用算法研究

在特殊工程应用场合,需将弹性柱体装填至另一刚性柱体中,其核心是2个部件同轴度的误差控制。弹性柱体采用特殊的包覆工艺,表面起伏不平,因此,数据采集方式的选择非常关键,同时,数据处理也会影响同轴度误差。设计了一套自动对接系统,采用3D激光扫描仪采集数据,并选择最小二乘法及循环比较法算法拟合曲线。结果表明,该系统效果良好。

基于激光视觉的3D舞美虚拟人物影像自动化识别系统

针对3D舞美虚拟人物影像易受到成像条件干扰,导致人物姿态识别误差大的问题,设计基于激光视觉的3D舞美虚拟人物影像自动化识别系统。使用线结构光视觉三维测量装置,采集表演人物的激光视觉图像后,以平行投影的方式,重构3D舞美虚拟人物影像;通过基于谱系聚类的关键姿态轮廓特征提取方法,提取影像中关键姿态轮廓特征,输入基于HCRF的3D舞美虚拟人物影像人体姿态识别模型,计算人体姿态动作类型的条件概率,实现3D舞美虚拟人物影像自动化识别。实验结果表明,该系统对3D舞美虚拟人物影像中,行走、跑步、跳跃、跌倒、身体倾斜五种姿态类型自动化识别后,识别结果的交并比最小值为0.986,识别结果与真实姿态动作类型匹配。

基于网版铺粉及激光打标平台的金属锡3D打印研究

金属3D打印技术是目前增材制造研究的重点和热点。研究使用YLP-DF30激光打标机平台进行金属锡的立体打印,并利用合适网目数的网版完成铺粉工序,通过对3D打印各工艺参数的优化,得到了良好成型的金属锡3D打印成品,并利用显微镜分析观察了打印结果。结果表明,激光打标设备功率为25W,速度为5.00mm/s时打印出来的成品呈现出较好光泽,并且具有良好的致密程度及成型。

SLM3D打印技术与失蜡铸造技术在可摘局部义齿支架制作中的应用

目的分析选择性激光熔融(SLM)3D打印技术与失蜡铸造技术在可摘局部义齿支架制作中的应用效果。方法选取2021年5月至2023年5月汉中市口腔医院收治的86例KennedyⅠ类牙列缺损患者作为研究对象,根据随机数表法将患者分为A组和B组各43例。A组采用SLM3D打印技术行可摘局部义齿支架制作,B组采用失蜡铸造技术行可摘局部义齿支架制作。两组患者于义齿佩戴1周后复诊,比较两组患者口腔内黏膜压痛点数量、义齿支架佩戴效果以及咀嚼效率;两组患者于义齿佩戴1个月后再次复诊,比较两组患者的满意度评分、主观感受评分及并发症发生情况。结果义齿佩戴1周后,A组患者口腔内黏膜平均压痛点为(0.61±0.13)个,明显少于B组的(2.23±0.21)个,A组患者吸光度值为0.61±0.05,明显高于B组患者的0.43±0.03,差异均有统计学意义(P<0.05);义齿佩戴1周后,A组患者的固位性、适合性和稳定性分别为55.81%、53.49%、58.14%,明显高于B组的30.23%、27.91%、32.56%,差异均有统计学意义(P<0.05);义齿佩戴1个月后,A组患者的主观感受评分和满意度评分分别为(28.07±2.75)分、(14.66±3.21)分,明显高于B组患者的(16.55±0.44)分、(6.68±1.32)分,差异均有统计学意义(P<0.05);义齿佩戴1个月后,A组患者的并发症总发生率为6.98%,明显低于B组患者的23.26%,差异有统计学意义(P<0.05)。结论SLM3D打印技术在可摘局部义齿支架制作中的应用效果良好,制作义齿支架较传统失蜡铸造技术偏差更小,具有更高的精确度,同时患者使用舒适度和满意度也更高,值得临床推广应用。

Towards in-situ diagnostics of multi-photon 3D laser printing using optical coherence tomography

In recent years,multi-photon 3D laser printing has become a widely used tool for the fabrication of micro-and nanostructures for a large variety of applications.Typically,thorough sample characterisation is key for an efficient optimisation of the printing process.To date,three-dimensional microscopic inspection has usually been carried out on finished 3D printed microstructures,that is,using ex-situ approaches.In contrast,in-situ 3D characterization tools are desirable for quickly assessing the quality and properties of 3D printed microstructures.Along these lines,we present and characterise a Fourier-domain optical coherence tomography(FD-OCT)system that can be readily integrated into an existing 3D laser lithography setup.We demonstrate its capabilities by examining different 3D printed polymer microstructures immersed in a liquid photoresist.In such samples,local reflectivity arises from the(refractive-index)contrasts between the polymerised and non-polymerised regions.Thus,the refractive index of the printed material can be extracted.Furthermore,we demonstrate that the reflectivity of polymer-monomer transitions exhibits time-dependent behaviour after printing.Supported by transfer-matrix calculations,we explain this effect in terms of the time-dependent graded-index transition originating from monomer diffusion into the polymer matrix.Finally,we show exemplary 3D reconstructions of printed structures that can be readily compared with 3D computer designs.

An approach to form the dome shape by 3D laser forming

Application of a thermal source in non-contact forming of sheet metal is known for some time. Replacement of this thermal source with a laser beam promises the much greater controllability of the process. To date, research focuses on dealing with rectangular plates, and only a few studies are presented for axis-symmetric geometries like circular plates. This study presents the work to get the dish or bowl shape by an initially flat circular plate. Two different scanning strategies circular and radial are attempted to get the desired dish shape. Following the unexpected distortion throughout the plate, a second series of experiments are conducted on a wide range of specimen geometries. An interesting phenomenon is observed. It is suggested that homogeneous dissemination of heat along with combined form of both of the scanning strategies, could have more potential to form dome shape.