共查询到20条相似文献,搜索用时 93 毫秒
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在海量空间数据的组织与表达方面,与传统的空间数据模型与方法相比,地球剖分网格表现出了极大的优势。鉴此,本文提出了一种剖分网格下顾及用户兴趣的矢量地图多尺度表达方法,首先利用大量POI数据构建空间兴趣场模型,描述用户对地理信息的兴趣的空间分布;然后对空间要素进行分类分级,确定其表达的尺度范围;运用GeoSOT剖分理论划分不同层次的剖分面片,建立剖分面片与尺度的对应关系,根据用户对剖分面片所在区域的兴趣度大小,表达不同详细程度的空间要素,实现基于用户兴趣的空间数据多尺度表达。实验表明,该方法能够满足用户由概略到详细、由重要到次要的空间认知需求,同时能够获得较好的多尺度表达效果。 相似文献
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基于HBase的空间矢量数据存储模型设计与优化 总被引:1,自引:0,他引:1
数据存储模型是数据库模型的重要组成部分。本文针对目前关系型空间数据库发展过程中遇到的瓶颈问题以及采用HBase管理空间矢量数据存在的问题,在分析关系型空间数据库存储模型的基础上,将关系型数据库存储模式向HBase存储模式转换规则应用到空间矢量数据管理领域,提出了空间矢量数据关系存储模式向HBase存储模式转换方法,设计了一种空间矢量数据HBase存储模型。利用HBase的实体嵌套、反范式化、无模式等特性,对模型进行了优化完善。通过试验验证了在没有辅助索引情况下,本文设计的存储模型查询效率优于目前常用的基于HBase的空间矢量数据存储模型。 相似文献
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基于球面离散格网的遥感数据剖分编目模型研究 总被引:1,自引:1,他引:0
针对目前各个遥感数据的编目多样,缺乏全球统一的遥感数据编目体系的现状,本文基于球面剖分模型,参考并借鉴成熟的文献信息编目的相关理论,系统构建了全新的全球遥感数据剖分编目模型,以期更有效地组织、存储和管理大范围多尺度的遥感数据。首先,介绍了文献数据的编目理论和球面剖分格网的基本框架,然后探讨了基于全球剖分格网的遥感数据面片编目方法,其中包括描述著录方法和标引著录方法,最后设计了遥感剖分编目数据的管理框架和编目服务器的组织方法。研究表明,基于球面离散格网的遥感数据剖分编目模型为实现遥感数据的全球化、层次化和规范化管理提供了坚实的理论基础。 相似文献
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网络环境下海量、高维、动态、多尺度地理空间矢量场数据的在线高效可视化,一直是大规模密集矢量场数据集成与综合应用分析亟须解决的关键问题。地理矢量场数据蕴含大量非规则、多尺度、时空异质的变化特征与结构,传统矢量场纹理可视化方法,受全局统一采样密度的限制,存在典型的稠密遮挡、特征模糊的问题。针对上述问题,本文提出了一种顾及地理矢量场空间变化特征的多分辨率纹理可视化方法,引入复合信息熵定量显式描述矢量场的空间变化,以此驱动图像空间内多频噪声纹理生成、矢量场多分辨率纹理的构建与增强表达,有效克服传统纹理可视化方法的技术瓶颈。最后采用风场数据进行试验,验证了本文方法的可靠性与有效性。 相似文献
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在利用遥感影像更新GIS矢量数据的过程中,往往忽略了对已知信息的有效利用,针对这一问题,本文提出一种基于点分布的双蛇模型用于GIS矢量数据更新,该模型利用已有遥感影像信息计算目标边界点的平均分布,以此为"镜面"建立初始矢量边界的"镜像",将两边界各自演化的结果取平均作为更新后的GIS矢量边界。该方法同时利用了GIS和遥感的历史数据作为先验知识,分别作为蛇模型的初始位置和区域约束信息,使遥感与GIS信息结合更加紧密。仿真实验表明,基于点分布的双蛇模型在GIS矢量边界更新的应用中,可以得到比以传统蛇模型更好的更新准确率和多边形相似度,并且接近手工方法的效果。 相似文献
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An efficient data organization and scheduling strategy for accelerating large vector data rendering
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Rendering large volumes of vector data is computationally intensive and therefore time consuming, leading to lower efficiency and poorer interactive experience. Graphics processing units (GPUs) are powerful tools in data parallel processing but lie idle most of the time. In this study, we propose an approach to improve the performance of vector data rendering by using the parallel computing capability of many‐core GPUs. Vertex transformation, largely a mathematical calculation that does not require communication with the host storage device, is a time‐consuming procedure because all coordinates of each vector feature need to be transformed to screen vertices. Use of a GPU enables optimization of a general‐purpose mathematical calculation, enabling the procedure to be executed in parallel on a many‐core GPU and optimized effectively. This study mainly focuses on: (1) an organization and storage strategy for vector data based on equal pitch alignment, which can adapt to the GPU's calculating characteristics; (2) a paging‐coalescing transfer and memory access strategy for vector data between the CPU and the GPU; and (3) a balancing allocation strategy to take full advantage of all processing cores of the GPU. Experimental results demonstrate that the approach proposed can significantly improve the efficiency of vector data rendering. 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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基于等概率密度误差模型建模原理和数值算法,研究矢量GIS平面一般曲线误差模型定位精度,给出定位精度捕述指标,并通过实例计算与分析,得出使川误差模型平均带宽比使用误差模型面积更能反应一般曲线的真实精度的结论,便于指导生产与应用。 相似文献
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从概率论的角度看,矢量GIS平面线状实体落入其相应误差模型内的概率值是决定线状实体误差模型规模的依据。根据等概率密度误差模型建模机理、概率论与数理统计以及数值分析,文献[1]、[3]、[4]研究了矢量GIS平面线状实体落入其相应等概率密度误差模型内的概率算法,在此基础上,文中对概率特征进行了总结和分析,得出了"线状实体落入其相应等概率密度误差模型内的概率不仅与线状实体上点位精度最低的特征点"标准误差椭圆缩放系数"有关,而且还随特征点精度的变化而变化"的结论。实例计算与分析验证了该结论的正确性。 相似文献
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Geo-Spatial Data Transfer Standard is an important part of “National Spatial Data Infrastructure (NSDI)”, as well as a necessary means for data sharing. “Chinese National Geo-Spatial Data Transfer Format (CNSDTF)” was approved by National Quality Technology Supervise Bureau in 1999 with the standard serial number of 17798-1999. It is designed to support vector and raster spatial data. This paper describes the vector part of CNSDTF, including design ideas, main characters, conceptual model, definition of spatial object, and file structure. 相似文献
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随着三维激光点云数据获取能力的提升,基于三维激光点云进行建筑物模型重建与立面测绘成为工程应用中常用的方法。三维激光点云数据能够体现建筑物丰富和直观的细节信息,然而海量数据处理给建筑物模型构建带来了极大挑战。本文通过对建筑物的三维激光点云数据进行横切得到建筑物轮廓点,并采用基于遗传算法的TSP算法对轮廓点进行处理以获取建筑物各立面的方程系数,最终实现建筑物模型的构建和获取详细的建筑物立面数据。试验结果表明,此方法可以较好地实现LOD1级建筑物模型的构建,进而为更高(LOD3)级别的建筑物模型构建提供依据。 相似文献
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多源地理空间矢量数据之间存在着隐含的关联关系,这些关联关系往往隐式存在,难以直观展示,也难以与空间数据映射交互展示,更无法进行查询分析,获取所需信息。针对这种情况,本文以多源地理空间矢量数据及统计数据为研究对象,首先定义了多源地理空间矢量数据关联的概念及分类,然后以此为基础设计了多源地理空间矢量数据关联模型,并将其分为3个子模型:基于自适应四叉树编码的空间关联子模型、基于几何匹配的空间关联子模型及基于语义匹配的空间关联子模型。该模型定义了多源地理空间矢量数据之间的关联方式,为关联关系的构建奠定了理论基础。 相似文献
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《International Journal of Digital Earth》2013,6(2):91-105
The effect of Digital Earth on our life is vital. Developing and updating Geospatial data in Digital Earth is also essential. This paper presents the application of a new approach of image registration in Digital Earth. The approach was developed based on registering a mono photograph on a master 3D model. The result is a 3D vector model, which can be broadly applied in visualisation, mapping, geographic information system (GIS), planning, change detection, as well as Digital Earth. The approach does not require parameters of correction for transformation. The accuracy of the output depends on the accuracy of the master data. This approach is very versatile and able to register any image on the digital elevation model, digital surface model and topographic 3D model. 相似文献
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The kernel function is a key factor to determine the performance of a support vector machine (SVM) classifier. Choosing and constructing appropriate kernel function models has been a hot topic in SVM studies. But so far, its implementation can only rely on the experience and the specific sample characteristics without a unified pattern. Thus, this article explored the related theories and research findings of kernel functions, analyzed the classification characteristics of EO-1 Hyperion hyperspectral imagery, and combined a polynomial kernel function with a radial basis kernel function to form a new kernel function model (PRBF). Then, a hyperspectral remote sensing imagery classifier was constructed based on the PRBF model, and a genetic algorithm (GA) was used to optimize the SVM parameters. On the basis of theoretical analysis, this article completed object classification experiments on the Hyperion hyperspectral imagery of experimental areas and verified the high classification accuracy of the model. The experimental results show that the effect of hyperspectral image classification based on this PRBF model is apparently better than the model established by a single global or local kernel function and thus can greatly improve the accuracy of object identification and classification. The highest overall classification accuracy and kappa coefficient reached 93.246% and 0.907, respectively, in all experiments. 相似文献
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基于簇模型的矢量地图数据的高效压缩方法(英文) 总被引:3,自引:2,他引:1
This paper proposes a new method for the compression of vector data map. Three key steps are encompassed in the proposed method,
namely, the simplification of vector data map via the elimination of vertices, the compression of removed vertices based on
a clustering model, and the decoding of the compressed vector data map. The proposed compression method was implemented and
applied to compress vector data map to investigate its performance in terms of the compression ratio and distortions of geometric
shapes. The results show that the proposed method provides a feasible and efficient solution for the compression of vector
data map and is able to achieve a promising ratio of compression and maintain the main shape characteristics of the spatial
objects within the compressed vector data map.
Supported by the National 863 Program of China (No. 2007AAl2Z241), the Program for New Century Excellent Talents in University
(No. NCET-07-0643), the National Natural Science Foundation of China (No. 40571134, No. 40871185), the National 973 Program
of China (No. 108085). 相似文献