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In recent years, it has been widely agreed that spatial features derived from textural, structural, and object-based methods are important information sources to complement spectral properties for accurate urban classification of high-resolution imagery. However, the spatial features always refer to a series of parameters, such as scales, directions, and statistical measures, leading to high-dimensional feature space. The high-dimensional space is almost impractical to deal with considering the huge storage and computational cost while processing high-resolution images. To this aim, we propose a novel multi-index learning (MIL) method, where a set of low-dimensional information indices is used to represent the complex geospatial scenes in high-resolution images. Specifically, two categories of indices are proposed in the study: (1) Primitive indices (PI): High-resolution urban scenes are represented using a group of primitives (e.g., building/shadow/vegetation) that are calculated automatically and rapidly; (2) Variation indices (VI): A couple of spectral and spatial variation indices are proposed based on the 3D wavelet transformation in order to describe the local variation in the joint spectral-spatial domains. In this way, urban landscapes can be decomposed into a set of low-dimensional and semantic indices replacing the high-dimensional but low-level features (e.g., textures). The information indices are then learned via the multi-kernel support vector machines. The proposed MIL method is evaluated using various high-resolution images including GeoEye-1, QuickBird, WorldView-2, and ZY-3, as well as an elaborate comparison to the state-of-the-art image classification algorithms such as object-based analysis, and spectral-spatial approaches based on textural and morphological features. It is revealed that the MIL method is able to achieve promising results with a low-dimensional feature space, and, provide a practical strategy for processing large-scale high-resolution images. 相似文献
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ABSTRACTVirtual globes are technologies for visual navigation through a three-dimensional, multi-resolution model of the entire planet. Data representations used in virtual globes, however, lack geometric flexibility at high-resolution levels of the planet-wide terrain surface. This is a problem especially if boundaries between individual geospatial features and the terrain are important. A novel integration of individual polygonal boundaries with a specific multi-resolution representation of the planet-wide terrain is developed in this article. In the preparation stage, the integration relies on an original simplification algorithm applied to the polygonal boundaries between geospatial features and the terrain. Its output is a multiple level-of-detail (LOD) geometry, which can be combined with a known multi-LOD representation of the terrain that uses run-time triangulation. This data representation is suitable for storage in existing database systems, avoids any data redundancy across LODs, and is even independent of the subdivision schema that partitions the planet's surface for the sake of dealing with LODs. At run-time, a novel reconstruction algorithm stitches geometric parts from different LODs together in a manner that augments the multi-LOD representation of the terrain. Within a certain proximity range from a given position, the method reconstructs a scene that preserves topological relations between the boundaries of geospatial features with the terrain. The method also guarantees that certain nearest proximity to the given position consists of the best geometries that correspond to the original datasets. Such properties of the method close up the gap between a mere exploratory visualization of static, pre-generated models and the models supporting geospatial analysis, which is deemed crucial for applications in Geographic Information Systems, Building Information Modelling and other software industries. A prototype implementation and experiment results that prove this method are also presented. 相似文献
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随着地铁的不断建设与投入使用,我国正在逐步进入地铁运营养护期,地铁病害检测与运营养护也逐渐得到重视。随着地铁运营年限的增加,病害也呈现加重趋势。通过三维激光扫描技术获取隧道病害全面信息,利用空间自相关性分析地铁隧道病害的地理空间分布特征,对于认识病害形成机理,防治病害具有重要意义。本文以某地铁隧道通过三维激光扫描所获得的水平收敛数据为基础,利用空间自相关分析法定量分析了病害在地理空间上的分布特征,以及与周边水文地质环境的关系。结果表明,隧道病害在地理空间分布上呈现显著的空间正相关与空间集聚特性,且病害严重区与隧道周边水文地质环境密切相关。本文结果为隧道病害地理空间分布特征研究、认识病害分布规律及后期病害治理提供了有效依据。 相似文献
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多细节层次的三维城市模型是数字城市和智慧社会的关键空间数据基础设施,从基于稀疏点线特征的交互式半自动化建模到基于密集点云的自动化智能化建模已经成为国际学术界和工业界的热点前沿。由于立体城市空间结构的复杂性,多类型、多站点和多时相的点云数据融合处理是三维城市建模的基本途径,其基本思想是将具有不同视角、密度、精度、尺度、细节、时间历元等特征的多点云数据进行一致性融合表达与集成处理,建立可直接面向计算分析的智能化表达的多点云模型。归纳总结了多点云数据的主要特点,针对时空基准与精度、尺度、语义3个层面的一致性处理,分析了多点云数据融合的主要发展趋势,并凝练了面向三维城市建模的多点云数据融合关键问题。 相似文献
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地勘工程3维空间数据模型及其数据结构设计 总被引：44，自引：1，他引：44
3维现象随着研究领域的不同，描述空间实体的方法存在较大差异，不可能设计一种数据模型来适合所有的应用领域，应根据研究领域空间实体分布特征，设计出专用的3维空间数据模型。本文对传统的3维数据模型进行了分析，以地质勘探工程的各种3维空间对象为研究背景，提出了适合地质勘探工程的矢量与栅格集成的面向对象混合数据模型，以复杂体－体－面－线－点对象之间的逻辑关系来建立对象之间的拓扑关系，设计了部分对象的数据结构，并以一玢岩型铁矿床为例，对数据结构进行了描述。 相似文献
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针对雷达探测范围会受到复杂地形因素影响,单一地依靠电磁传播模型可视化雷达探测区域很难真实有效地展现电磁覆盖情况的问题,该文提出一种基于GeoSOT-3D空间剖分的雷达探测范围的计算与表达一体化的真三维模型。GeoSOT-3D剖分框架将上至地球50 000km,下至地心的全部地球空间划分成多层次、多尺度空间体元,体元可承载多源异构空间数据。依据GeoSOT-3D的剖分流程,将地形数据、雷达探测空间数据离散化。最后,开发了雷达探测范围可视化验证平台。实验结果表明,该建模方法对复杂的地形适应性强,可视化表现效果真实直观。 相似文献
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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. 相似文献
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当前云计算的发展已能支持高性能的地理空间服务,比如在数字城市和电子商务等行业。Apache基金支持下的开源软件框架Hadoop,可以用来构建一个云环境的集群用来存储和处理高性能的地理空间数据。开放地理空间联盟(OGC)的Web三维服务(W3DS)就是这样一个很好的三维的地理空间数据服务标准。在标准的云计算环境下将是一个更好的应用示范。基于此,本文研究了OGC的W3DS服务在云计算环境下的实验结果。实验采用Apache的Hadoop框架作为三维地理空间信息服务实验展示的基础。实验结果对展示高性能的三维地理空间信息提供了有价值的参考。 相似文献
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The world’s rising urban density expansion has resulted in a proliferation of attempts to efficiently use space and a higher level of spatial complexity in metropolitan areas. 3D geospatial data models are increasingly being embraced to facilitate communicating the spatial dimensions of complex built environments in different applications. For example, the use of 3D models in land administration systems has been recognized as a good approach for communicating the spatial complexity of legal spaces within multi‐storey buildings. The spatial extent of legal space—to which rights, restrictions and responsibilities relate in a 3D digital cadastre—needs to be accurately defined and geometrically closed; watertight. Therefore, this study aims to address the challenges regarding checking the closure of diverse 3D legal spaces and engage several techniques to formulate the watertight concept for cadastre. The research’s methodology is built on a 3D polyhedral surface using a half‐edge data structure. A primitive check is employed to assess the spatial consistency of lower‐dimensional primitives of 3D objects. Subsequently, advanced closure checks ensure the closure of volumetric legal spaces represented by 2‐manifold and non‐2‐manifold data models. The article concludes that, by adopting the proposed approaches, the internal spatial consistency of legal spaces in urban land administration will be certified. 相似文献
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针对现有建筑物多细节层次（level of detail,LOD）表达主要面向外部,很少涉及内部空间的问题,提出一种含室内空间结构的建筑物三维LOD概念模型。该模型分为LOD0~LOD6 7个LOD,细节层次由建筑物的基底平面图、幢模型、无侧面楼层模型、楼层模型、户模型、房间模型到含门、窗等建筑语义的信息房间模型,空间细节逐次变细,丰富了建筑物室内空间LOD的表达理论。为构建这种LOD模型,提出基于胞腔复形链边界算子和上边界算子的LOD生成方法。该方法引入代数拓扑的胞腔、胞腔复形和复形链3个概念,利用胞腔和胞腔复形表达LOD,并在LOD6的基础上,利用边界算子和上边界算子生成其他粗空间粒度LOD模型,为三维城市模型建筑物LOD构建提供一种新方法。 相似文献
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《ISPRS Journal of Photogrammetry and Remote Sensing》2000,55(3):139-149
When we map an area or create a digital database for it, the first task is often to partition the space into smaller units. There are traditionally two methods of partitioning: vector and raster. A vector partition delineates the boundary of features by polylines while a raster partition subdivides the space into a regular matrix of square or rectangular pixels. These two are complementary methods of subdividing the space either by features or by unconstrained space cells. In the third dimension, they are extended to polyhedra and voxels, respectively. We will argue in this paper that the terms “vector” and “raster” cannot describe all cases of tessellation. With advances in data modelling, variations of the two traditional methods have been developed, such as the representation of a feature by pixels and not by polylines. At present, there is a lack of systematic terminology to describe the various methods of tessellation. In this paper, we will propose a taxonomy for three-dimensional space tessellation. Its essential feature is to distinguish between abstract concepts of tessellation and their encoding methods. We recognise that tessellation of geographic space is carried out in different stages with increasingly precise mathematical meaning. This provides us with an insight into the process of spatial tessellation and a model to systematically describe the various structures. These concepts could form a basis for spatial data models. 相似文献
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为了能快速计算室内导航路径,必须使用简单的数据结构表达室内复杂的路径导航信息,室内三维连通图就是一种较好的手段。但是传统的室内精细建模重在几何模型的构建和纹理数据采集,缺乏室内三维连通图的构建。针对广泛存在室内几何模型提出一种基于体素的室内三维连通图自动生成算法,对建筑物内部进行分割和填充,将室内空间划分为离散的导航空间,通过自动语义关联提取连通关系,最终生成室内空间三维连通图。 相似文献
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将等高线看作是由高程点以特定形式组织得到的空间三维线段,采用3维Douglas-Peucker算法从三维空间提取等高线上的主要特征点。根据等高线数据特点,对该算法进行等高线综合的几种方案进行实验讨论。实验结果和运算速度表明,采用3维Douglas-Peucker算法综合等高线具有广阔的研究前景。 相似文献
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Dynamic geospatial complex systems are inherently four‐dimensional (4D) processes and there is a need for spatio‐temporal models that are capable of realistic representation for improved understanding and analysis. Such systems include changes of geological structures, dune formation, landslides, pollutant propagation, forest fires, and urban densification. However, these phenomena are frequently analyzed and represented with modeling approaches that consider only two spatial dimensions and time. Consequently, the main objectives of this study are to design and develop a modeling framework for 4D agent‐based modeling, and to implement the approach to the 4D case study for forest‐fire smoke propagation. The study area is central and southern British Columbia and the western parts of Alberta, Canada for forest fires that occurred in the summer season of 2017. The simulation results produced realistic spatial patterns of the smoke propagation dynamics. 相似文献
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The representation of similarity transformation in three-dimensional (3D) space, especially of orientation, is a crucial issue in navigation, geodesy, photogrammetry, robot arm manipulation, etc. Considering the large amount of computer resources required by iterative algorithms designed for spatial similarity transformation, the high dependence on initial values of unknown parameters, and the instability of solving transformation parameters for large-angle registration, a closed-form solution for pairwise light detection and ranging (LiDAR) point cloud registration is proposed. In this solution, dual-number quaternions are used to represent the 3D rotation. The relationship between the rotation matrix-based representation of similarity transformation and the dual quaternion-based representation is described first. Considering that the same features from two neighboring stations coincide after pairwise registration, a dual quaternion-based error norm, which is associated with the sum of the position errors, is constructed. Based on theory of least squares and by extreme value analysis of the error norm, detailed derivations of the model and the main formulas are obtained. Once the similarities between the same features from the two neighboring LiDAR stations are constructed, the rotation matrix, the scale parameter, and the translation vector are simultaneously derived. Two experiments are conducted to verify the feasibility and effectiveness of the proposed algorithm. The proposed algorithm has the advantages of simplicity and ease of implementation, making it better than the traditional methods that use matrices to describe spatial rotation. Moreover, it solves the transformation parameters without the initial estimates of unknown parameters, making it better than iterative algorithms. Most importantly, in contrast to unit quaternion-based algorithms, the proposed algorithm solves seven unknown parameters simultaneously. Therefore, it effectively avoids the accumulation of introduced error in calculation and the negative impact from the inappropriate choice of initial values. 相似文献
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