Reconstruction of 3-D digital cores using a hybrid method

A 3-D digital core describes the pore space microstructure of rocks. An X-ray micro CT scan is the most accurate and direct but costly method to obtain a 3-D digital core. In this study, we propose a hybrid method which combines sedimentation simulation and simulated annealing （SA） method to generate 3-D digital cores based on 2-D images of rocks. The method starts with the sedimentation simulation to build a 3-D digital core, which is the initial configuration for the SA method. We update the initial digital core using the SA method to match the auto-correlation function of the 2-D rock image and eventually build the final 3-D digital core. Compared with the typical SA method, the hybrid method has significantly reduced the computation time. Local porosity theory is applied to quantitatively compare the reconstructed 3-D digital cores with the X-ray micro CT 3-D images. The results indicate that the 3-D digital cores reconstructed by the hybrid method have homogeneity and geometric connectivity similar to those of the X-ray micro CT image. The formation factors and permeabilities of the reconstructed 3-D digital cores are estimated using the finite element method （FEM） and lattice Boltzmann method （LBM）, respectively. The simulated results are in good agreement with the experimental measurements. Comparison of the simulation results suggests that the digital cores reconstructed by the hybrid method more closely reflect the true transport properties than the typical SA method alone.

Monitoring slope deformation using a 3-D laser image scanning system: a case study

An ILRIS-36D 3-D laser image scanning system was used to monitor the Anjialing strip mine slope on Pingshuo in Shanxi province. The basic working principles, performance indexes, features and data collection and processing methods are illus-trated. The point cloud results are analyzed in detail. The rescale range analysis method was used to analyze the deformation char-acteristics of the slope. The results show that the trend of slope displacement is stable and that the degree of landslide danger is low. This work indicates that 3-D laser image scanning can supply multi-parameter, high precision real time data over long distances. These data can be used to study the distortion of the slope quickly and accurately.

Parallel computing approach for efficient 3-D X-ray-simulated image reconstruction

Accurate 3-dimensional(3-D)reconstruction technology for nondestructive testing based on digital radiography(DR)is of great importance for alleviating the drawbacks of the existing computed tomography(CT)-based method.The commonly used Monte Carlo simulation method ensures well-performing imaging results for DR.However,for 3-D reconstruction,it is limited by its high time consumption.To solve this problem,this study proposes a parallel computing method to accelerate Monte Carlo simulation for projection images with a parallel interface and a specific DR application.The images are utilized for 3-D reconstruction of the test model.We verify the accuracy of parallel computing for DR and evaluate the performance of two parallel computing modes-multithreaded applications(G4-MT)and message-passing interfaces(G4-MPI)-by assessing parallel speedup and efficiency.This study explores the scalability of the hybrid G4-MPI and G4-MT modes.The results show that the two parallel computing modes can significantly reduce the Monte Carlo simulation time because the parallel speedup increment of Monte Carlo simulations can be considered linear growth,and the parallel efficiency is maintained at a high level.The hybrid mode has strong scalability,as the overall run time of the 180 simulations using 320 threads is 15.35 h with 10 billion particles emitted,and the parallel speedup can be up to 151.36.The 3-D reconstruction of the model is achieved based on the filtered back projection(FBP)algorithm using 180 projection images obtained with the hybrid G4-MPI and G4-MT.The quality of the reconstructed sliced images is satisfactory because the images can reflect the internal structure of the test model.This method is applied to a complex model,and the quality of the reconstructed images is evaluated.

The Parameter Determination in the Design of 3-D Spherically Symmetric FIR Filters via the McClellan Transformation

In the design of 3-D spherically symmetric FIR filters via the McClellan transformation, two methods are proposed to determine the transformation parameters. The first is to improve the original 3-D algorithm by exploiting the 2-D effective methods in 3-D. This method can change the constrained optimization algorithm into the unconstrained one and makes the design easier to realize. The second method is to solve the coupled equations under constrained conditions and a set of ideal parameters can be gotten. The design example shows that the two methods are all efficient and easier than the original algorithm.

Beach Morphology and Sediment Budget Variability Based on High Quality Digital Elevation Models Derived from Field Data Sets

The morphological and volumetric changes of a sandy beach were investigated through a series of two- monthly filed surveys carried out aver a 2-year period from April 2005 to January 2007. This paper discuss the ability of 3-D digital elevation models (DEMs) derived from high accurate data to assess and quantify beach morphodynamics in relation with wave forcing. The methodology and data acquisition are described and consist mainly in the production of interpolated DEMs from which a variety of representations can be made, including as elevation change maps, two-dimensional cross-sections of the beach, calculation of net volume. The results of the analysis highlight seasonal changes in beach morphology due to variations in wave energy. This behavior is characterized by beach erosion and bar decay under high-energy waves and net accretion and bar formation during relatively fair weather conditions. The sand budgets adjustments show that the loss of volume in the winter months is compensated for by accumulation to the beach during summer. This trend suggests that there is a mechanism which controls the beach evolution. The correlation between beach changes and wave energy variations highlights a net relation between them. The results from this in- vestigation state the value of DEMs utilized and demonstrate the efficiency of the 3-D approach employed here to assess the erosion and accretion patterns which would not be visualized using 2-D profiles.

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 .

THREE DIMENSIONAL DIGITIZATION OF HUMAN HEAD BY FUSING STRUCTURED LIGHT AND CONTOURS

Three dimensional digitization of human head is desired in many applications. In this paper, an information fusion based scheme is presented to obtain 3-D information of human head. Structured light technology is employed to measure depth. For the special reflection areas,in which the structured light stripe can not be detected directly, the shape of the structured light stripe can be calculated from the corresponding contour. By fusing the information of structured light and the contours, the problem of reflectance influence is solved, and the whole shape of head,including hair area, can be obtained. Some good results are obtained.

Synthetic aperture radar tomography sampling criteria and three-dimensional range migration algorithm with elevation digital spotlighting

Based on the general geometric model of multi-baseline Synthetic Aperture Radar Tomography （TomoSAR）, the three-dimensional （3-D） sampling criteria, the analytic expression of the 3-D Point Spread Function （PSF） and the 3-D resolution are derived in the 3-D wavenumber domain in this paper. Considering the relationship between the observation geometry and the size of illuminated scenario, a 3-D Range Migration Algorithm with Elevation Digital Spotlighting （RMA-EDS） is proposed. With this algorithm 3-D images of the area of interest can be directly and accurately reconstructed in the 3-D space avoiding the complex operations of 3-D geometric correction. Finally, theoretical analyses and simulation results are presented to demonstrate the shift-varying property of the 3-D PSF and the spatialvarying property of the 3-D resolution and to demonstrate the validity of the 3-D RMA-EDS.

应用三维扫描技术的织物成型性测试与表征

为能够快速、简便、准确测定和评价织物的成型能力,综述织物成型性测试的背景和研究现状,介绍了结构光非接触式三维扫描测量仪的测试原理并以三维扫描技术为基础,提出一种直观且方便的织物成型评价方法。首先使织物试样在顶球的作用下起皱,借助三维扫描获取数字模型,并利用三维处理软件对模型进行处理得到相关指标。对10块试样测试分析发现,织物下的体积空隙率可较好地表征织物成型性,为表征和评价织物的成型能力提供了一种新的思路。

基于二维DR的颅面硬组织与软组织拟合的研究

目的 :以数字化X线摄影片(digital radiograph,DR)图像和激光扫描为数据源,三维重建颅面硬组织和软组织,并进行硬软组织的有效拟合,以期为治疗方案确定、手术方法选择和提高医患交流的水平提供平台。方法:在志愿者面部贴定铅点,拍摄头颅正侧位DR片。利用基于二维DR数据的颅面硬组织三维重建系统进行硬组织形变建模,获得颅面部硬组织模型。利用激光扫描数据进行面部软组织三维重建,获得面部软组织三维模型。然后通过铅点坐标的匹配,将颅面硬组织与面部软组织进行拟合。结果:分别重建了能反映真实颅面部组织结构的硬组织三维模型和面部软组织三维模型,并实现了颅面部硬组织与软组织的有效拟合。结论:本研究实现了颅颌面三维结构的有效重建和拟合,为进一步进行正颌手术模拟和容貌预测奠定了基础。拟合结果真实可靠,能够用于临床。

VOLUMETRIC-SWEPT DISPLAY SYSTEM BASED ON HELIX ROTATING SCREEN AND DMD

Based on the helix rotating screen and the digital micro-mirror device （DMD）, the former proto of volumetric-swept display system is improved. The 3-D display system adopting a helix rotating screen to construct an imaging space meliorate the defects, such as the smaller image space, the fewer voxels and the severer voxel overlap dead zone caused by planar rotating screen. DMD with spatial light modular （SLM） technology increases the transmission bandwidth of 3-D data in the voxel activation subsystem and activate multi-voxel once time. The volumetric-swept system based on helix rotating screen and DMD is developed. The experimental results show that the image space, the vision dead zone, the voxels on slice, and the voxel activation capacity of the designed proto are superior to the plane rotating screen system.

基于Virtools的数字化人体模型仿真运动研究

立足于服装工业对数字化人体模型仿真运动的需求,提出了一种建立人体模型仿真运动的新方法。通过对特定人体的三维扫描数据处理,实现个性化的三维人体NURBS曲面模型重构,再通过设定骨骼IK绑定,完成模型格式转换;通过MotionAnalysis、EvaRT、motionbuilder等,完成仿真场景设置。最后,在Virtools实现数字化模型与行为动作的拟合,完成运动仿真。实验证明,所建立的人体模型仿真运动过程真实性强,具有较高的科研价值。

三维数字化扫描在口腔临床中应用的探究

目的分析口腔临床中应用三维数字化扫描的临床效果。方法选择2016年10月～2018年10月本院收治的口腔义齿修复患者98例进行分组研究,根据随机数表法分为观察组与对照组,每组49例。对照组患者予以石膏灌制模型制作义齿处理,观察组患者予以三维数字化扫描后制作义齿处理。调查患者对取模满意率与义齿适应性,评估临床效果,并比较分析。结果观察组患者对取模满意率明显高于对照组(P <0.05),同时义齿适应性Ⅰ级率上也明显优于对照组(P <0.05),临床总有效率显著高于对照组(P <0.05)。结论三维数字化扫描在口腔临床中有不错的价值,可节省繁琐步骤,减少材料与人工消耗,提高义齿适应性,使得患者对取模更满意,提高义齿修复效果,值得在口腔临床应用。

虚拟服装迁移在个性化服装定制中的应用

为解决服装定制中个性化服装开发效率低以及虚拟试衣过程繁琐等问题,首先,详细阐明了三维服装软件CLO 3D和Marvelous Designer的虚拟服装迁移原理;其次,结合CLO 3D的虚拟服装迁移和自动转换虚拟模特功能,提出了一套针对三维扫描人体的个性化服装定制方案;最后,采用三维扫描人体开展虚拟服装迁移实验,验证了该方案在实际个性化服装定制应用中的可行性。研究结果表明:针对不同体型的三维扫描人体,可快速生成个性化虚拟服装、个性化样板和展示个性化虚拟试衣效果;生成的虚拟服装能够满足不同体型的个性化需求。该方法可提高个性化虚拟服装开发效率,为个性化服装定制提供技术支持。

Applications of Digital Correlation Method to Structure Inspection

In structure inspections, applications of optical techniques are rare, but the advantages of a noncontact, full field technique using a simple apparatus are attractive. The main requirements for structure inspection are the full-field strain measurement with the required precision and on-site measurement ability. The digital correlation method （DCM）, a new optical deformation measurement tool, can satisfy all of the requirements for structure inspection. A smoothing algorithm which can greatly improve the strain measurement precision, and a 3-D DCM have been developed in this paper. For verifying this improvement, a comparison of strain measurements by computer-simulated speckle images has been carried out. Additionally, three structure inspection examples that cover typical materials and structure styles are presented： the interface shear stress distribution for reinforced concrete piles bedded on rock, the 3-D strain distribution of a composite vessel structure, and stresses in a hookup that connects two steel bridge structures. All the examples show that the new structural inspection tool is exemplary and illustrates the obvious advantages of this optical non-destructive technique.

Updating digital elevation models via change detection and fusion of human and remote sensor data in urban environments

OpenStreetMap(OSM)currently represents the most popular project of Volunteered Geographic Information(VGI):geodata are collected by common people and made available for public use.Airborne Laser Scanning(ALS)enables the acquisition of high-resolution digital elevation models that are used for many applications.This study combines the advantages of both ALS and OSM,offering a promising new approach that enhances data quality and allows change detection:the mainly up-to-date 2D data of OSM can be combined with the high-resolution–but rarely updated–elevation information provided by ALS.This case study investigates building objects of OSM and ALS data of the city of Bregenz,Austria.Data quality of OSM is discerned by the comparison of building footprints using different true positive definitions(e.g.overlapping area).High quality of OSM data is revealed,yet also limitations of each method with respect to heterogeneous regions and building outlines are identified.For the first time,an up-to-date Digital Surface Model(DSM)combining 2D OSM and ALS data is achieved.A multitude of applications such as flood simulations and solar potential assessments can directly benefit from this data combination,since their value and reliability strongly depend on an up-to-date DSM.

建筑机电工程模块化预制装配施工典型应用及其专项技术

对建筑机电工程模块化预制装配施工的典型应用及专项技术进行了研究。围绕机电设备与管线模块化分割设计、装配施工、工装设备等问题,重点分析了制冷机房、空调机房、管弄井、管廊等不同场景机电设备与管线模块的装配安装技术。结果表明,合理运用三维激光扫描复测技术、装配施工误差综合补偿技术及装配施工信息化管理平台,有助于提高工效,减少人工消耗,缩短现场施工工期。虽然尚缺乏统一的模块化分割设计和物料编码规则,针对不同场景和形式模块单元的运输及安装工装器具也有待进一步开发和完善,但建筑机电设备与管线模块化装配施工仍是建筑机电工程融合数字化技术,是实现工业化建造的发展趋势。

三维激光扫描技术在水电大比例尺地形测量中的应用研究

依托Riegl三维激光扫描系统,介绍其系统组成及工作原理,以实例研究说明该技术在水电地形测量中应用的可行性,论述数据获取、点云拼接及数字高程模型的生成。经过初步应用研究表明,该技术获取的大比例尺地形图精度可靠,且工作效率高,对岸坡陡峭、植被稀少的高山峡谷中布置的水电工程枢纽,其应用优势更为明显。

Extraction of Feature Points for Non-Uniform Rational B-Splines(NURBS)-Based Modeling of Human Legs

Methods of digital human modeling have been developed and utilized to reflect human shape features.However,most of published works focused on dynamic visualization or fashion design,instead of high-accuracy modeling,which was strongly demanded by medical or rehabilitation scenarios.Prior to a high-accuracy modeling of human legs based on non-uniform rational B-splines(NURBS),the method of extracting the required quasi-grid network of feature points for human legs is presented in this work.Given the 3 D scanned human body,the leg is firstly segmented and put in standardized position.Then re-sampling of the leg is conducted via a set of equidistant cross sections.Through analysis of leg circumferences and circumferential curvature,the characteristic sections of the leg as well as the characteristic points on the sections are then identified according to the human anatomy and shape features.The obtained collection can be arranged to form a grid of data points for knots calculation and high-accuracy shape reconstruction in future work.

BIM技术在首寰度假酒店项目中的应用研究

通过数字化BIM技术在首寰度假酒店的实施应用,在建筑工程管理的传统应用模式基础上,利用BIM技术、三维扫描、数字管理平台等系列软件对施工管理、技术深化、质量控制、进度预控、成本控制等方面进行完善和创新,实现建设项目降本增效的目标,并形成了相关可持续应用的技术成果和标准。