A Semantic-Sensitive Approach to Indoor and Outdoor 3D Data Organization

Building model data organization is often programmed to solve a specific problem,resulting in the inability to organize indoor and outdoor 3D scenes in an integrated manner.In this paper,existing building spatial data models are studied,and the characteristics of building information modeling standards(IFC),city geographic modeling language(CityGML),indoor modeling language(IndoorGML),and other models are compared and analyzed.CityGML and IndoorGML models face challenges in satisfying diverse application scenarios and requirements due to limitations in their expression capabilities.It is proposed to combine the semantic information of the model objects to effectively partition and organize the indoor and outdoor spatial 3D model data and to construct the indoor and outdoor data organization mechanism of“chunk-layer-subobject-entrances-area-detail object.”This method is verified by proposing a 3D data organization method for indoor and outdoor space and constructing a 3D visualization system based on it.

3D Modelling from New and Existing Gravity Data of an Intrusive Body in the Northern Part of Kribi-Campo Sub-Basin in Cameroon

A new gravity survey was carried out in the northern part of the onshore Kribi- Campo sub-basin in Cameroon. The data were incorporated to the existing ones and then analyzed and modeled in order to elucidate the subsurface structure of the area. The area is characterized in its north-western part by considerably high positive anomalies indicative of the presence of a dense intrusive body. We find, 1) from the analysis of the gravity residual anomaly map, the high positive anomalies observed are the signature of a shallow dense structure;2) from the multi-scale analysis of the maxima of the horizontal gradient, the structure is confined between depths of 0.5 km and 5 km;3) from the quantitative interpretation of residual anomalies by spectral analysis, the depth to the upper surface of the intrusive body is not uniform, the average depth of the bottom is h1 = 3.6 km and the depths to particular sections of the roof of the intrusion are h2 = 1.6 km and h3 = 0.5 km;4) and the 3D modeling gives results that are suggestive of the presence of contacts between rocks of different densities at different depths and a dense intrusive igneous body in the upper crust of the Kribi zone. From the 3D model the dense intrusive igneous block is surrounded by sedimentary formations to the south-west and metamorphic formations to the north-east. Both formations have a density of about 2.74 g/cm3. The near surface portions of this igneous block lie at a depth range of 0.5 km to 1.5 km while its lower surface has a depth range of 3.6 km to 5.2 km. The shape of the edges and the bottom of the intrusive body are suggestive of the fact that it forms part of a broader structure underlying the Kribi-Campo sub-basin with a great influence on the sedimentary cover.

基于深度学习与点云数据的3D检测系统应用研究

为了解决高低差场景中平坦度高的2D视觉检测乏力的问题,基于深度学习和点云数据处理平台,融合3D点云格式图像和深度学习技术,建立微米精度、在线检测、成本可控的3D检测架构机制。采用相移和光栅投影结构光技术的硬件方案获取3D点云原始数据,基于强大的CPU和GPU处理芯片,对经过被测物体调制的光栅图案进行重新编码,并结合标定参数解算3D点云数据。对2D深度学习模型进行升级开发,可对点云数据进行标注、学习训练和检测,并将3D硬件、3D软件和3D算法进行整合。实验结果表明,所提系统有利于3D缺陷检测系统的落地,为智能3D检测设备奠定算法和软件基础。

3D Geological Modeling with Multi-source Data Integration in Polymetallic Region:A Case Study of Luanchuan,Henan Province,China

The development of 3D geological models involves the integration of large amounts of geological data,as well as additional accessible proprietary lithological, structural,geochemical,geophysical,and borehole data.Luanchuan,the case study area,southwestern Henan Province,is an important molybdenum-tungsten -lead-zinc polymetallic belt in China.

Alternative 3D Modeling Approaches Based on Complex Multi-Source Geological Data Interpretation

Due to the complex nature of multi-source geological data, it is difficult to rebuild every geological structure through a single 3D modeling method. The multi-source data interpretation method put forward in this analysis is based on a database-driven pattern and focuses on the discrete and irregular features of geological data. The geological data from a variety of sources covering a range of accuracy, resolution, quantity and quality are classified and integrated according to their reliability and consistency for 3D modeling. The new interpolation-approximation fitting construction algorithm of geological surfaces with the non-uniform rational B-spline(NURBS) technique is then presented. The NURBS technique can retain the balance among the requirements for accuracy, surface continuity and data storage of geological structures. Finally, four alternative 3D modeling approaches are demonstrated with reference to some examples, which are selected according to the data quantity and accuracy specification. The proposed approaches offer flexible modeling patterns for different practical engineering demands.

逆向建模与3D打印技术的应用案例分析

阐述采用光学扫描仪对破损零件的数据采集,Geomagic design X软件进行逆向建模。将三维模型导出为Stl格式文件,在Cura软件中进行切片处理,用Shining 3D打印机实施3D打印,完成耳机的装配。实践证明,此逆向建模及3D打印方法有效。

基于3D辅助器的结构楼板钢筋安装施工技术

以某工程为例,对基于3D辅助器的结构楼板钢筋安装施工技术进行研究,综述了采用三维设计软件建立钢筋安装辅助器模型图,运用3D打印技术打印出实体,施工时将各类板筋压入钢筋安装辅助器的对应卡口中,保证了保护层厚度,提高了钢筋定位安装精度和速度等一系列创新技术,确保了结构楼板钢筋安装分层清晰、定位准确、保护层厚度一致。

Component-based Topological Data Model for Three-dimensional Geology Modeling

On the study of the basic characteristics of geological objects and the special requirement for computing 3D geological model, this paper gives an object-oriented 3D topologic data model. In this model, the geological objects are divided into four object classes: point, line, area and volume. The volume class is further divided into four subclasses: the composite volume, the complex volume, the simple volume and the component. Twelve kinds of topological relations and the related data structures are designed for the geological objects.

Construction and visualization of 3D vacant place model

The method of building 3D model was discussed at first. Aiming at the feature of mine vacant place,a method to build the 3D vacant place model based on multi TIN (triangular irregular network) was put forward, and the data structure and visualization of vacant place were discussed. Then some crucial technologies of realizing function in 3D-GIS were proposed. In addition,the software about special 3D mapping and assaying was introduced.

THREE DIMENSIONAL DATA STRUCTURE AND DATA MODEL

D GISs were developed simultaneously in the late 1980s in a number of different disciplines.The development of these 3D GISs can not yet meet all needs for new representations and analytical tools in 3D environments.In this paper,the data structures,especially solid_based data representations are introduced.Then,a typical object_oriented data model is put forth to show a new data model.And at last,two data access methods are proposed to make the data model clear.

BUILDING MODELING FOR 3D CITY MODEL

New development in urban planning, cityscape, real estate management and the like, calls for new demands for 3D city model. There are so many objects in 3D city model such as building, river, road, and so on. The building model is very important in 3D city model. In recent years,a lot of research work about visualization has been done. In our opinions,visualization is only a part of 313 city model, while interactive operation about buildings is rather important as well. In order to implement interactive operation (create , edit, query,etc. ), good data structure and model must be developed.

An Approach to Computer Modeling of Geological Faults in 3D and an Application

3D geological modeling, one of the most important applications in geosciences of 3D GIS, forms the basis and is a prerequisite for visualized representation and analysis of 3D geological data. Computer modeling of geological faults in 3D is currently a topical research area. Structural modeling techniques of complex geological entities contain- ing reverse faults are discussed and a series of approaches are proposed. The geological concepts involved in computer modeling and visualization of geological fault in 3D are explained, the type of data of geological faults based on geo- logical exploration is analyzed, and a normative database format for geological faults is designed. Two kinds of model- ing approaches for faults are compared: a modeling technique of faults based on stratum recovery and a modeling tech- nique of faults based on interpolation in subareas. A novel approach, called the Unified Modeling Technique for stratum and fault, is presented to solve the puzzling problems of reverse faults, syn-sedimentary faults and faults terminated within geological models. A case study of a fault model of bed rock in the Beijing Olympic Green District is presented in order to show the practical result of this method. The principle and the process of computer modeling of geological faults in 3D are discussed and a series of applied technical proposals established. It strengthens our profound compre- hension of geological phenomena and the modeling approach, and establishes the basic techniques of 3D geological modeling for practical applications in the field of geosciences.

A Strategy for Loading Oblique Photogrammetry Models and Multilayer Basemap Data

With the development of drone technology and oblique photogrammetry technology, the acquisition of oblique photogrammetry models and basemap becomes more and more convenient and quickly. The increase in the number of basemap leads to excessively redundant basemap tiles requests in 3D GIS when loading oblique photogrammetry models, which slows down the system. Aiming at improving the speed of running system, this paper proposes a dynamic strategy for loading basemap tiles. Different from existing 3D GIS which loading oblique photogrammetry models and basemap tiles inde-pendently, this strategy dynamically loads basemap tiles depending on different height of view and the range of loaded oblique photogrammetry models. We achieve dynamic loading of basemap tiles by predetermining whether the basemap tiles will be covered by the oblique photogrammetry models. The experimental results show that this strategy can greatly reduce the num-ber of redundant requests from the client to the server while ensuring the user’s visual requirements for the oblique photogrammetric model.

Study on 3D Geological Model of Highway Tunnels Modeling Method

Geology is the base for highways and tunnels construction. With the fast development of national highway construction, highway tunnel construction project are more and more complex. The completeness and accuracy are essential for the planning, design and construction of projects, while the ground information is quite poor in systematic, reliable and timely aspects. Therefore, the development of underground road tunnels, and the implementation of informationized spatial information management is urgent for highway construction. 3D geological tunnel model is intuitive, high efficient and convenience which greatly facilitates the maintenance and security of highway tunnels construction and it will be the trend for the future highway tunnel development.

虚拟分割下复杂建筑立面纹理3D建模方法

针对因复杂建筑立面纹理特征难以捕捉,且存在噪声干扰,导致建模效果不佳的问题,提出一种基于虚拟分割的复杂建筑立面纹理3D建模方法。采集建筑立面像素信息数据,设置水平和垂直方向的特征标准参考量,采用虚拟分割法对不同立面区域的纹理实行分割,得到纹理变动向量。将特征信息看作是点云数据,设定去噪函数,计算不同特征的加权量完成去噪。以特征作为建模函数的初始输入,采取纹理映射方式,将复杂像素信息转换成简单信息,提高3D建模刻画的真实度,设计旋转平移矩阵,划分建筑立面的不同区域,根据区域内节点刻画3D建模函数,完成有效建模。仿真结果表明,所提方法建模质量表现较佳,建模结果与实际结果高度一致,且去噪效果较好。

An approach for converting orthographic projection drawings into 3D-CAD models

Abstract： Hand drawings and two dimensional （2D） CAD drawings have been replaced by three dimensional （3D） CAD models in mechanical design, but some 2D drawings produced before are needed in the new design. However, the techniques and software packages for automatically converting 2D drawings into 3D-CAD models with high precision have not yet been developed due to the difficulties to verify the validity of the drawings, to decide the hidden lines and eoncavo-convex faces, and to represent free-form surfaces. In addition, it is very time consuming to manually convert a large number of 2D drawings into 3D CAD models. To address these problems, we propose an approach for converting 2D drawings into 3D-CAD models automatically.

3D打印中数据精简处理技术

目前流行的3D打印方法是把模型数据切割成切片数据进行打印,但是切割后的轮廓上存在很多冗余数据点。针对该问题,文中提出一种在角度弦高法的基础上融合二分法和筛选法的简化处理算法。该方法将轮廓上的数据分割成一个一个的簇数据集,再根据簇内每个点的偏角度和弦高依次进行判断筛选;然后通过二分迭代的方法对簇数据进行重新聚类,以此来确定需要去除哪些数据点。选取1001个原始数据点的梅花形状轮廓为实验对象,当设定偏角阈值Δα=10°,弦高度阈值为Δh=0.1 mm时,所提算法精简率为80.82%,且用时仅为0.0049 s,重构曲线的平均误差仅为0.0237 mm。所提算法精简的效果比较理想,不仅能够在轮廓的曲率变化较高的地方保留足够的数据点,而且在轮廓的曲率变化较低处也能把细节的特征点很好地保留下来,保留的数据能够跟随曲率特征实现合理的分布。实测结果表明,要使精简的效果良好且快速稳定,需要把每次处理的数据簇的个数设定在10~20。

多源数据融合的高层建筑物三维建模研究

随着无人机的大规模普及,倾斜摄影测量技术应用越来越广泛,但是由于其技术特点,在数据采集过程中受角度、遮蔽等因素的影响,导致三维模型极易出现拉花、扭曲等问题。基于此,探讨了融合机载激光雷达(Light Laser Detection and Ranging,LiDAR)、地面数据采集和倾斜摄影技术的方法,以提高高层建筑物三维建模的精度和细节。机载LiDAR技术通过激光雷达扫描获取点云数据,提供建筑物的几何形状和细节信息,倾斜摄影技术可以提供建筑物纹理信息,与机载LiDAR技术结合可以提高建模的真实感和精度。点面三维激光扫描仪能够有效补充前两项技术的缺失,如补充细节数据。研究融合三种数据源的信息,综合利用它们的优势,为城市规划、建设和管理提供更准确、可靠的数据支持。

大规模城市场景数据在Unity 3D中加载及渲染技术的应用

随着电力三维应用功能的不断深化,大规模场景数据的动态加载成为电力三维应用中需要解决的问题。主要讨论了大规模城市场景数据在三维场景中的加载及渲染技术,根据城市建筑数据的特点,主要研究两部分内容:城市建筑数据的处理;海量城市模型渲染技术的实现。该系统构建了基于Unity 3D的三维渲染引擎,实现了大规模城市场景的高效渲染模块的开发。该系统作为电力三维系统的一部分,能够实现变电站、架空线、地下电缆等周边城市建筑模型的快速生成及高效展示,有助于深化其在架空线路、电缆通道等业务的应用。

面向水库型小流域的多源水利三维建模方法研究

针对大型河道三维可视化建模中采用激光雷达、声呐等传感器获取水下地形建模方式操作复杂且成本较高的缺陷,在利用基础测绘成果构建实景地形模型的基础上,采用多源三维模型融合方法对月塘水库小流域进行实景建模。首先采用倾斜摄影三维建模技术对重点水利工程进行实景建模,并利用专业建模软件对重要控制单元进行构件级建模;然后利用已有河道断面数据结合河流面状矢量数据,实现流域内胥浦河河道实景三维建模;最后通过人机交互方式对多源实景模型进行微调与相互印证,实现月塘水库小流域多源三维模型精准融合构建。研究成果可为河道型水库的预报调度与洪水风险分析提供可视化模型基础与决策支撑。