摘要

飞行器航路前方的“威胁态势图”

面向飞行器导航需求,针对传统空地环境警告信息繁杂导致情境意识薄弱和决策时间长等瓶颈问题,建立了机场环境威胁态势信息在语义空间的统一表示模型,提出了对多源、多尺度、多种分布类型的机场空地环境信息在语义空间的统一建模与动态更新方法,实现了从实时接入的动态观测数据中深度搜索威胁态势信息,并达到信息快速组织与检索的目的。从林芝机场的数据建模和实验结果表明,该方法能精准、高效的建立面向飞行器导航应用的动态机场环境威胁态势图。

摘要

针对公共安全应急响应中支持推理、挖掘和关联分析的地理视频建模难题,提出了一种显式表达视频变化的多层次地理视频语义模型,并用UML图进行描述.该模型的特点是：改变了传统视频流整体语义描述方法,通过面向变化的三域（特征域-行为过程域-事件域）定义地理视频语义的层次结构和数据的层次表达;在各层次语义描述中将地理环境语义与视频内容语义有机结合,支持多地理视频数据的关联表示.以公共安全事件监控视频为例阐明了模型的实用性和有效性.

摘要

为兼顾时空索引方法的空间利用率、时间效率和查询种类,提出了一种新的轨迹数据索引方法-HBSTR树.其基本思想是：轨迹采样点以轨迹节点的形式成组集中管理,哈希表用于维护移动目标的最新轨迹节点,轨迹节点满后作为叶节点插入时空R                                                    树,另外采用B                                                    树对轨迹节点构建一维索引,既有利于提升索引创建效率,又同时满足时空条件搜索和特定目标轨迹搜索等多种查询类型.为提升时空查询效率,提出了新的时空R                                                    树评价指标和节点选择子算法改进时空R 树插入算法,同时提出了一种时空R树的数据库存储方案.试验结果表明,HBSTR                                                    树在创建效率、查询效率和支持查询类型等方面综合性能优于现有方法,支持大规模实时轨迹数据库的动态更新和高效访问.

摘要

建筑信息模型(BIM)与地理信息系统(GIS)集成，不仅使得精细化的三维模型得到极大重用，同时两者的数据集成和共享可实现从几何到物理和功能特性的多尺度综合表达，已经成为新一代数字城市三维建模的关键途径之一。本文选取典型的BIM模型数据格式(RVT)，提出语义约束的RVT模型到CityGML模型的转换方法，以BIM模型丰富的语义信息为约束实现几何简化及转换，同时实现了几何部件与语义信息的一一映射及语义输出，并以建筑模型、暖通、桥梁模型为例进行了验证。

摘要

With the goal to achieve an accuracy navigation within the building                                                    environment, it is critical to explore a feasible way for building                                                    the connectivity relationships among 3D geographical features called                                                    in-building topology network. Traditional topology construction                                                    approaches for indoor space always based on 2D maps or pure geometry                                                    model, which remained information insufficient problem. Especially,                                                    an intelligent navigation for different applications depends mainly                                                    on the precise geometry and semantics of the navigation network. The                                                    trouble caused by existed topology construction approaches can be                                                    smoothed by employing IFC building model which contains detailed                                                    semantic and geometric information. In this paper, we present a                                                    method which combined a straight media axis transformation algorithm                                                    (S-MAT) with IFC building model to reconstruct indoor geometric                                                    topology network. This derived topology aimed at facilitating the                                                    decision making for different in-building navigation. In this work,                                                    we describe a multi-step deviation process including semantic                                                    cleaning, walkable features extraction, Multi-Storey 2D Mapping and                                                    S-MAT implementation to automatically generate topography                                                    information from existing indoor building model data given in IFC.

摘要

Indoor navigation is increasingly widespread in complex indoor                                                    environments, and indoor path planning is the most important part of                                                    indoor navigation. Path planning generally refers to finding the                                                    most suitable path connecting two locations, while avoiding                                                    collision with obstacles. However, it is a fundamental problem,                                                    especially for 3D complex building model. A common way to solve the                                                    issue in some applications has been approached in a number of                                                    relevant literature, which primarily operates on 2D drawings or                                                    building layouts, possibly with few attached attributes for                                                    obstacles. Although several digital building models in the format of                                                    3D CAD have been used for path planning, they usually contain only                                                    geometric information while losing abundant semantic information of                                                    building components (e.g. types and attributes of building                                                    components and their simple relationships). Therefore, it becomes                                                    important to develop a reliable method that can enhance application                                                    of path planning by combining both geometric and semantic                                                    information of building components. This paper introduces a method                                                    that support 3D indoor path planning with semantic information.

摘要

With the rapid development of sensor networks and Earth observation                                                    technology, a large quantity of disaster-related data is available,                                                    such as remotely sensed data, historic data, case data, simulated                                                    data, and disaster products. However, the efficiency of current data                                                    management and service systems has become increasingly difficult due                                                    to the task variety and heterogeneous data. For emergency                                                    task-oriented applications, the data searches primarily rely on                                                    artificial experience based on simple metadata indices, the high                                                    time consumption and low accuracy of which cannot satisfy the speed                                                    and veracity requirements for disaster products. In this paper, a                                                    task-oriented correlation method is proposed for efficient disaster                                                    data management and intelligent service with the objectives of 1)                                                    putting forward disaster task ontology and data ontology to unify                                                    the different semantics of multi-source information, 2) identifying                                                    the semantic mapping from emergency tasks to multiple data sources                                                    on the basis of uniform description in 1), and 3) linking                                                    task-related data automatically and calculating the correlation                                                    between each data set and a certain task. The method goes beyond                                                    traditional static management of disaster data and establishes a                                                    basis for intelligent retrieval and active dissemination of disaster                                                    information. The case study presented in this paper illustrates the                                                    use of the method on an example flood emergency relief task.

摘要

Public security incidents have been increasingly challenging to                                                    address with their new features, including large-scale mobility,                                                    multi-stage dynamic evolution, spatio-temporal concurrency and                                                    uncertainty in the complex urban environment, which require                                                    spatio-temporal association analysis among multiple regional video                                                    data for global cognition. However, the existing video data                                                    organizational methods that view video as a property of the spatial                                                    object or position in space dissever the spatio-temporal                                                    relationship of scattered video shots captured from multiple video                                                    channels, limit the query functions on interactive retrieval between                                                    a camera and its video clips and hinder the comprehensive management                                                    of event-related scattered video shots. GeoVideo, which maps video                                                    frames onto a geographic space, is a new approach to represent the                                                    geographic world, promote security monitoring in a spatial                                                    perspective and provide a highly feasible solution to this problem.                                                    This paper analyzes the large-scale personnel mobility in public                                                    safety events and proposes a multi-level, event-related organization                                                    method with massive GeoVideo data by spatio-temporal trajectory.                                                    This paper designs a unified object identify(ID) structure to                                                    implicitly store the spatio-temporal relationship of scattered video                                                    clips and support the distributed storage management of massive                                                    cases. Finally, the validity and feasibility of this method are                                                    demonstrated through suspect tracking experiments.

摘要

Dynamic flood disaster simulation is an emerging and promising                                                    technology significantly useful in urban planning, risk assessment,                                                    and integrated decision support systems. It is still an important                                                    issue to integrate the large assets such as dynamic observational                                                    data, numerical flood simulation models, geographic information                                                    technologies, and computing resources into a unified framework. For                                                    the intended end user, it is also a holistic solution to create                                                    computer interpretable representations and gain insightful                                                    understanding of the dynamic disaster processes, the complex                                                    impacts, and interactions of disaster factors. In particular, it is                                                    still difficult to access and join harmonized data, processing                                                    algorithms, and models that are provided by different environmental                                                    information infrastructures. In this paper, we demonstrate a virtual                                                    geographic environments-based integrated environmental simulation                                                    framework for flood disaster management based on the notion of                                                    interlinked resources, which is capable of automated accumulating                                                    and manipulating of sensor data, creating dynamic geo-analysis and                                                    three-dimensional visualizations of ongoing geo-process, and                                                    updating the contents of simulation models representing the real                                                    environment. The prototype system is evaluated by applying it as a                                                    proof of concept to integrate in situ weather observations,                                                    numerical weather and flood disaster simulation models,                                                    visualization, and analysis of the real time flood event. Case                                                    applications indicate that the developed framework can be adopted                                                    for use by decision-makers for short-term planning and control since                                                    the resulting simulation and visualization are completely based on                                                    the latest status of environment.

Abstract

Abstract

三维GIS 是当今乃至未来GIS 技术的主要标志性内容之一，它突破了空间信息在二维地图平面中单调表现                                                    的束缚，为各行各业以及人们的日常生活提供了更有效的辅助决策支持。本文重点介绍了三维GIS 的数据模型、                                                    数据库管理和可视化分析等关键技术及其研究进展，并以武汉市为例展示了三维GIS 对城市立体空间的整体表                                                    达，为大城市、全市域的三维数字城市建设奠定了基础，最后探讨了在智慧城市建设与城市安全中三维GIS将发挥                                                    日益重要的时空信息承载引擎与空间智能技术支撑作用。

Abstract

以“4·20”芦山7.0级强烈地震中应急测绘保障为例,系统分析了目前应急测绘保障工作的机制,以及数据获取、传输、处理、发布以及应急测绘数据共享多个环节中存在的突出问题,提出了一种新的应急测绘保障体系架构和任务驱动的聚焦服务机制。

Abstract

基于三维建筑空间表达充分结合建筑防火专题语义信息建立了面向建筑物内部空间划分与通达性分析的一体化语义描述并结合防火部件层次的动态特征发展面向室内火灾动态疏散过程的三维建筑信息模型从而辅助火灾应急疏散的三维空间逃生分析                                                    基于实验构建的三维建筑信息模型及其基于语义的动态联通网络证明了其在室内火灾动态疏散中的特殊价值

Abstract

为实现大规模地形景观和精细工程设施模型在三维GIS中的无缝集成管理,并支持工程设施全生命周期的共享应用,提出了一种可根据设计参数自动建立复杂设施三维模型并交互式编辑修改的方法,扩展了三维GIS数据模型,实现了三维几何模型与其参数信息的有机集成与同步更新,并以桥梁模型的构建为例验证了该方法的可行性和有效性。

Abstract

近年来,建筑信息模型(BIM)与地理信息系统(GIS)的集成应用越来越广泛且深入,不同专业领域通过简单模型转换实现信息交互的方法由于只保留了少量的语义信息从而导致了应用的分散和独立,局限性十分明显.IFC和CityGML分别为BIM和GIS领域内通用的数据模型标准,两者之间的几何和语义信息共享将为BIM和GIS的集成奠定基础.本文基于IFC和CityGML标准,提出IFC几何要素过滤方法以及IFC到CityGML的语义映射规则,为IFC与CityGML建筑模型的几何、语义信息互操作提供一种通用手段,并通过实例进行了验证.

Abstract

商业中心、交通枢纽、医院、停车场等复杂室内及地下空间的安全管理与应急响应对室内外无缝导航与位置服务的需求日益迫切,提出了一种室内位置信息模型,扩展了OGC标准CityGML和IndoorGML中的位置信息描述,提供了描述室内相对位置和室内绝对位置的本体,介绍了一种针对三维建筑物模型的室内空间自动提取方法,为智能位置服务奠定了重要基础。

Abstract

传统基于“图层付象”的组织方法，没有考虑三维城市模型的不同内容以及不同细节层次的粒度差                                                    异，导致在网络环境下的传输效率低，难以满足多用户并发访问的流畅可视化。深入分析了大范围漫游与小                                                    范围聚焦的用户体验特点，通过元数据统筹管理和对象离散化，即时响应用户请求，减少无效数据传输，保证                                                    了多用户并发环境下的高效调度和浏览。针对模型LoI)和分解的对象，设计了结构统一的对象ID,隐式存储                                                    关联关系并支持分布式模型存储管理。以分布式数据库MongoDB为平台进行实验，验证了本文方法的可行 性和有效性。

The task-oriented FSM of the IDISS

Abstract

The Chinese Government and citizens face enormous challenges of                                                    disaster management as widespread devastation, economic damages, and                                                    loss of human lives caused by increasing natural disasters. Disaster                                                    management requires a complicated iterative process that includes                                                    disaster monitoring, early detection, forecasting, loss assessment,                                                    and efficient analysis of disaster reduction. Each task typically                                                    involves the use of technologists and multiple geospatial                                                    information resources, including sensors, data sources, models,                                                    geo-tools, software packages, and computing resources. However, most                                                    existing disaster management systems operate in a typical passive                                                    data-centric mode, where resources cannot be fully utilized. This                                                    impediment is partially being addressed by the increasingly complex                                                    application requirements and the growing availability of diverse                                                    resources. In this paper, we summarize and analyze the practical                                                    problems experienced by the National Disaster Reduction Application                                                    System of China. To address the issues of data-centric, centralized,                                                    isolated solutions, we propose a novel Focusing Service Mechanism,                                                    which is capable of scheduling and allocating for optimum                                                    utilization of multiple resources, to dynamically generate                                                    collaborative and on-demand disaster information services. We also                                                    demonstrate the design and implementation of the Integrated Disaster                                                    Information Service System (IDISS). Through the service strategies                                                    of Virtualizing, Wrapping, and Integrating, disaster-related                                                    resources are constructed into services in the IDISS. These services                                                    are dynamically aggregated into focusing service chains, for diverse                                                    disaster management tasks. Actual applications illustrate that the                                                    proposed service system can significantly improve the capability of                                                    disaster management in China.

Structure of a complete VGE

Abstract

Abstract Virtual Geographic Environments (VGEs) are proposed as a new                                                    generation of geographic analysis tool to contribute to human                                                    understanding of the geographic world and assist in solving                                                    geographic problems at a deeper level. The development of VGEs is                                                    focused on meeting the three scientific requirements of Geographic                                                    Information Science (GIScience) — multi-dimensional visualization,                                                    dynamic phenomenon simulation, and public participation. To provide                                                    a clearer image that improves user understanding of VGEs and to                                                    contribute to future scientific development, this article reviews                                                    several aspects of VGEs. First, the evolutionary process from maps                                                    to previous GISystems and then to VGEs is illustrated, with a                                                    particular focus on the reasons VGEs were created. Then, extended                                                    from the conceptual framework and the components of a complete VGE,                                                    three use cases are identified that together encompass the current                                                    state of VGEs at different application levels: 1) a tool for                                                    geo-object-based multi-dimensional spatial analysis and                                                    multi-channel interaction, 2) a platform for geo-process-based                                                    simulation of dynamic geographic phenomena, and 3) a workspace for                                                    multi-participant-based collaborative geographic experiments. Based                                                    on the above analysis, the differences between VGEs and other                                                    similar platforms are discussed to draw their clear boundaries.                                                    Finally, a short summary of the limitations of current VGEs is                                                    given, and future directions are proposed to facilitate ongoing                                                    progress toward forming a comprehensive version of VGEs.

Abstract

The difference between real-time CSCW systems and traditional                                                    distributed systems is that the former one is supposed to provide a                                                    natural, free and fast interface for multi-user interaction.                                                    However, the typical multi-user interaction method applied in 3D CAD                                                    systems is strict consistency maintenance, such as locking mechanism                                                    and floor control, which may generate a stagnant and unnatural                                                    interface. This paper proposes a 3D semanticbased Operational                                                    transformation (OT) to support less constrained multi-user                                                    interaction and to achieve consistency in collaborative CAD editing                                                    (co-CAD) systems, and it can be used in many collaborative CAD/CAM                                                    industries.

Abstract

A complex 3D city model contains detailed descriptions of both its                                                    appearance and its internal structure, including architectural                                                    components. Because of the topological complexity and the large                                                    volumes of data in such models, profiling is an effective method to                                                    present the internal structure, the distributed characteristics, and                                                    the hierarchical relationships of the model to provide intuitive                                                    visual information to the viewer and to reveal the relationships                                                    between the elements of the model and the whole. However, with                                                    commonly used boundary descriptions, it is difficult to                                                    comprehensively preserve the consistency of three-dimensional                                                    profiling using existing algorithms based on geometric constraints.                                                    This paper proposes a novel semantics-constrained profiling approach                                                    to ensure the consistency of the geometrical, topological, and                                                    semantic relationships when profiling complex 3D city models. The                                                    approach transforms the 3D model’s boundary description, defined                                                    using the CityGML standard of the Open Geospatial Consortium (OGC),                                                    into a set of unified volumetric features described as solids. This                                                    approach is characterized by (1) the use of the concepts of semantic                                                    relationships, virtual edges, and virtual surfaces; (2) the semantic                                                    analysis of 3D models and the extraction of volumetric features as                                                    basic geometric analytic units; (3) the completion of structural                                                    connectivity and space coverage for each volumetric feature, which                                                    is represented as a solid model; and (4) the use of a reliable 3D                                                    Boolean operation for efficient and accurate profiling. A typical                                                    detailed 3D museum model is used as an example to illustrate the                                                    profiling principle, and the experimental results demonstrate the                                                    correctness and effectiveness of this approach.

Abstract

Highly detailed surface models and their real-time applications are                                                    increasingly popular in architecture, construction and other design                                                    and engineering fields. However, new and related problems have                                                    emerged concerning the efficient management of the resulting large                                                    datasets and the seamless integration of heterogeneous data.                                                    Moreover, the increasingly common requirements of local                                                    high-fidelity modeling combined with large-scale landscapes lead to                                                    difficulty in the seamless multi-resolution representation of hybrid                                                    triangulated irregular networks (TINs) and Grids. This paper                                                    presents a hybrid data structure with high-efficiency and a related                                                    organizational method for the seamless integration of                                                    multi-resolution models. This approach is characterized by (1) a                                                    self-adaptive algorithm for feature-preserving surface partitioning,                                                    (2) an efficient hybrid index structure for combined Grid and TIN                                                    surfaces, and (3) a view-dependent scheduling strategy with access                                                    to Grids of necessary resolution, giving priority to the dynamic                                                    loading of TINs. Experiments using typical real design datasets of                                                    highway constructions are able to achieve accuracy-preserved and                                                    real-time availability of results that prove the validity and                                                    efficiency of this approach.

Abstract

GIS is now faced with the challenge how to represent and understand                                                    the fast-paced, constantly changing world, given increasingly                                                    real-time data including readings from large-scale distributed                                                    sensors and large quantities of simulation data generated by                                                    computation models. Traditional static GIS pays more attention to                                                    representing historic data and Temporal GIS(TGIS) only treats time                                                    as a occasional but not critical factor and can't support the                                                    explicit change representation. In this context, Real-time GIS(RGIS)                                                    is put forward and its data model becomes a key problem how to make                                                    an appropriate abstraction over the rapid changes implied in                                                    real-time data stream and establish the general interaction                                                    relationship between them. The paper proposes a spatiotemporal                                                    changeoriented three-domain model with the emphasis on the semantic                                                    interaction relationship of object, event and process. Based on this                                                    model, a semantic enrichment method for multi-scale spatiotemporal                                                    change is put forward. Finally, as a RGIS application, indoor fire                                                    disaster simulation is illustrated and proves the validity of the                                                    proposed model.

Abstract

Aiming at the increasing requirements of seamless indoor and outdoor                                                    navigation and location service, a Chinese standard of                                                    Multidimensional Indoor Location Information Model is being                                                    developed, which defines ontology of indoor location. The model is                                                    complementary to 3D concepts like CityGML and IndoorGML. The goal of                                                    the model is to provide an exchange GML-based format for location                                                    needed for indoor routing and navigation. An elaborated user                                                    requirements analysis and investigation of state-of-the-art                                                    technology in expressing indoor location at home and abroad was                                                    completed to identify the manner humans specify location. The                                                    ultimate goal is to provide an ontology that will allow absolute and                                                    relative specification of location such as "in room 321", "on the                                                    second floor", as well as, "two meters from the second window", "12                                                    steps from the door"

Abstract

Research in support of indoor mapping and modelling (IMM) has been                                                    active for over thirty years. This research has come in the form of                                                    As-Built surveys, Data structuring, Visualisation techniques,                                                    Navigation models and so forth. Much of this research is founded on                                                    advancements in photogrammetry, computer vision and image analysis,                                                    computer graphics, robotics, laser scanning and many others.                                                    While IMM used to be the privy of engineers, planners, consultants,                                                    contractors, and designers, this is no longer the case as commercial                                                    enterprises and individuals are also beginning to apply indoor                                                    models in their business process and applications. There are three                                                    main reasons for this. Firstly, the last two decades have seen                                                    greater use of spatial information by enterprises and the public.                                                    Secondly, IMM has been complimented by advancements in mobile                                                    computing and internet communications, making it easier than ever to                                                    access and interact with spatial information. Thirdly, indoor                                                    modelling has been advanced geometrically and semantically, opening                                                    doors for developing user-oriented, context-aware applications. This                                                    reshaping of the public’s attitude and expectations with regards to                                                    spatial information has realised new applications and spurred demand                                                    for indoor models and the tools to use them.                                                    This paper examines the present state of IMM and considers the                                                    research areas that deserve attention in the future. In particular                                                    the paper considers problems in IMM that are relevant to commercial                                                    enterprises and the general public, groups this paper expects will                                                    emerge as the greatest users IMM.                                                    The subject of indoor modelling and mapping is discussed here in                                                    terms of Acquisitions and Sensors, Data Structures and Modelling,                                                    Visualisation, Applications, Legal Issues and Standards. Problems                                                    are discussed in terms of those that exist and those that are                                                    emerging. Existing problems are those that are currently being                                                    researched. Emerging problems are those problems or demands that are                                                    expected to arise because of social changes, technological                                                    advancements, or commercial interests.                                                    The motivation of this work is to define a set of research problems                                                    that are either being investigated or should be investigated. These                                                    will hopefully provide a framework for assessing progress and                                                    advances in indoor modelling. The framework will be developed in the                                                    form of a problem matrix, detailing existing and emerging problems,                                                    their solutions and present best practices. Once the framework is                                                    complete it will be published online so that the IMM community can                                                    discuss and modify it as necessary. When the framework has reached a                                                    steady state an empirical benchmark will be provided to test                                                    solutions to posed problems. A yearly evaluation of the problem                                                    matrix will follow, the results of which will be published.

Abstract

洪涝灾害损失评估是防洪减灾科学决策的基础，其中洪水淹没分析是准确提取洪水淹没范围、水深及历时等灾情信息的关键。洪水淹没分析主要采用数字高程模型数据（DEM），由于DEM的格网分辨率与高程精度有限，常出现异常的洼地或平地，导致难以可靠计算每个格网点处的流向，而传统方法采用统一高程的洼地填平处理又使得容易出现洪水演进过程中复杂起伏地形水面爬坡以及平坦地形水位断流的问题，为此本文提出了顾及流速和淹没时间的自适应逐点水位修正算法，即在DEM坡面流模拟的基础上，根据洪水水流特性、地形、边界变化、水流速度、水深变化以及淹没点的淹没时间，计算水位修正值，对洪水演进过程中每个格网点的水位进行修正，采用多种地貌类型的DEM数据进行实验，证明洪水演进的淹没范围、水深及历时的实时计算结果准确可靠，可为快速评估灾害损失与防洪决策服务提供更为科学的依据。

Abstract

Typical characteristics of remote sensing applications are concurrent                                                    tasks, such as those found in disaster rapid response. The existing                                                    composition approach to geographical information processing service                                                    chain, searches for an optimisation solution and is what can be                                                    deemed a “selfish” way. This way leads to problems of conflict                                                    amongst concurrent tasks and decreases the performance of all                                                    service chains. In this study, a non-cooperative game-based                                                    mathematical model to analyse the competitive relationships between                                                    tasks, is proposed. A best response function is used, to assure each                                                    task maintains utility optimisation by considering composition                                                    strategies of other tasks and quantifying conflicts between tasks.                                                    Based on this, an iterative algorithm that converges to Nash                                                    equilibrium is presented, the aim being to provide good convergence                                                    and maximise the utilisation of all tasks under concurrent task                                                    conditions. Theoretical analyses and experiments showed that the                                                    newly proposed method, when compared to existing service composition                                                    methods, has better practical utility in all tasks.

Abstract

The real-time visualization of 3D GIS at a whole city scale always                                                    faces the challenge of dynamic data loading with high-efficiency.                                                    Based on the multi-tier distributed 3D GIS framework, this paper                                                    presents a multi-level cache approach for dynamic data loading. It                                                    aims to establish in 3D GIS spatial database engine (3DGIS-SDE) the                                                    unified management mechanism of caches on three levels, including:                                                    the client memory cache (CMC) oriented to sharing application, the                                                    client file cache (CFC) organized by index, as well as the                                                    application server memory cache (ASMC) of structural consistency.                                                    With the help of the proposed optimized cache replacement policy,                                                    multi-level cache consistency maintenance as well as multithread                                                    loading model designed in the paper, the engine is able to                                                    adaptively make full use of each-level caches according to their own                                                    application properties and achieve effective coordination between                                                    them. Finally, a practical 3D GIS database based on Oracle 11g is                                                    employed for test. The experimental results prove this approach                                                    could satisfy multi-user concurrent applications of 3D visual                                                    exploration.

Abstract

针对飞行器可视导航中复杂空地环境时空要素统一精准表示的难题，本文提出了面向飞行器可视导航的复杂空地环境动态3维表示的GIS数据模型和相应的时刻数据存储结构，并用UML图进行了描述。该模型综合考虑了复杂空地环境要素多维、动态、边界模糊等特点，刻画了多维动态时空数据在空间、时间、尺度、语义四个方面的特征及其相互关系。最后，以某机场的空地环境数据的组织、分析和可视化为例，验证了该模型的实用性。

Abstract

面向大型土木工程设计,提出了一种运用WMS共享空间数据源并实现高效应用集成的工程设计应用技术体系。首先,直接针对WMS数据服务器定向开发数据获取应用,通过高效并行多线程实现空间数据的分块网络传输,同时结合本地缓存机制与网络共享,实现了一种双轨存储访问机制;其次,基于独立的应用下载与嵌入的实时线程分配,实现了远程数据的本地化模拟应用环境与分布式共享协同;再次,针对WMS数据的应用,实现了空间数据向工程数据的高精度转换与工程制图出图体系,开发了统一的全球三维可视化平台,用于直观地综合表达各种WMS数据源。

Abstract

车载激光扫描点云数据已经成为数字城市和危机管理等领域越来越重要的三维空间信息源,针对大规模点云数据高效管理的技术瓶颈,提出一种八叉树和三维R树集成的空间索引方法——3DOR树,充分利用八叉树的良好收敛性创建R树叶节点,避免逐点插入费时过程,同时R树平衡结构保证良好的数据检索效率。并还扩展R树结构生成多细节层次（LOD）点云模型,提出一种支持缓存的多细节层次点云数据组织方法。试验证明,该方法具有良好的空间利用率和空间查询效率,支持多细节层次描述能力和数据缓存机制,可应用于大规模点云数据的后处理与综合应用。

Abstract

Many 3D GIS applications require 3D building models with different                                                    LoD (Level of Detail) that satisfy certain quality criteria.                                                    However, because of their complexity, most detailed 3D building                                                    models available are still produced manually, which results in                                                    inevitable geometric and topological errors. These errors hinder the                                                    downstream processing of such models. And existing researches on LoD                                                    production either focus on the simplification of smooth polygonal                                                    mesh or the generalization of regular prismatic building models. The                                                    generalization of detailed 3D building models is still immature.                                                    Aiming at producing cleaned models of different LoD for existing                                                    hand-made 3D building models, this paper starts by investigating two                                                    typical modeling errors of such models, incompleteness and                                                    separation. Repair methods with reasonable assumptions of buildings                                                    are then proposed for each type of errors. The generalization method                                                    based on morphological operations is then employed, coupled with                                                    model repair, to generate error-free simplified models.

Abstract

Spatial data balancing distribution can evidently improve the                                                    performance of parallel spatial database in shared nothing parallel                                                    architecture. Considering spatial locality and unstructured variable                                                    length characteristics of spatial data, this paper proposes a                                                    dynamic spatial data balancing distribution method under shared                                                    nothing parallel database environment. By using Hilbert ordering                                                    code to keep spatial locality relationship between spatial objects,                                                    the presented method can fulfill spatial data static balancing                                                    distribution status, which depends on hierarchically decomposing                                                    Hilbert space-filling curve code to allocate approximately even                                                    spatial data volume to parallel nodes in distributed network. Then                                                    spatial proximity index is introduced to resolve spatial data                                                    unbalancing problem caused by spatial database dynamic updating.                                                    Through moving spatial data fragments to goal node which is the                                                    minimum spatial proximity with data moving out node, the spatial                                                    database redistributing strategy can attain dynamic data balance                                                    among all network parallel nodes. Our experimental results show that                                                    the proposed method can effectively improve parallel performance                                                    deterioration resulted from spatial data unbalancing and achieve                                                    spatial data dynamic balancing distribution in parallel spatial                                                    database.

Abstract

多细节层次表达是三维GIS的重要特征之一。为提高细节层次模型的管理效率，本文提出一种扩展多细节层次功能的三维R树索引方法，通过全局优化和三维聚类分析建立动态三维R树索引，研制了先自下而上、后自上而下全局搜索的节点选择算法和基于k-medoids聚类算法的节点分裂算法，保证节点尺寸均匀、形状规则以及重叠减少。基于良好的三维树形结构，本文扩展了传统的三维R树索引结构，实现R树索引和细节层次模型的无缝集成。为验证本文方法的有效性，通过仿真实验，结果证明了本文方法能很大程度地提升多细节层次三维城市模型数据库的空间查询效率，具有较好的应用前景和实用价值。

Abstract

三维模型多细节层次的自适应控制是三维GIS和虚拟环境等领域研究的难点问题之一，针对大规模三维城市建模需要，本文介绍了一种基于三维R树索引的多细节层次(以下简称LOD)管理方法，从叶节点层向根节点自动生成LOD模型，并设计实现了视锥体查询和LOD检索的算法。通过实验分析，证明本文的LOD定义参数能够定量调整场景复杂度，进而自适应控制三维模型可视化的细节层次，适合建筑物类型地物的LOD描述。

Abstract

针对大规模三维城市建模与数据库协同应用,设计实现了一种高效的三维GIS数据库引擎,支持基于Oracle                                                    11g的多模式数据库管理;提出了顾及语义的三维空间数据库模型,为地上下室内外三维空间数据的一体化组织管理奠定了基础。介绍了该引擎涉及的多层次三维空间索引、多级缓存、多线程调度以及异步通信传输等关键技术,并用武汉市三维城市模型数据进行了试验分析,验证了该引擎的有效性和可靠性。

Abstract

从基本概念、应用需求和技术动态等方面就3维GIS技术的发展与演进进行了简要评述，强调了专业化与大众化两种应用对3维GIS提出的不同挑战。

Abstract

Aiming at the integrative management and comprehensive applications                                                    of large-scale 3D geospatial information covering the full 3D space                                                    of a city, this paper briefly introduces the design and                                                    implementation of a full 3D GIS platform: GeoScope, which provides a                                                    professional solution for the massive full three-dimensional                                                    geospatial data integration, management, analysis, visualization,                                                    and applications. GeoScope is characterized by: (1) extendible                                                    software architecture based on the hierarchical message bus,                                                    facilitates multimodal integrative applications of 2D GIS and 3D                                                    GIS; (2) unified 3D city models, support multiscale semantic                                                    representation of outdoor & indoor and aboveground & underground 3D                                                    objects; (3) high-efficient 3D geospatial database engine, supports                                                    integrated management of massive 3D geospatial data for real-time                                                    applications; and (4) high-performance visualization engine                                                    exploiting the massively parallel computation architecture of modern                                                    GPUs, supports real-time realistic rendering of large-scale                                                    complicated 3D geospatial environments. The successful pilot                                                    application of GeoScope is also illustrated with the 3D city models                                                    of 8494 km2 of the whole Wuhan City, the largest city in middle                                                    China.

Abstract

Web services make tools which used to be merely accessible to the                                                    specialist available to all, and permitting previous manual data                                                    processing and analysis tasks to be automated. One of key problem is                                                    Web services composition in terms of Quality of Service (QoS). There                                                    are many task concurrencies, such as remote sensing image                                                    processing, in computation-intensive scientific applications.                                                    However, existing Web service optimal combination approaches are                                                    mainly focused on single tasks by using "selfish" behavior to pursue                                                    optimal solutions. This causes conflicts because many concurrent                                                    tasks are competing for limited optimal resources, and the reducing                                                    of service quality in services. Based on the best reply function of                                                    quantified task conflicts and game theory, this paper establishes a                                                    mathematical model to depict the competitive relationship between                                                    multitasks and Web service under QoS constraints and it guarantees                                                    that every task can obtain optimal utility services considering                                                    other task combination strategies. Moreover, an iterative algorithm                                                    to reach the Nash equilibrium is also proposed. Theory and                                                    experimental analysis show the approach has a fine convergence                                                    property, and can considerably enhance the actual utility of all                                                    tasks when compared with existing Web services combinatorial                                                    methods. The proposed approach provides a new path for QoS-aware Web                                                    service with optimal combinations for concurrent tasks.

Description of hierarchical levels of                                                        detail

Abstract

Aiming at the increasing critical issues of existing 2D plans and                                                    map‐based methodology for integrated management of advanced                                                    buildings and related dynamic property rights in complicated 3D                                                    built environments, a novel semantics‐based 3D dynamic house                                                    property model with hierarchical levels of detail is proposed in                                                    this paper, based on comprehensive analysis of 3D house property                                                    objects and various application requirements. This model is                                                    characterized by: (1) 3D geometric semantics: a 3D geometry                                                    hierarchy of exterior and interior of buildings is defined; (2)                                                    thematic semantics, comprehensive house property object and related                                                    property right relationships are illustrated; (3) temporal                                                    semantics, dynamic representation of house property driven by both                                                    geometric events and property right events is involved. This model                                                    facilitates comprehensive data mining to analyze spatial                                                    relationships and dynamic change of property rights in real 3D built                                                    environments and can also support the sale and lease of real estate,                                                    facility management, house planning and so on.

The comparison results of a facade (Eq                                                        represents equal interval and exp represents exponential                                                        interval)

Abstract

Aiming at the fundamental issue of optimal design of discrete levels                                                    of detail (LOD) for the visualization of complicated 3D building                                                    façades, this paper presents a new quantitative analytical method of                                                    perceptible 3D details based on perceptual metric. First, the                                                    perceptual metric is defined as the quantitative indicator of the                                                    visual perceptibility of façade details at a given viewing distance.                                                    Then, according to the human vision system, an algorithm employing                                                    2D discrete wavelet transform and contrast sensitivity function is                                                    developed to extract the value of perceptual metric from the                                                    rendered image of the façade. Finally, a perceptual metric function                                                    is defined, based on the perceptual metric values extracted at equal                                                    interval viewing distances. The minimum detail redundancy model is                                                    then proposed for the optimal design of discrete LODs. This method                                                    provides a quantitative instruction for generating discrete LODs.                                                    The experimental results prove the effectiveness and great potential                                                    of this method.

Abstract

In recent years, the necessity of the incorporation of semantic                                                    information into three-dimensional city models (3DCMs) has become a                                                    consensus in 3D GIS field. In order to provide practical support for                                                    visual applications concerned with semantics, this paper firstly                                                    presents an extended semantic model based on the CityGML standard,                                                    which was worked out for the general storage and representation of                                                    semantics. In this model, concepts like Room, Corridor and Stair are                                                    all derived from concept Space which corresponds to the concept of                                                    Room in CityGML. This extension will benefit the indoor structure                                                    representation. Geological feature is also supported by the model                                                    for the underground analysis. Next, for the promotion of semantic                                                    modeling by this model, a semi-automatic process of semantic                                                    enrichment is implemented in a data integration tool. It provides an                                                    adaptive way to link semantics with pure geometry. Finally, two                                                    typical cases of visual exploration are illustrated to prove the                                                    model's practicability in a national 3D GIS project of China. One is                                                    indoor routing, which adopts this model to extract the geometric                                                    path and thus enrich traditional semantic-enhanced navigation                                                    routine; another case is unified profiler, where semantics are                                                    intergrated in order to fill up the cross section correctly and                                                    ensure the topological and semantic consistency.

Abstract

To improve the reusability of three-dimensional (3D) models and                                                    simplify the complexity of natural scene reconstruction, this paper                                                    presents a 3D model database for universal 3D GIS. After the                                                    introduction of its extensible function architecture, accompanied by                                                    the conclusion of implicit spatial-temporal hierarchy of models in                                                    any reconstructed scene of 3D GIS for general purpose, several key                                                    issues are discussed in detail, such as the storage and management                                                    of 3D models and related retrieval and load method, as well as the                                                    interfaces for further on-demand development. Finally, the validity                                                    and feasibility of this model database are proved through its                                                    application in the development of 3D visualization system of railway                                                    operation.

Abstract

In this paper, a novel method, namely contextual routing and                                                    navigation, is proposed. This method is based on the author's                                                    proposed hierarchical, lane-oriented 3D road network. The key to                                                    implement contextual routing and navigation is to adopt                                                    cognition-based hierarchical routing strategy and the view-based                                                    multi-scale navigation strategy. The two strategies enable users                                                    routing on roadway centreline, carriageway or lane and provides 2D,                                                    2.5D and 3D communicating based on user defined context. A prototype                                                    is also developed in the VGEGIS system and the experimental results                                                    have confirmed the effectiveness and efficiency of the method. The                                                    paper will provide a contribution to flexible location-based                                                    services by innovatively considering the hierarchical knowledge of                                                    the road network system and contextual visualization needs.

Abstract

Aiming at the massive data organization and management of textures                                                    with various sizes for real-time rendering of large-scale 3D city                                                    models, this paper proposes a new method: a texture spatial index                                                    tree is built up based on the hierarchical spatial index of 3D                                                    geometries, and then the texture data is written into mapping files                                                    structure through depth-first and hierarchical iteration for the                                                    clustering of data blocks, which facilitates the flexible                                                    size-changed disk I/O operations. Experimental results prove such                                                    kind of storage is more compact and more effective than single file                                                    storage method, and enables the fast access of texture data.

Abstract

Especially for landmark buildings or in the context of cultural                                                    heritage documentation, highly detailed digital models are being                                                    created in many places. In some of these models, surfaces are                                                    represented by tiles which are individually modeled as solid shapes.                                                    In                                                    many applications, the high complexity of these models has to be                                                    reduced for more x efficient visualization and analysis. In our                                                    paper, we introduce an approach to derive versions at different                                                    scales from such a model through the generalization method of                                                    typification that works for curved underlying surfaces. Using the                                                    example of tiles placed on a curved roof – which occur, for                                                    example, very frequently in ancient Chinese architecture, the                                                    original set of tiles is replaced by fewer but bigger tiles while                                                    keeping a                                                    similar appearance. In the first step, the distribution of the                                                    central points of the tiles is approximated by a spline surface.                                                    This is                                                    necessary because curved roof surfaces cannot be approximated by                                                    planes at large scales. After that, the new set of tiles with less                                                    rows and/or columns is distributed along a spline surface generated                                                    from a morphing of the original surface towards a plane. The                                                    degree of morphing is dependent on the desired target scale. If the                                                    surface can be represented as a plane at the given resolution, the                                                    tiles may be converted to a bump map or a simple texture for                                                    visualization. In the final part, a perception-based method using                                                    CSF                                                    (contrast sensitivity function) is introduced to determine an                                                    appropriate LoD (level of detail) version of the model for a given                                                    viewing scenario (point of view and camera properties) at                                                    runtime.

Abstract

In recent years, the integration of semantics into 3D city models has                                                    become a consensus. The CityGML standard laid the foundation for the                                                    storage and application of semantics, which boosts the progress of                                                    semantic 3D city modeling. This paper reports an extended semantic                                                    model based on CityGML and its visual applications under the content                                                    of a three-dimensional GIS project of China. Firstly, concepts Room,                                                    Corridor and Stair are derived from concept Space which represents                                                    the similar concept of Room in CityGML. These concepts will benefit                                                    the application of indoor navigation. Geological model is also                                                    supported by this model, which enables the underground analysis.                                                    Secondly, a semi-automatic data integration tool is developed. The                                                    types of semantic concept are defined based on the Technical                                                    Specification for Three-Dimensional City Modeling of China which                                                    leads to an adaptive way to assign semantics into pure geometry. In                                                    order to better visualize the models enriched by semantics, two                                                    fundamental techniques, data reduction and selective representation                                                    are then introduced. It shows that semantics could not only help                                                    improve the performance of exploration tasks but also enhance the                                                    efficiency of spatial cognition. Finally, two exploration cases are                                                    presented, one is indoor navigation, the semantic model is used to                                                    extract the geometric path and a semantics enhanced navigation                                                    routine is used, which greatly enriches the connotation of ordinary                                                    navigation applications; the other is a unified profiler, in order                                                    to fill up the cross-section correctly, semantics are incorporated,                                                    which help ensure the topological and semantic consistency.

Abstract

Spatial data declustering is an important data processing method for                                                    parallel spatial database especially in shared nothing parallel                                                    architecture. Spatial data declustering can achieve parallel                                                    dataflow to exploit the I/O bandwidth of multiple parallel nodes by                                                    reading and writing them in parallel, which can improve the                                                    performance of parallel spatial database evidently. Aiming at the                                                    unique spatial objects locality, this paper presents a novel spatial                                                    data declustering method, which uses Hilbert space-filling curve to                                                    impose a linear ordering on multidimensional spatial objects, and to                                                    partition spatial objects logical segments according to this                                                    ordering to preserve spatial locality of spatial objects, and then                                                    to allocate logical segments to physical parallel nodes based on                                                    round-robin rule. Experimental results show that the proposed method                                                    can obtain well spatial data declustering results.

Abstract

针对时域、空间、专题、分辨率等多种语义相互关联所导致的遥感信息处理服务组合的准确性难题,提出了一种基于语义匹配的遥感信息处理服务组合方法,包括多层次的遥感信息处理服务语义匹配和渐进精化的服务组合,即时构建与用户需求相关的服务关系与或图,将后续服务选择范围限定在需求相关服务的范围之内,在关系与或图中进行启发式搜索,并选择语义匹配度最高的子图作为服务组合的结果。

Abstract

针对结构错综复杂的目标实时绘制中的遮挡剔除问题,提出了部件可视锥概念,用一个圆锥区域描述部件在考虑其邻近范围其他部件联合遮挡情况下的可视区域,并提出了基于部件可视锥的遮挡剔除算法,实现了实时绘制过程中可见性的快速判断,并以一个典型的虚拟建筑环境为例测试了本文方法的有效性。实验证明,利用可视锥能简化绘制过程中的可见性识别,大大提高实时绘制效率。

Abstract

提出了QoS感知的多任务服务优化组合非合作博弈模型,准确刻画了不同任务之间的竞争关系,在此基础上设计了顾及QoS的遥感信息服务优化组合反应函数,为求解遥感信息服务优化组合奠定理论基础。理论和实验分析表明,该模型有利于减少任务并发时的资源冲突,最大化所有任务的平均效用。

Abstract

The efficient display of flooding in intertidal zones is crucial to                                                    coastal applications (e.g., coastal zone management and anti-flood                                                    directing systems). This paper proposes a new algorithm to plot                                                    flooded intertidal areas. Initially, a digital tide-coordinated                                                    shoreline (DTS) is traced on the basis of creating a digital                                                    intertidal zone model (DIZM) and an instantaneous water surface                                                    model (IWSM). Then unconnected depressions are obtained depending on                                                    the type of DTS. At the same time, the algorithm detects unconnected                                                    depressions by considering the influences of the changing water                                                    level, and creates an index from different water levels to                                                    corresponding depressions. Finally, unconnected depressions are                                                    effectively handled and flooded areas are plotted correctly.                                                    Experimental results demonstrate that the proposed algorithm results                                                    in a more accurate and efficient display than with traditional                                                    algorithms.

Abstract

根据海洋大气环境的多维动态特征设计了应用于专业领域的可视化系统结构体系,阐述了系统开发的关键技术并实现了系统的开发,最后以一个实例介绍系统的具体应用。

Abstract

房产管理的产权对象在三维空间中的变化具有显著的多样性与异步性特征,已有的模型以二维地图方式表达建筑物整体的动态变化,很难准确有效地表达真三维建筑多重产权实体变更的不同步性。本文充分利用房产对象的空间层次关联性及产权单元的语义约束知识,定义了从地块到幢、层、户和权属的多层次事件概念,建立了三维房产从外至内动态表示的概念模型,为三维城市空间中建筑物的变迁以及房地产权属异动的准确表达与时空分析奠定了基础。

Abstract

针对复杂三维城市模型动态可视化中实时碰撞检测的可靠性和高性能需求,充分顾及离散检测与连续检测的特点,建立了视点运动空间的胶囊体模型,并定义了其描述参数,提出了基于该模型进行实时碰撞检测的两步检测算法。其中,预检测用来提高计算效率,而精检测则有力地保证了检测的准确性。利用典型的虚拟建筑环境进行实验,证明了该算法的有效性。

Abstract

针对遥感信息服务中用户需求语义的复杂性,数据维度语义的丰富性,传感器语义的多样性,遥感信息处理语义的错综复杂性和遥感信息传输语义的时变性,从用户语义约束、数据语义约束、处理服务功能语义约束和处理服务质量语义约束等4个不同层次,建立多层次语义约束模型。

Abstract

Data skew is one of most important reasons to deteriorate the                                                    performance of parallel spatial database. This paper studies the                                                    issues of handling data skew in shared nothing parallel spatial                                                    database system architecture. A novel data skew handling method is                                                    proposed, which fulfill spatial data distribution balancing based on                                                    the spatial proximity of data fragments. The minimum spatial                                                    proximity is used to be the principle of moving data fragments among                                                    different network parallel nodes. Our experimental results show that                                                    the proposed data skew handling method can achieve dynamic data load                                                    balancing and offer significant improvement for reducing response                                                    time of parallel spatial queries.

Abstract

Spatial data balancing distribution can evidently improve the                                                    performance of parallel spatial database in shared nothing parallel                                                    architecture. Considering spatial locality and unstructured variable                                                    length characteristics of spatial data, this paper proposes a                                                    dynamic spatial data balancing distribution method under shared                                                    nothing parallel database environment. By using Hilbert ordering                                                    code to keep spatial locality relationship between spatial objects,                                                    the presented method can fulfill spatial data static balancing                                                    distribution status, which depends on hierarchically decomposing                                                    Hilbert space-filling curve code to allocate approximately even                                                    spatial data volume to parallel nodes in distributed network. Then                                                    spatial proximity index is introduced to resolve spatial data                                                    unbalancing problem caused by spatial database dynamic updating.                                                    Through moving spatial data fragments to goal node which is the                                                    minimum spatial proximity with data moving out node, the spatial                                                    database redistributing strategy can attain dynamic data balance                                                    among all network parallel nodes. Our experimental results show that                                                    the proposed method can effectively improve parallel performance                                                    deterioration resulted from spatial data unbalancing and achieve                                                    spatial data dynamic balancing distribution in parallel spatial                                                    database.

Abstract

Recently many applications require an automatic processing of massive                                                    unstructured 3D point clouds in order to extract planar surfaces of                                                    man-made objects. While segmentation is the essential step in                                                    feature extracting process, but bad-segmentation results (i.e. under                                                    and over-segmentation) are still standing as a big obstacle to                                                    extract planar surfaces with best fit reality. In this paper, we                                                    propose an extension of "SEQ-NVRANSAC" approach to avoid the                                                    bad-segmentation problems using topology information and intuitive                                                    threshold value. First, in order to avoid the under-segmentation                                                    problem, we check each one group which resulted from original                                                    "SEQ-NV-RANSAC" approach to get all neighbours points which have                                                    Euclidean distance less than the threshold value as a one surface                                                    group. This process will be repeated until no more points can be                                                    adding to that surface group. Then a new surface group will be                                                    created to check the remaining points. Second, in order to solve the                                                    oversegmentation, we propose three checks; the similarity of normal                                                    vectors (NV), the perpendicular distance and the intersection zone                                                    using bounding box test.

Abstract

The way we interact with spatial data has been changed from 2D map to                                                    3D Virtual Geographic Environment (VGE). Three-dimensional                                                    representations of geographic information on a computer are known as                                                    VGE, and in particular 3D city models provide an efficient way to                                                    integrate massive, heterogenous geospatial information and                                                    georeferenced information in urban areas. 3D city modeling (3DCM) is                                                    an active research and practice topic in distinct application areas.                                                    This paper introduces different modeling paradigms employed in 3D                                                    GIS, virtual environment, and AEC/FM. Up-to-date 3DCM technologies                                                    are evolving into a data integration and collaborative approach to                                                    represent the full spatial coverage of a city, to model both                                                    aboveground and underground, outdoor and indoor environments                                                    including man-made objects and natural features with 3D geometry,                                                    appearance, topology and semantics.

Abstract

Because of detailed geometrical components based description, 3D                                                    complex building contains the most elaborated perceptual and                                                    comprehensive semantic information. However, since the lack of                                                    optimal simplification method, the automatic LOD generation of                                                    such kind of model becomes a bottle neck which prohibited the                                                    high-fidelity 3D city applications. This paper proposed a                                                    perceptually guided geometrical primitive location method for the                                                    optimal simplification of 3D complex buildings. Firstly, the                                                    rendered image is snapped and a 2D discrete wavelet transform based                                                    human vision system filtering approach is adopted to extract                                                    the imperceptible details in the image, and then a kind of visual                                                    difference image is generated with sufficient perceptual                                                    information.                                                    Secondly, a ray-casting like method is proposed to precisely map the                                                    perceptual information from the image onto the geometric                                                    primitives. The statistics is carried out to determine whether a                                                    traced primitive is to be preserved or simplified. The results show                                                    that                                                    this method is able to efficiently locate the perceptible primitives                                                    and leave the imperceptible and undisplayable primitives to be                                                    further handled by simplification operations which enable a strong                                                    perceptual feature preserved simplification of 3D complex                                                    building models.

Abstract

One issue of GIS is management of huge amount of spatial data.                                                    Nowadays, acquisition capacity of 3D spatial data with various                                                    scales and resolutions is much more convenient due to new 3D                                                    acquisition technologies. It is a difficulty that how to efficiently                                                    and synthetically organize and manage large scale underground 3D                                                    spatial data with contents of continuous distribution and                                                    nonuniformity. A 3D GIS data management system framework with three                                                    layers is proposed to deal with large scale underground data                                                    integrated management. The related key issues and methods include:                                                    (1) Multi-scale underground spatial object concept model. (2) 3D                                                    spatial database model considering spatial and semantic relationship                                                    and corresponding data structure is introduced to support extendable                                                    storage environment such as file system, typical commercial database                                                    management system and cluster parallel system. (3) True 3D spatial                                                    index considering level of detail (LOD). (4) Efficient dynamic                                                    dispatch method of great amount of 3D spatial data is adopted based                                                    on 3D data content and associated information. (5) 3D spatial data                                                    engine (SDE) provides a uniform access interface for file management                                                    system, relational database management system and cluster parallel                                                    system and other applications. The 3D GIS database model focuses on                                                    the key issues of massive underground 3D spatial data provides a new                                                    way for the high performance database organization and management of                                                    true 3D geological data as well as its integration with the                                                    aboveground spatial data.

Abstract

The evaluation of urban landscape and the design of urban space are                                                    in need of a scientific visual analysis tool that can wholly include                                                    the qualitative analysis, the quantitative analysis and the                                                    orientation analysis. With the outstanding saving, management,                                                    visualization and analytical functions of 3D space information,                                                    3DGIS can exactly provide powerful technique support for this. Based                                                    on the humanistic analysis conception, the concept of visual                                                    openness index is introduced, and some visual analysis functions are                                                    designed and implemented based on VGEGIS platform. Finally a case                                                    study for the application of visual analysis is carried out and the                                                    results show that the urban design scheme evaluation is improved                                                    distinctively.

Abstract

Depth contours on a chart are important for safe navigation. The                                                    ambiguity problem can appear when points of equal depth are joined                                                    in contouring. Unreasonable solutions may mistake a shallow area for                                                    a deep one, which could result in a potential danger for navigation.                                                    A solution is presented to solve the ambiguity problem using                                                    constrained lines formed by two shallow depths. The constrained                                                    lines are used to limit the joining of the points with equal depth.                                                    Experimental results demonstrate that the proposed solution can                                                    reduce the dangers of producing non-existent deep areas in                                                    bathymetric contouring.

From 2D to 3D road networks

Abstract

The existing road‐network models based on the 2D link‐node of roadway                                                    centrelines have inhibited lane‐oriented network flow analysis and                                                    multi‐dimensional inventory management in complicated 3D urban                                                    environments. This paper proposes a hierarchical lane‐oriented 3D                                                    road‐network model (HL‐3DRNM), with a unified modelling language                                                    (UML) diagram. HL‐3DRNM is a non‐planar topological model with the                                                    support of a 3D lane ribbon cartographic display, which is                                                    characterized by: (1) multiple topological and cartographic                                                    representations and various abstraction levels (street, road                                                    segment, carriageway and lane); and (2) referenced multi‐dimensional                                                    road information (point, line, area and volume) at lane level.                                                    HL‐3DRNM provides solid mathematical foundations for a more detailed                                                    inventory management, effective network analysis and realistic                                                    navigation in the increasingly complicated 3D urban transportation                                                    systems.

Abstract

A three-dimensional (3D) spatial index is required for real time                                                    applications of integrated organization and management in virtual                                                    geographic environments of above ground, underground, indoor and                                                    outdoor objects. Being one of the most promising methods, the R-tree                                                    spatial index has been paid increasing attention in 3D geospatial                                                    database management. Since the existing R-tree methods are usually                                                    limited by their weakness of low efficiency, due to the critical                                                    overlap of sibling nodes and the uneven size of nodes, this paper                                                    introduces the k-means clustering method and employs the 3D overlap                                                    volume, 3D coverage volume and the minimum bounding box shape value                                                    of nodes as the integrative grouping criteria. A new spatial cluster                                                    grouping algorithm and R-tree insertion algorithm is then proposed.                                                    Experimental analysis on comparative performance of spatial indexing                                                    shows that by the new method the overlap of R-tree sibling nodes is                                                    minimized drastically and a balance in the volumes of the nodes is                                                    maintained.

Comparison of extraction on a plain region.                                                        (a) Extraction result of proposed method. (b) Extraction result                                                        of method implemented                                                        in ArcGIS.

Abstract

Depression filling and direction assignment over flat areas are                                                    critical issues in hydrologic analysis. This paper proposes an                                                    efficient approach for the treatment of depressions and flat areas,                                                    based on gridded digital elevation models. Being different from the                                                    traditional raster neighborhood process which is time consuming, a                                                    hybrid method of vector and raster manipulation is designed for                                                    depression filling, followed by a neighbor-grouping scan method to                                                    assign the flow direction over flat areas. The results from                                                    intensive experiments show that there is a linear relationship                                                    between time efficiency and data volume, and the extracted                                                    hydrologic structures of flat areas are also more reasonable than                                                    those proposed by the existing methods.

Abstract

This paper describes a series of tests that measured the effects of                                                    4 factors (accuracy, density of source data, characteristics of the                                                    terrain surface, and modeling approaches) on the accuracy of digital                                                    elevation models (DEMs). A large area covered by 2 1:10,000-scale                                                    maps was selected for testing. The terrain types ranged from flat to                                                    hilly to mountainous. Results and conclusions are provided.